Production & Supply Chain
Process Reconfiguration and Intensification: An Emerging Opportunity Enabling Efficient Carbon Capture and Low-cost Blue Hydrogen Production
Mar 2023
Publication
Low-carbon hydrogen can play a significant role in decarbonizing the world. Hydrogen is currently mainly produced from fossil sources requiring additional CO2 capture to decarbonize which energy intense and costly. In a recent Green Energy & Environment paper Cheng and Di et al. proposed a novel integration process referred to as SECLRHC to generate high-purity H2 by in-situ separation of H2 and CO without using any additional separation unit. Theoretically the proposed process can essentially achieve the separation of C and H in gaseous fuel via a reconfigured reaction process and thus attaining high-purity hydrogen of ∼99% as well as good carbon and hydrogen utilization rates and economic feasibility. It displays an optimistic prospect that industrial decarbonization is not necessarily expensive as long as a suitable CCS measure can be integrated into the industrial manufacturing process.
Design and Performance Assessment of a Solar-to-hydrogen System Thermally Assisted by Recovered Heat from a Molten Carbonate Fuel Cell
Mar 2022
Publication
Solar-to-hydrogen plants are predominantly based on steam electrolysis. Steam electrolysis requires water electricity and heat. The excess electric energy is generally converted into hydrogen via an electrolyser. The use of waste heat in hydrogen generation process promises energy efficiency improvement and production fluctuation reductions. This work investigates the techno-economic performance of the proposed system which recovers the waste heat from molten carbonate fuel cell and uses solar energy to produce steam. Comparison of thermally assisted solar system with corresponding solar system is done. The fuel cell provides 80% of the required thermal energy. The solar PV array provides the required electricity. The thermally assisted solar-to-hydrogen system annual energy efficiency (38.5 %) is higher than that of solar- to- hydrogen system. The investment cost of the proposed system is 2.4 % higher than that using only solar parabolic trough collector for the same required amount of heat. The advantage is that the fuel cell simultaneously produces electricity and heat. The recovery of waste heat allows getting an annual overall efficiency of 63.2 % for the molten carbonate fuel cell. It yields 2152 MWh of electricity per year. The 1 MW electrolysers annually generates 74 tonnes of hydrogen.
Techno-economic Assessment of Green Ammonia Production with Different Wind and Solar Potentials
Nov 2022
Publication
This paper focuses on developing a fast-solving open-source model for dynamic power-to-X plant techno-economic analysis and analysing the method bias that occurs when using other state-of-the-art power-to-X cost calculation methods. The model is a least-cost optimisation of investments and operation-costs taking as input techno-economic data varying power profiles and hourly grid prices. The fuel analysed is ammonia synthesised from electrolytic hydrogen produced with electricity from photovoltaics wind turbines or the grid. Various weather profiles and electrolyser technologies are compared. The calculated costs are compared with those derived using methods and assumptions prevailing in most literature. Optimisation results show that a semi-islanded set-up is the cheapest option and can reduce the costs up to 23% compared to off-grid systems but leads to e-fuels GHG emissions similar to fossil fuels with today’s electricity blend. For off-grid systems estimating costs using solar or wind levelized cost of electricity and capacity factors to derive operating hours leads to costs overestimation up to 30%. The cheapest off-grid configuration reaches production costs of 842 e/t3 . For comparison the "grey" ammonia price was 250 e/t3 in January 2021 and 1500 e/t3 in April 2022 (Western Europe). The optimal power mix is found to always include photovoltaic with 1-axis tracking and sometimes different types of onshore wind turbines at the same site. For systems fully grid connected approximating a highly fluctuating electricity price by a yearly average and assuming a constant operation leads to a small cost.
Anion Exchange Membrane Water Electrolysis from Catalyst Design to the Membrane Electrode Assembly
Jul 2022
Publication
Anion exchange membrane (AEM) electrolysis aims to combine the benefits of alkaline electrolysis such as stability of the cheap catalyst and advantages of proton-exchange membrane systems like the ability to operate at differential pressure fast dynamic response low energy losses and higher current density. However as of today AEM electrolysis is limited by AEMs exhibiting insufficient ionic conductivity as well as lower catalyst activity and stability. Herein recent developments and outlook of AEM electrolysis such as cost-efficient transition metal catalysts for hydrogen evolution reaction and oxygen evolution reaction AEMs ionomer electrolytes ionomer catalyst–electrolyte interaction and membrane-electrode assembly performance and stability are described.
Techno-economic Analysis of On-site Blue Hydrogen Production Based on Vacuum Pressure Adsorption: Practical Application to Real-world Hydrogen Refueling Stations
Feb 2023
Publication
Although climate change can be efficiently curbed by shifting to low-carbon (blue) hydrogen as an energy carrier to achieve carbon neutrality current hydrogen production mainly proceeds via the gray pathway i.e. generates large amounts of CO2 as a byproduct. To address the need for cleaner hydrogen production we herein propose novel CO2 capture processes based on the integration of vacuum pressure swing adsorption into a gray hydrogen production process and perform retrofitting to a blue hydrogen production process for on-site hydrogen refueling stations. Techno-economic analysis reveals that the implementation of the proposed capture processes allows one to significantly reduce CO2 emission while preserving thermal efficiency and the economic feasibility of this implementation in different scenarios is determined by computing the levelized cost of hydrogen. As a result blue hydrogen is shown to hold great promise for the realization of sustainable energy usage and the net-zero transition.
Thermodynamic Assessment of a Hybrid Methane Cracking System for Liquified Hydrogen Production and Enhanced Oil Recovery Using CO2
Oct 2022
Publication
Hydrogen fuel production from methane cracking is a cleaner process compared to steam methane reforming due to zero greenhouse gas emissions. Carbon black that is co-produced is valuable and can be marketed to other industries. As this is a high-temperature process using solar energy can further improve its sustainability. In this study an integrated solar methane cracking system is proposed and the efficient utilization of the hydrogen and carbon products is explored. The carbon by-product is used in a direct carbon fuel cell and oxy- combustion. These processes eliminate the need for carbon capture technologies as they produce pure CO2 exhaust streams. The CO2 produced from the systems is used for enhanced oil recovery to produce crude oil. The produced turquoise hydrogen is liquified to make it suitable for exportation. The process is simulated on Aspen Plus® and its energy and exergy efficiencies are evaluated by carrying out a detailed thermodynamic analysis. A reservoir simulation is used to study the amount of oil that can be produced using the captured CO2. The overall system is studied for oil production over 20 years and energy and exergy of efficiencies 42.18% and 40.18% respectively were found. Enhanced oil recovery improves the recovery rate from 24.8% to 64.3%.
Demonstration of Green Hydrogen Production Using Solar Energy at 28% Efficiency and Evaluation of its Economic Viability
Jan 2021
Publication
The solar to hydrogen (STH) efficiency of photovoltaic-electrolysis (PV-E) setups is a key parameter to lower the cost of green hydrogen produced. Commercial c-Si solar cells have neared saturation with respect to their efficiency which warrants the need to look at alternative technologies. In this work we report a concentrator photovoltaic-electrolysis (CPV-E) setup with a STH efficiency of 28% at 41 suns (without the use of Fresnel lenses) the highest reported efficiency using an alkaline system to date. Using this as a base case we carried out a detailed techno-economic (TEA) analysis which showed that despite the high cost associated with CPV cells the levelized cost of hydrogen (LCOH) is at $5.9 kg1 close to that from c-Si solar farms ($4.9 kg1 ) primarily due to the high STH efficiency. We also report sensitivity analysis of factors affecting both CPV and alkaline electrolyser systems such as the CPV module efficiency and installed capacity electrolyser stack lifetime operating current density and working hours. Our results indicate that in a scenario where the installed capacity of CPV technology matches that of silicon and with an electrolyser operating current density of 0.7 A cm2 the LCOH from CPV electrolysis systems can be.
Techno-economic Assessment of a Chemical Looping Splitting System for H2 and CO Co-generation
Feb 2022
Publication
The natural gas (NG) reforming is currently one of the low-cost methods for hydrogen production. However the mixture of H2 and CO2 in the produced gas inevitably includes CO2 and necessitates the costly CO2 separation. In this work a novel double chemical looping involving both combustion (CLC) and sorption-enhanced reforming (SE-CLR) was proposed towards the co-production of H2 and CO (CLC-SECLRHC) in two separated streams. CLC provides reactant CO2 and energy to feed SECLRHC which generates hydrogen in a higher purity as well as the calcium cycle to generate CO in a higher purity. Techno-economic assessment of the proposed system was conducted to evaluate its efficiency and economic competitiveness. Studies revealed that the optimal molar ratios of oxygen carrier (OC)/NG and steam/NG for reforming were recommended to be 1.7 and 1.0 respectively. The heat integration within CLC and SECLRHC units can be achieved by circulating hot OCs. The desired temperatures of fuel reactor (FR) and reforming reactor (RR) should be 850 °C and 600 °C respectively. The heat coupling between CLC and SECLRHC units can be realized via a jacket-type reactor and the NG split ratio for reforming and combustion was 0.53:0.47. Under the optimal conditions the H2 purity the H2 yield and the CH4 conversion efficiency were 98.76% 2.31 mol mol-1 and 97.96% respectively. The carbon and hydrogen utilization efficiency respectively were 58.60% and 72.45% in terms of the total hydrogen in both steam and NG. The exergy efficiency of the overall process reached 70.28%. In terms of the conventional plant capacity (75×103 t y-1 ) and current raw materials price (2500 $ t-1 ) the payback period can be 6.2 years and the IRR would be 11.5 demonstrating an economically feasible and risk resistant capability.
Renewable Methanol Synthesis
Oct 2019
Publication
Renewable methanol production is an emerging technology that bridges the gap in the shift from fossil fuel to renewable energy. Two thirds of the global emission of CO2 stems from humanity’s increasing energy need from fossil fuels. Renewable energy mainly from solar and wind energy suffers from supply intermittency which current grid infrastructures cannot accommodate. Excess renewable energy can be harnessed to power the electrolysis of water to produce hydrogen which can be used in the catalytic hydrogenation of waste CO2 to produce renewable methanol. This review considers methanol production in the current context regionally for Europe which is dominated by Germany and globally by China. Appropriate carbon-based feedstock for renewable methanol production is considered as well as state-of-the-art renewable hydrogen production technologies. The economics of renewable methanol production necessitates the consideration of regionally relevant methanol derivatives. The thermodynamics kinetics catalytic reaction mechanism operating conditions and reactor design are reviewed in the context of renewable methanol production to reveal the most up to date understanding.
A Review of Ni Based Powder Catalyst for Urea Oxidation in Assisting Water Splitting Reaction
Jan 2022
Publication
Water splitting has been regarded as a sustainable and environmentally-friendly technique to realize green hydrogen generation while more energy is consumed due to the high overpotentials required for the anode oxygen evolution reaction. Urea electrooxidation an ideal substitute is thus received increasing attention in assisting water-splitting reactions. Note that highly efficient catalysts are still required to drive urea oxidation and the facile generation of high valence state species is significant in the reaction based on the electrochemical-chemical mechanisms. The high cost and rareness make the noble metal catalysts impossible for further consideration in large-scale application. Ni-based catalysts are very promising due to their cheap price facile structure tuning good compatibility and easy active phase formation. In the light of the significant advances made recently herein we reviewed the recent advances of Ni-based powder catalysts for urea oxidation in assisting water-splitting reaction. The fundamental of urea oxidation is firstly presented to clarify the mechanism of urea-assisted water splitting and then the prevailing evaluation indicators are briefly expressed based on the electrochemical measurements. The catalyst design principle including synergistic effect electronic effect defect construction and surface reconstruction as well as the main fabrication approaches are presented and the advances of various Ni-based powder catalysts for urea assisted water splitting are summarized and discussed. The problems and challenges are also concluded for the Ni-based powder catalysts fabrication the performance evaluation and their application. Considering the key influence factors for catalytic process and their application attention should be given to structure-property relationship deciphering novel Ni-based powder catalysts development and their construction in the real device; specifically the effort should be directed to the Ni-based powder catalyst with multi-functions to simultaneously promote the fundamental steps and high anti-corrosion ability by revealing the local structure reconstruction as well as the integration in the practical application. We believe the current summarization will be instructive and helpful for the Ni-based powder catalysts development and understanding their catalytic action for urea-assisted hydrogen generation via water splitting technique.
Strategic Overview on Fuel Cell-Based Systems for Mobility and Electrolytic Cells for Hydrogen Production
Mar 2022
Publication
Given the global effort to embrace research actions and technology enhancement for the energy transition innovative sustainable systems are needed both for energy production and for those sectors that are responsible for high pollution and CO2 emissions. In this context electrolytic cells and fuel cells in their variety and flexibility are energy systems characterized by high efficiency and important performance guaranteeing a sustainable solution for future energy systems and for the circular economy. The scope of this paper is therefore to present the state of the art of such systems. An overview of the electrolyzers for hydrogen production is presented by detailing the level of applications for their different technologies from low-temperature units to high-temperature units the fuel flexibility the electrolysis and co-electrolysis mode and the potential coupling with renewable sources. Fuel cell-based systems are also presented and their application in the mobility sector is investigated by considering road transport with light-duty and heavy-duty applications and marine transport. A comparison with conventional technologies will be also presented providing some hints on the potential applications of electrolytic cells and fuel cell systems given their important contribution to the sustainable and circular economy.
A Comprehensive Review on Recent Advancements in Thermochemical Processes for Clean Hydrogen Production to Decarbonize the Energy Sector
Sep 2022
Publication
Hydrogen is a source of clean energy as it can produce electricity and heat with water as a by-product and no carbon content is emitted when hydrogen is used as burning fuel in a fuel cell. Hydrogen is a potential energy carrier and powerful fuel as it has high flammability fast flame speed no carbon content and no emission of pollutants. Hydrogen production is possible through different technologies by utilizing several feedstock materials but the main concern in recent years is to reduce the emission of carbon dioxide and other greenhouse gases from energy sectors. Hydrogen production by thermochemical conversion of biomass and greenhouse gases has achieved much attention as researchers have developed several novel thermochemical methods which can be operated with low cost and high efficiency in an environmentally friendly way. This review explained the novel technologies which are being developed for thermochemical hydrogen production with minimum or zero carbon emission. The main concern of this paper was to review the advancements in hydrogen production technologies and to discuss different novel catalysts and novel CO2 -absorbent materials which can enhance the hydrogen production rate with zero carbon emission. Recent developments in thermochemical hydrogen production technologies were discussed in this paper. Biomass gasification and pyrolysis steam methane reforming and thermal plasma are promising thermochemical processes which can be further enhanced by using catalysts and sorbents. This paper also reviewed the developments and influences of different catalysts and sorbents to understand their suitability for continuous clean industrial hydrogen production.
Techno-Economic Analysis of Low Carbon Hydrogen Production from Offshore Wind Using Battolyser Technology
Aug 2022
Publication
A battolyser is a combined battery electrolyser in one unit. It is based on flow battery technology and can be adapted to produce hydrogen at a lower efficiency than an electrolyser but without the need for rare and expensive materials. This paper presents a method of determining if a battolyser connected to a wind farm makes economic sense based on stochastic modelling. A range of cost data and operational scenarios are used to establish the impact on the NPV and LCOE of adding a battolyser to a wind farm. The results are compared to adding a battery or an electrolyser to a wind farm. Indications are that it makes economic sense to add a battolyser or battery to a wind farm to use any curtailed wind with calculated LCOE at £56/MWh to £58/MWh and positive NPV over a range of cost scenarios. However electrolysers are still too expensive to make economic sense.
Far Off-shore Wind Energy-based Hydrogen Production: Technological Assessment and Market Valuation Designs
Jan 2020
Publication
This article provides a techno-economic study on coupled offshore wind farm and green hydrogen production via sea water electrolysis (OWF-H2). Offshore wind energy wind farms (OWF) and water electrolysis (WE) technologies are described. MHyWind (the tool used to perform simulations and optimisations of such plants) is presented as well as the models of the main components in the study. Three case studies focus on offshore wind farms either stand-alone or connected to the grid via export cables coupled with a battery and electrolysis systems either offshore or onshore. Exhaustive searches and optimisations performed allowed for rules of thumb to be derived on the sizing of coupled OWF-H2 plants that minimize costs of hydrogen production (LCoH2 in €/kgH2): Non-connected OWF-H2 coupled to a battery offers the lowest LCoH2 without the costs of H2 transportation when compared to cases where the WE is installed onshore and connected to the OWF. Using a simple power distribution heuristic increasing the number of installed WE allows the system to take advantage of more OWF energy but doesn’t improve plant efficiency whereas a battery always does. Finally within the scope of this study it is observed that power ratios of optimized plant architectures (leading to the lowest LCoH2) are between 0.8-0.9 for PWE/POWF and 0.3-0.35 for PBattery/POWF.
A Holistic Consideration of Megawatt Electrolysis as a Key Component of Sector Coupling
May 2022
Publication
In the future hydrogen (H2) will play a significant role in the sustainable supply of energy and raw materials to various sectors. Therefore the electrolysis of water required for industrial‐ scale H2 production represents a key component in the generation of renewable electricity. Within the scope of fundamental research work on cell components for polymer electrolyte membrane (PEM) electrolyzers and application‐oriented living labs an MW electrolysis system was used to further improve industrial‐scale electrolysis technology in terms of its basic structure and systems‐ related integration. The planning of this work as well as the analytical and technical approaches taken along with the essential results of research and development are presented herein. The focus of this study is the test facility for a megawatt PEM electrolysis stack with the presentation of the design processing and assembly of the main components of the facility and stack.
Enhanced Performance and Durability of Low Catalyst Loading PEM Water Electrolyser Based on a Short-side Chain Perfluorosulfonic Ionomer
Sep 2016
Publication
Water electrolysis supplied by renewable energy is the foremost technology for producing ‘‘green” hydrogen for fuel cell vehicles. In addition the ability to rapidly follow an intermittent load makes electrolysis an ideal solution for grid-balancing caused by differences in supply and demand for energy generation and consumption. Membrane-electrode assemblies (MEAs) designed for polymer electrolyte membrane (PEM) water electrolysis based on a novel short-side chain (SSC) perfluorosulfonic acid (PFSA) membrane Aquivion with various cathode and anode noble metal loadings were investigated in terms of both performance and durability. Utilizing a nanosized Ir0.7Ru0.3O solid solution anode catalyst and a supported Pt/C cathode catalyst in combination with the Aquivion membrane gave excellent electrolysis performances exceeding 3.2 A cm-2 at 1.8 V terminal cell voltage ( 80% efficiency) at 90 ºC in the presence of a total catalyst loading of 1.6 mg cm−2. A very small loss of efficiency corresponding to 30 mV voltage increase was recorded at 3 A cm 2 using a total noble metal catalyst loading of less than 0.5 mg cm−2 (compared to the industry standard of 2 mg cm−2). Steady-state durability tests carried out for 1000 h at 1 A cm -2 showed excellent stability for the MEA with total noble metal catalyst loading of 1.6 mg cm−2 (cell voltage increase 5 lV/h). Moderate degradation rate (cell voltage increase 15 lV/h) was recorded for the low loading 0.5 mg cm-2 MEA. Similar stability characteristics were observed in durability tests at 3 A cm−2. These high performance and stability characteristics were attributed to the enhanced proton conductivity and good stability of the novel membrane the optimized structural properties of the the enhanced proton conductivity and good stability of the novel membrane the optimized structural properties of the the enhanced proton conductivity and good stability of the novel membrane the optimized structural properties of the Ir and Ru oxide solid solution and the enrichment of Ir species on the surface for the anodic catalyst.
Electric Field Effects on Photoelectrochemical Water Splitting: Perspectives and Outlook
Feb 2022
Publication
The grand challenges in renewable energy lie in our ability to comprehend efficient energy conversion systems together with dealing with the problem of intermittency via scalable energy storage systems. Relatively little progress has been made on this at grid scale and two overriding challenges still need to be addressed: (i) limiting damage to the environment and (ii) the question of environmentally friendly energy conversion. The present review focuses on a novel route for producing hydrogen the ultimate clean fuel from the Sun and renewable energy source. Hydrogen can be produced by light-driven photoelectrochemical (PEC) water splitting but it is very inefficient; rather we focus here on how electric fields can be applied to metal oxide/water systems in tailoring the interplay with their intrinsic electric fields and in how this can alter and boost PEC activity drawing both on experiment and non-equilibrium molecular simulation.
Hydrogen Production in Methane Decomposition Reactor Using Solar Thermal Energy
Nov 2021
Publication
This study investigates the decomposition of methane using solar thermal energy as a heat source. Instead of the direct thermal decomposition of the methane at a temperature of 1200 ◦C or higher a catalyst coated with carbon black on a metal foam was used to lower the temperature and activation energy required for the reaction and to increase the yield. To supply solar heat during the reaction a reactor suitable for a solar concentrating system was developed. In this process a direct heating type reactor with quartz was initially applied and a number of problems were identified. An indirect heating type reactor with an insulated cavity and a rotating part was subsequently developed followed by a thermal barrier coating application. Methane decomposition experiments were conducted in a 40 kW solar furnace at the Korea Institute of Energy Research. Conversion rates of 96.7% and 82.6% were achieved when the methane flow rate was 20 L/min and 40 L/min respectively.
Green Hydrogen: A New Flexibility Source for Security Constrained Scheduling of Power Systems with Renewable Energies
Apr 2021
Publication
Green hydrogen i.e. the hydrogen generated from renewable energy sources (RES) will significantly contribute to a successful energy transition. Besides to facilitate the integration and storage of RES this promising energy carrier is well capable to efficiently link various energy sectors. By introduction of green hydrogen as a new flexibility source to power systems it is necessary to investigate its possible impacts on the generation scheduling and power system security. In this paper a security-constrained multi-period optimal power flow (SC-MPOPF) model is developed aiming to determine the optimal hourly dispatch of generators as well as power to hydrogen (P2H) units in the presence of large-scale renewable energy sources (RES). The proposed model characterizes the P2H demand flexibility in the proposed SC-MPOPF model taking into account the electrolyzer behavior reactive power support of P2H demands and hydrogen storage capability. The developed SC-MPOPF model is applied to IEEE 39-bus system and the obtained numerical results demonstrate the role of P2H flexibility on cost as well as RES's power curtailment reduction.
A Production and Delivery Model of Hydrogen from Solar Thermal Energy in the United Arab Emirates
May 2022
Publication
Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a good fit for solar technologies such as concentrated solar power and photovoltaics. However a thorough comparison between the two solar technologies as well as investigating the infrastructure of the United Arab Emirates for a well-to-ship hydrogen pathway is yet to be fully carried out. Therefore in this study we aim to provide a full model for solar hydrogen production and delivery by evaluating the potential of concentrated solar power and photovoltaics in the UAE then comparing two different pathways for hydrogen delivery based on the location of hydrogen production sites. A Solid Oxide Cell Electrolyzer (SOEC) is used for technical comparison while the shortest routes for hydrogen transport were analyzed using Geographical Information System (GIS). The results show that CSP technology coupled with SOEC is the most favorable pathway for large-scale hydrogen from solar energy production in the UAE for export purposes. Although PV has a slightly higher electricity potential compared to CSP around 42 GWh/km2 to 41.1 GWh/km2 respectively CSP show the highest productions rates of over 6 megatons of hydrogen when the electrolyzer is placed at the same site as the CSP plant while PV generates 5.15 megatons when hydrogen is produced at the same site with PV plants; meanwhile hydrogen from PV and CSP shows similar levels of 4.8 and 4.6 megatons of hydrogen respectively when electrolyzers are placed at port sites. Even considering the constraints in the UAE’s infrastructure and suggesting new shorter electrical transmission lines that could save up to 0.1 megatons of hydrogen in the second pathway production at the same site with CSP is still the most advantageous scenario.
Insights into the Principles, Design Methodology and Applications of Electrocatalysts Towards Hydrogen Evolution Reaction
Apr 2021
Publication
The electrolysis of water for sustainable hydrogen producing is a crucial segment of various emerging clean-energy technologies. However pursuing an efficient and cheap alternative catalyst to substitute state-of-the-art platinum-group electrocatalysts remains a prerequisite for the commercialization of this technology. Typically precious-metal-free catalysts have always much lower activities towards hydrogen production than that of Pt-group catalysts. To explore high-performance catalysts maximally exposed active sites rapid charge transfer ability and desirable electronic configuration are essentially demanded. Herein the fundamentals of hydrogen evolution reaction will be briefly described and the main focus will be on the interfacial engineering strategies by means of constructing defect structure creating heterojunction phase engineering lattice strain control designing hierarchical architecture and doping heteroatoms to effectively proliferate the catalytic active sites facilitate the electron diffusion and regulate the electronic configuration of numerous transition metals and their nitrides carbides sulfides phosphides as well as oxides achieving a benchmark performance of platinum-free electrocatalysts for the hydrogen evolution reaction. This review unambiguously offers proof that the conventional cheap and earth-abundant transition metal-based substances can be translated into an active water splitting catalyst by the rational and controllable interfacial designing.
Efficient Plasma Technology for the Production of Green Hydrogen from Ethanol and Water
Apr 2022
Publication
This study concerns the production of hydrogen from a mixture of ethanol and water. The process was conducted in plasma generated by a spark discharge. The substrates were introduced in the liquid phase into the reactor. The gaseous products formed in the spark reactor were hydrogen carbon monoxide carbon dioxide methane acetylene and ethylene. Coke was also produced. The energy efficiency of hydrogen production was 27 mol(H2 )/kWh and it was 36% of the theoretical energy efficiency. The high value of the energy efficiency of hydrogen production was obtained with relatively high ethanol conversion (63%). In the spark discharge it was possible to conduct the process under conditions in which the ethanol conversion reached 95%. However this entailed higher energy consumption and reduced the energy efficiency of hydrogen production to 8.8 mol(H2 )/kWh. Hydrogen production increased with increasing discharge power and feed stream. However the hydrogen concentration was very high under all tested conditions and ranged from 57.5 to 61.5%. This means that the spark reactor is a device that can feed fuel cells the power load of which can fluctuate.
Cotton Stalk Activated Carbon-supported Co–Ce–B Nanoparticles as Efficient Catalysts for Hydrogen Generation Through Hydrolysis of Sodium Borohydride
Nov 2019
Publication
Porous cotton stalk activated carbons (CSAC) were prepared by phosphoric acid activation of cotton stalks in a fluidized bed. The CSAC-supported Co–B and Co–Ce–B catalysts were prepared by the impregnation-chemical reduction method. The samples were characterized by the nitrogen adsorption XRD FTIR and TEM measurements. The effects of the sodium borohydride (NaBH4) and sodium hydroxide (NaOH) concentrations reaction temperature and recyclability on the rate of NaBH4 hydrolysis over the CSAC-supported Co–Ce–B catalysts were systematically investigated. The results showed that the agglomeration of the Co–Ce–B nanoclusters on the CSAC support surface was significantly reduced with the introduction of cerium. The CSAC-supported Co–Ce–B catalyst exhibited superior catalytic activity and the average hydrogen generation rate was 16.42 L min−1 g−1 Co at 25°C which is higher than the most reported cobalt-based catalysts. The catalytic hydrolysis of NaBH4 was zero order with respect to the NaBH4 concentration and the hydrogen generation rate decreased with the increase in the NaOH concentration. The activation energy of the hydrogen generation reaction on the prepared catalyst was estimated to be 48.22 kJ mol−1. A kinetic rate equation was also proposed.
Water Electrolysis for the Production of Hydrogen to Be Employed in the Ironmaking and Steelmaking Industry
Nov 2021
Publication
The way to decarbonization will be characterized by the huge production of hydrogen through sustainable routes. Thus the basic production way is water electrolysis sustained by renewable energy sources allowing for obtaining “green hydrogen”. The present paper reviews the main available technologies for the water electrolysis finalized to the hydrogen production. We describe the fundamental of water electrolysis and the problems related to purification and/or desalinization of water before electrolysis. As a matter of fact we describe the energy efficiency issues with particular attention to the potential application in the steel industry. The fundamental aspects related to the choice of high-temperature or low-temperature technologies are analyzed.
Analyzing the Necessity of Hydrogen Imports for Net-zero Emission Scenarios in Japan
Jun 2021
Publication
With Japan’s current plans to reach a fully decarbonized society by 2050 and establish a hydrogen society substantial changes to its energy system need to be made. Due to the limited land availability in Japan significant amounts of hydrogen are planned to be imported to reach both targets. In this paper a novel stochastic version of the open-source multi-sectoral Global Energy System Model in conjunction with a power system dispatch model is used to analyze the impacts of both availability and price of hydrogen imports on the transformation of the Japanese energy system considering a net-zero emission target. This analysis highlights that hydrogen poses a valuable resource in specific sectors of the energy system. Therefore importing hydrogen can indeed positively impact energy system developments although up to 19mt of hydrogen will be imported in the case with the cheapest available hydrogen. In contrast without any hydrogen imports power demand nearly doubles in 2050 compared to 2019 due to extensive electrification in non-electricity sectors. However hydrogen imports are not necessarily required to reach net-zero emissions. In all cases however large-scale investments into renewable energy sources need to be made.
Everything About Hydrogen Podcast: ITM Power
Sep 2019
Publication
On this weeks show we discuss with Graham Cooley the CEO of ITM Power how his company has expanded from a research company on AIM in the early 2000’s to one of the largest electrolyser manufacturers in the world. On the show we also ask Graham to talk about how the hydrogen market has evolved where he sees the potential growth trajectory for the industry and how ITM sees its role within this space.
The podcast can be found on their website
The podcast can be found on their website
Hydrogen Production by Water Electrolysis with Low Power and High Efficiency Based on Pre‐Magnetic Polarization
Mar 2022
Publication
In this paper a method of efficient hydrogen production using low‐power electrolysis based on pre‐magnetic polarization was proposed in order to improve the rate of hydrogen produc‐ tion by water electrolysis with reduced energy consumption molecular polarity and stress–strain characteristics of distilled water under the condition of a pre‐magnetic field. By constructing a mi‐ crophysical model of hydrogen proton energy‐level transition and a macroscopic mathematical model corresponding to magnetization vector‐polarization hydrogen proton concentration in the pre‐magnetic field the ionic conductivity electrolyte current density interelectrode voltage and hydrogen production efficiency under a varying magnetic field were qualitatively and quantita‐ tively analyzed. In addition an adjustable pre‐magnetic polarization hydrolyzing hydrogen pro‐ duction test platform was set up to verify the effectiveness of the proposed method. The repeated test results within a magnetic field strength range of 0–10000 GS showed that the conductivity of distilled water after pre‐magnetic polarization treatment increased by 2–3 times the electrolytic current density of the PEM (Proton Exchange Membrane) increased with increasing magnetic field strength the voltage between the poles continuously decreased and the hydrogen production rate was significantly improved. When the magnetic field strength reached 10000 GS the rate of hydro‐ gen production by the electrolysis of distilled water increased by 15%–20% within a certain period of time.
Dynamic Simulation and Thermoeconomic Analysis of a Hybrid Renewable System Based on PV and Fuel Cell Coupled with Hydrogen Storage
Nov 2021
Publication
The production of “green hydrogen” is currently one of the hottest topics in the field of renewable energy systems research. Hydrogen storage is also becoming more and more attractive as a flexible solution to mitigate the power fluctuations of solar energy systems. The most promising technology for electricity-to-hydrogen conversion and vice versa is the reversible solid-oxide cell (SOC). This device is still very expensive but it exhibits excellent performance under dynamic operating conditions compared to the competing devices. This work presents the dynamic simulation of a prototypal renewable plant combining a 50 kW photovoltaic (PV) field with a 50 kW solid-oxide electrolyzer cell (SOEC) and a compressed hydrogen tank. The electricity is used to meet the energy demand of a dwelling located in the area of Campi Flegrei (Naples). The SOC efficiency is simulated by developing a mathematical model in MATLAB®. The model also calculates the cell operating temperature as a function of the input current. Once the optimal values of the operating parameters of the SOC are calculated the model is integrated in the transient system simulation tool (TRNSYS) for dynamic analysis. Furthermore this work presents a parametric analysis of the hydrogen storage system (HSS). The results of the energy and environmental analyses show that the proposed system can reach a primary energy saving by 70% and an amount of saved CO2 of 28 tons/year. Some possible future market scenarios are considered for the economic analysis. In the most realistic case the optimal configuration shows a simple pay back lower than 10 years and a profit index of 46%.
Techno-economic Analysis of Hydrogen Electrolysis from Off-Grid Stand-Alone Photovoltaics Incorporating Uncertainty Analysis
Oct 2020
Publication
Solar-driven electrolysis of water to generate hydrogen is emerging as a viable strategy to decarbonize the global energy economy. However this direction is more expensive than traditional fossil fuel generation of hydrogen and effective pathways to lower this cost need to be identified. Here we report a Monte Carlo approach to explore a wide range of input assumptions to identify key cost drivers targets and localized conditions necessary for competitive stand-alone dedicated PV powered hydrogen electrolysis. We determine the levelized cost of hydrogen (LCOH) considering historical weather data for specific locations to model our PV system and optimize its size compared to the electrolyzer. This analysis and its methods show the potential for green hydrogen production using off-grid PV shows the merits of remote systems in areas of high solar resource and provides cost and performance targets for electrolyzer technologies.
Everything About Hydrogen Podcast: Giga-watt it Takes to Scale Green Hydrogen (and Ammonia)
Feb 2021
Publication
How do we get green hydrogen (and green ammonia) production to scale and make it cost competitive? It's a great question and we ask it all the time on the show. Well Alicia Eastman Co-founder & Managing Director of InterContinental Energy (ICE) may be one of the best authorities in the world on this topic and she joins us on this episode of EAH to tell the team all about her and ICE's work developing the Asian Renewable Energy Hub (AREH). Located in Western Australia the AREH when completed will be the largest renewable energy project by total generation capacity on the planet. At 26 GW it surpasses even the likes of the Three Gorges Dam and will act as a central production and distribution point for huge quantities of clean hydrogen and ammonia for offtakers and customers across APAC and beyond. The AREH is a truly massive project that has global implications for the global energy landscape of the future.
The podcast can be found on their website.
The podcast can be found on their website.
Main Hydrogen Production Processes: An Overview
May 2021
Publication
Due to its characteristics hydrogen is considered the energy carrier of the future. Its use as a fuel generates reduced pollution as if burned it almost exclusively produces water vapor. Hydrogen can be produced from numerous sources both of fossil and renewable origin and with as many production processes which can use renewable or non-renewable energy sources. To achieve carbon neutrality the sources must necessarily be renewable and the production processes themselves must use renewable energy sources. In this review article the main characteristics of the most used hydrogen production methods are summarized mainly focusing on renewable feedstocks furthermore a series of relevant articles published in the last year are reviewed. The production methods are grouped according to the type of energy they use; and at the end of each section the strengths and limitations of the processes are highlighted. The conclusions compare the main characteristics of the production processes studied and contextualize their possible use.
Multi-Criteria Comparative Analysis of Clean Hydrogen Production Scenarios
Aug 2020
Publication
Different hydrogen production scenarios need to be compared in regard to multiple and often distinct aspects. It is well known that hydrogen production technologies based on environmentally-friendly renewable energy sources have higher values of the economic indicators than methods based on fossil fuels. Therefore how should this decision criterion (environmental) prevail over the other types of decision criteria (technical and economic) to make a scenario where hydrogen production only uses renewable energy sources the most attractive option for a decision-maker? This article presents the results of a multi-variant comparative analysis of scenarios to annually produce one million tons of pure hydrogen (99.999%) via electrolysis in Poland. The compared variants were found to differ in terms of electricity sources feeding the electrolyzers. The research demonstrated that the scenario where hydrogen production uses energy from photovoltaics only becomes the best option for the environmental criterion weighting value at 61%. Taking the aging effect of photovoltaic installation (PV) panels and electrolyzers after 10 years of operation into account the limit value of the environmental criterion rises to 63%. The carried out analyses may serve as the basis for the creation of systems supporting the development of clean and green hydrogen production technologies.
Everything About Hydrogen Podcast: Hydrogen: The Next Generation
May 2021
Publication
This is the inaugural episode of the EAH: Deep Dive podcast mini-series! Our first episode features the co-founders of Enapter Vaitea Cowan and Jan Justus-Schmidt. Enapter is a young company that has made a big splash in the hydrogen space with their modular scalable AEM electrolyzer technology. Last year they made headlines with their successful public offering on the DAX and the company is expected to be a the forefront of the hydrogen sector again in 2021 as they begin construction of their mass production facility in Germany and announce the upcoming Generation Hydrogen event on May 19 2021.
The podcast can be found on their website
The podcast can be found on their website
Renewable Power-to-Gas: A Technological and Economic Review
Aug 2015
Publication
The Power-to-Gas (PtG) process chain could play a significant role in the future energy system. Renewable electric energy can be transformed into storable methane via electrolysis and subsequent methanation. This article compares the available electrolysis and methanation technologies with respect to the stringent requirements of the PtG chain such as low CAPEX high efficiency and high flexibility. Three water electrolysis technologies are considered: alkaline electrolysis PEM electrolysis and solid oxide electrolysis. Alkaline electrolysis is currently the cheapest technology; however in the future PEM electrolysis could be better suited for the PtG process chain. Solid oxide electrolysis could also be an option in future especially if heat sources are available. Several different reactor concepts can be used for the methanation reaction. For catalytic methanation typically fixed-bed reactors are used; however novel reactor concepts such as three-phase methanation and micro reactors are currently under development. Another approach is the biochemical conversion. The bioprocess takes place in aqueous solutions and close to ambient temperatures. Finally the whole process chain is discussed. Critical aspects of the PtG process are the availability of CO2 sources the dynamic behaviour of the individual process steps and especially the economics as well as the efficiency.
Instantaneous Hydrogen Production from Ammonia by Non-thermal Arc Plasma Combining with Catalyst
Jul 2021
Publication
Owing to the storage and transportation problems of hydrogen fuel exploring new methods of the realtime hydrogen production from ammonia becomes attractive. In this paper non-thermal arc plasma (NTAP) combining with NiO/Al2O3 catalyst is developed to produce hydrogen from ammonia with high efficiency and large scale. The effects of ammonia gas flow rate and discharge power on the gas temperature electron density the hydrogen production rate and energy efficiency were investigated. Experimental results show that the optical emission spectrum of NTAP working with pure ammonia medium was dominated by the atom spectrum of Hα Hβ and molecular spectrum of NH component. Under the optimum experimental condition of plasma discharge the highest energy efficiency of hydrogen production reached 783.4 L/kW·h at NH3 gas flow rate of 30 SLM. When the catalyst was added and heated by the NTAP simultaneously the energy efficiency further increased to 1080.0 L/kW·h.
Reforming Processes for Syngas Production: A Mini-review on the Current Status, Challenges, and Prospects for Biomass Conversion to Fuels
Mar 2022
Publication
Dedicated bioenergy combined with carbon capture and storage are important elements for the mitigation scenarios to limit the global temperature rise within 1.5 °C. Thus the productions of carbon-negative fuels and chemicals from biomass is a key for accelerating global decarbonisation. The conversion of biomass into syngas has a crucial role in the biomass-based decarbonisation routes. Syngas is an intermediate product for a variety of chemical syntheses to produce hydrogen methanol dimethyl ether jet fuels alkenes etc. The use of biomass-derived syngas has also been seen as promising for the productions of carbon negative metal products. This paper reviews several possible technologies for the production of syngas from biomass especially related to the technological options and challenges of reforming processes. The scope of the review includes partial oxidation (POX) autothermal reforming (ATR) catalytic partial oxidation (CPO) catalytic steam reforming (CSR) and membrane reforming (MR). Special attention is given to the progress of CSR for biomass-derived vapours as it has gained significant interest in recent years. Heat demand and efficiency together with properties of the reformer catalyst were reviewed more deeply in order to understand and propose solutions to the problems that arise by the reforming of biomass-derived vapours and that need to be addressed in order to implement the technology on a big scale.
Hydrogen and Hydrogen-derived Fuels through Methane Decomposition of Natural Gas – GHG Emissions and Costs
May 2020
Publication
Hydrogen can be produced from the decomposition of methane (also called pyrolysis). Many studies assume that this process emits few greenhouse gas (GHG) because the reaction from methane to hydrogen yields only solid carbon and no CO2. This paper assesses the life-cycle GHG emissions and the levelized costs for hydrogen provision from methane decomposition in three configurations (plasma molten metal and thermal gas). The results of these configurations are then compared to electrolysis and steam methane reforming (SMR) with and without CO2capture and storage (CCS). Under the global natural gas supply chain conditions hydrogen from methane decomposition still causes significant GHG emissions between 43 and 97 g CO2-eq./MJ. The bandwidth is predominately determined by the energy source providing the process heat i.e. the lowest emissions are caused by the plasma system using renewable electricity. This configuration shows lower GHG emissions compared to the “classical” SMR (99 g CO2-eq./MJ) but similar emissions to the SMR with CCS (46 g CO2-eq./MJ). However only electrolysis powered with renewable electricity leads to very low GHG emissions (3 g CO2-eq./MJ). Overall the natural gas supply is a decisive factor in determining GHG emissions. A natural gas supply with below-global average GHG emissions can lead to lower GHG emissions of all methane decomposition configurations compared to SMR. Methane decomposition systems (1.6 to 2.2 €/kg H2) produce hydrogen at costs substantially higher compared to SMR (1.0 to 1.2 €/kg) but lower than electrolyser (2.5 to 3.0 €/kg). SMR with CCS has the lowest CO2abatement costs (24 €/t CO2-eq. other > 141 €/t CO2-eq.). Finally fuels derived from different hydrogen supply options are assessed. Substantially lower GHG emissions compared to the fossil reference (natural gas and diesel/gasoline) are only possible if hydrogen from electrolysis powered by renewable energy is used (>90% less). The other hydrogen pathways cause only slightly lower or even higher GHG emissions.
Modelling and Experimental Analysis of a Polymer Electrolyte Membrane Water Electrolysis Cell at Different Operating Temperatures
Nov 2018
Publication
In this paper a simplified model of a Polymer Electrolyte Membrane (PEM) water electrolysis cell is presented and compared with experimental data at 60 ◦C and 80 ◦C. The model utilizes the same modelling approach used in previous work where the electrolyzer cell is divided in four subsections: cathode anode membrane and voltage. The model of the electrodes includes key electrochemical reactions and gas transport mechanism (i.e. H2 O2 and H2O) whereas the model of the membrane includes physical mechanisms such as water diffusion electro osmotic drag and hydraulic pressure. Voltage was modelled including main overpotentials (i.e. activation ohmic concentration). First and second law efficiencies were defined. Key empirical parameters depending on temperature were identified in the activation and ohmic overpotentials. The electrodes reference exchange current densities and change transfer coefficients were related to activation overpotentials whereas hydrogen ion diffusion to Ohmic overvoltages. These model parameters were empirically fitted so that polarization curve obtained by the model predicted well the voltage at different current found by the experimental results. Finally from the efficiency calculation it was shown that at low current densities the electrolyzer cell absorbs heat from the surroundings. The model is not able to describe the transients involved during the cell electrochemical reactions however these processes are assumed relatively fast. For this reason the model can be implemented in system dynamic modelling for hydrogen production and storage where components dynamic is generally slower compared to the cell electrochemical reactions dynamics.
Toward Design of Synergistically Active Carbon-Based Catalysts for Electrocatalytic Hydrogen Evolution
Apr 2014
Publication
Replacement of precious catalyst with cost-effective alternatives would be significantly beneficial for hydrogen production via electrocatalytic hydrogen evolution reaction (HER). All candidates thus far are exclusively metallic catalysts which suffer inherent corrosion and oxidation susceptibility during acidic proton-exchange membrane electrolysis. Herein based on theoretical predictions we designed and synthesized nitrogen (N) and phosphorus (P) dual-doped graphene as a non-metallic electrocatalyst for sustainable and efficient hydrogen production. The N and Phetero-atoms could coactivate the adjacent C atom in the graphene matrix by affecting its valence orbital energy levels to induce a synergistically enhanced reactivity toward HER. As a result the dual-doped graphene showed higher electrocatalytic HER activity than single-doped ones and comparable performance to some of the traditional metallic catalysts.
Finding Synergy Between Renewables and Coal: Flexible Power and Hydrogen Production from Advanced IGCC Plants with Integrated CO2 Capture
Feb 2021
Publication
Variable renewable energy (VRE) has seen rapid growth in recent years. However VRE deployment requires a fleet of dispatchable power plants to supply electricity during periods with limited wind and sunlight. These plants will operate at reduced utilization rates that pose serious economic challenges. To address this challenge this paper presents the techno-economic assessment of flexible power and hydrogen production from integrated gasification combined cycles (IGCC) employing the gas switching combustion (GSC) technology for CO2 capture and membrane assisted water gas shift (MAWGS) reactors for hydrogen production. Three GSC-MAWGS-IGCC plants are evaluated based on different gasification technologies: Shell High Temperature Winkler and GE. These advanced plants are compared to two benchmark IGCC plants one without and one with CO2 capture. All plants utilize state-of-the-art H-class gas turbines and hot gas clean-up for maximum efficiency. Under baseload operation the GSC plants returned CO2 avoidance costs in the range of 24.9–36.9 €/ton compared to 44.3 €/ton for the benchmark. However the major advantage of these plants is evident in the more realistic mid-load scenario. Due to the ability to keep operating and sell hydrogen to the market during times of abundant wind and sun the best GSC plants offer a 6–11%-point higher annual rate of return than the benchmark plant with CO2 capture. This large economic advantage shows that the flexible GSC plants are a promising option for balancing VRE provided a market for the generated clean hydrogen exists.
On the Climate Impacts of Blue Hydrogen Production
Nov 2021
Publication
Natural gas based hydrogen production with carbon capture and storage is referred to as blue hydrogen. If substantial amounts of CO2 from natural gas reforming are captured and permanently stored such hydrogen could be a low-carbon energy carrier. However recent research raises questions about the effective climate impacts of blue hydrogen from a life cycle perspective. Our analysis sheds light on the relevant issues and provides a balanced perspective on the impacts on climate change associated with blue hydrogen. We show that such impacts may indeed vary over large ranges and depend on only a few key parameters: the methane emission rate of the natural gas supply chain the CO2 removal rate at the hydrogen production plant and the global warming metric applied. State-of-the-art reforming with high CO2 capture rates combined with natural gas supply featuring low methane emissions does indeed allow for substantial reduction of greenhouse gas emissions compared to both conventional natural gas reforming and direct combustion of natural gas. Under such conditions blue hydrogen is compatible with low-carbon economies and exhibits climate change impacts at the upper end of the range of those caused by hydrogen production from renewable-based electricity. However neither current blue nor green hydrogen production pathways render fully “net-zero” hydrogen without additional CO2 removal.
Photocatalytic Hydrogen Production by Photo-Reforming of Methanol with One-pot Synthesized Pt-containing TiO2 Photocatalysts
Jul 2019
Publication
Functionalization of semiconductors by metallic nanoparticle is considered to be one of the most effective procedure to improve photocatalytic hydrogen production. Photodeposition is frequently used for functionalization but particle sizes and dispersions are still difficult to control. Here Pt functionalization is achieved in a one-pot synthesis. The as-prepared samples are compared to reference materials prepared by conventional photodeposition and our results confirm that small and well-dispersed nanoparticles with superior stability are obtained by one-pot synthesis. The enhanced stability is attributed to a limited leaching of Pt nanoparticles during illumination likely caused by the preferable interaction of small well dispersed Pt nanoparticles with the TiO2 support material. In addition our results demonstrate that Na-residues are detrimental for the photocatalytic performance and washing in acidic solution is mandatory to effectively reduce the sodium contamination.
Prediction of Gaseous Products from Refuse Derived Fuel Pyrolysis Using Chemical Modelling Software - Ansys Chemkin-Pro
Nov 2019
Publication
There can be observed global interest in waste pyrolysis technology due to low costs and availability of raw materials. At the same time there is a literature gap in forecasting environmental effects of thermal waste treatment installations. In the article was modelled the chemical composition of pyrolysis gas with main focus on the problem in terms of environmental hazards. Not only RDF fuel was analysed but also selected waste fractions included in its composition. This approach provided comprehensive knowledge about the chemical composition of gaseous pyrolysis products which is important from the point of view of the heterogeneity of RDF fuel. The main goal of this article was to focus on the utilitarian aspect of the obtained calculation results. Final results can be the basis for estimating ecological effects both for existing and newly designed installations.
Pyrolysis process was modelled using Ansys Chemkin-Pro software. The investigation of the process were carried out for five different temperatures (700 750 800 850 and 900 °C). As an output the mole fraction of H2 H2O CH4 C2H2C2H4 C3H6 C3H8 CO CO2 HCl and H2S were presented. Additionally the reaction pathways for selected material were presented.
Based on obtained results it was established that the residence time did not influenced on the concentration of products contrary to temperature. The chemical composition of pyrolytic gas is closely related to wastes origin. The application of Chemkin-Pro allowed the calculation of formation for each products at different temperatures and formulation of hypotheses on the reaction pathways involved during pyrolysis process. Further based on the obtained results confirmed the possibilities of using pyrolysis gas from RDF as a substitute for natural gas in energy consumption sectors. Optimization of the process can be conducted with low financial outlays and reliable results by using calculation tools. Moreover it can be predicted negative impact of obtained products on the future installation.
Pyrolysis process was modelled using Ansys Chemkin-Pro software. The investigation of the process were carried out for five different temperatures (700 750 800 850 and 900 °C). As an output the mole fraction of H2 H2O CH4 C2H2C2H4 C3H6 C3H8 CO CO2 HCl and H2S were presented. Additionally the reaction pathways for selected material were presented.
Based on obtained results it was established that the residence time did not influenced on the concentration of products contrary to temperature. The chemical composition of pyrolytic gas is closely related to wastes origin. The application of Chemkin-Pro allowed the calculation of formation for each products at different temperatures and formulation of hypotheses on the reaction pathways involved during pyrolysis process. Further based on the obtained results confirmed the possibilities of using pyrolysis gas from RDF as a substitute for natural gas in energy consumption sectors. Optimization of the process can be conducted with low financial outlays and reliable results by using calculation tools. Moreover it can be predicted negative impact of obtained products on the future installation.
Renewable Hydrogen Production from Butanol Steam Reforming over Nickel Catalysts Promoted by Lanthanides
Oct 2021
Publication
Hydrogen is mainly produced by steam reforming of natural gas a non-renewable resource. Alternative and renewable routes for hydrogen production play an important role in reducing dependence on oil and minimizing the emission of greenhouse gases. In this work butanol a model compound of bio-oil was employed for hydrogen production by steam reforming. The reaction was evaluated for 30 h in a tubular quartz reactor at 500 ◦C atmospheric pressure GHSV of 500000 h−1 and an aqueous solution feed of 10% v/v butanol. For this reaction catalysts with 20 wt.% NiO were prepared by wet impregnation using three supports: γ-alumina and alumina modified with 10 wt.% of cerium and lanthanum oxides. Both promoters increased the reduction degree of the catalysts and decreased catalyst acidity which is closely related to coke formation and deactivation. Ni/La2O3– Al2O3 presented a higher nickel dispersion (14.6%) which combined with other properties led to a higher stability higher mean hydrogen yield (71%) and lower coke formation per mass (56%). On the other hand the nonpromoted catalyst suffered a significant deactivation associated with coke formation favored by its highest acidity (3.1 µmol m−2 ).
Pyrolysis-gasification of Wastes Plastics for Syngas Production Using Metal Modified Zeolite Catalysts Under Different Ratio of Nitrogen/Oxygen
Jun 2020
Publication
The aim of this study was the syngas production by the gasification of plastic waste (polyethylene polypropylene and terephthalate polyethylene). Ca Ce La Mg and Mn were used to promote the Ni/ZSM-5 catalyst in order to enhance the production of higher syngas yield. The modified catalysts can enhanced the reaction rate of the pyrolysis process and resulting in high syngas in the product yields. Especially cerium lanthanum promoted catalysts can enhance the yield of syngas. The effect of the reaction temperature and nitrogen/oxygen ratio of the carrier gas was also investigated. The maximum syngas production was obtained with lanthanum catalyst (112.2 mmol/g (95%N2 and 5%O2) and 130.7 mmol/g (90%N2 and 10%O2) at 850 °C. Less carbon depositions was found at 850 °C or even by the using of catalyst and more oxygen in the carrier gas. The oxygen content of the pyrolysis-gasification atmosphere had a key role to the syngas yield and affects significantly the carbon-monoxide/carbon-dioxide ratio. Catalysts can also accelerate the methanization reactions and isomerize the main carbon frame. Increasing in both temperature and oxygen in the atmosphere led to higher n-paraffin/n-olefin ratio and more multi-ring aromatic hydrocarbons in pyrolysis oils. The concentration of hydrocarbons containing oxygen and branched compounds was also significantly affected by catalysts.
Hydrogen Production Methods Based on Solar and Wind Energy: A Review
Jan 2023
Publication
Several research works have investigated the direct supply of renewable electricity to electrolysis particularly from photovoltaic (PV) and wind generator (WG) systems. Hydrogen (H2 ) production based on solar energy is considered to be the newest solution for sustainable energy. Different technologies based on solar energy which allow hydrogen production are presented to study their benefits and inconveniences. The technology of water decomposition based on renewable energy sources to produce hydrogen can be achieved by different processes (photochemical systems; photocatalysis systems photo-electrolysis systems bio-photolysis systems thermolysis systems thermochemical cycles steam electrolysis hybrid processes and concentrated solar energy systems). A comparison of the different methods for hydrogen production based on PV and WG systems was given in this study. A comparative study of different types of electrolyzers was also presented and discussed. Finally an economic assessment of green hydrogen production is given. The hydrogen production cost depends on several factors such as renewable energy sources electrolysis type weather conditions installation cost and the productivity of hydrogen per day. PV/H2 and wind/H2 systems are both suitable in remote and arid areas. Minimum maintenance is required and a power cycle is not needed to produce electricity. The concentrated CSP/H2 system needs a power cycle. The hydrogen production cost is higher if using wind/H2 rather than PV/H2 . The green energy sources are useful for multiple applications such as hydrogen production cooling systems heating and water desalination.
Development of Water Electrolysis in the European Union
Feb 2014
Publication
In view of the recent interest in the transformation of renewable energy into a new energy vector that did not produce by combustion greenhouse gases emissions the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) commissioned this report to a consultancy to get a better understanding of the industrial perspectives of water electrolysis in Europe. and the role that public support has in that evolution.
Novel Biofuel Cell Using Hydrogen Generation of Photosynthesis
Nov 2020
Publication
Energies based on biomaterials attract a lot of interest as next-generation energy because biomaterials are environmentally friendly materials and abundant in nature. Fuel cells are also known as the clean and important next-generation source of energy. In the present study to develop the fuel cell based on biomaterials a novel biofuel cell which consists of collagen electrolyte and the hydrogen fuel generated from photochemical system II (PSII) in photosynthesis has been fabricated and its property has been investigated. It was found that the PSII solution in which PSII was extracted from the thylakoid membrane using a surfactant generates hydrogen by the irradiation of light. The typical hydrogen-generating rate is approximately 7.41 × 1014 molecules/s for the light intensity of 0.5 mW/cm2 for the PSII solution of 5 mL. The biofuel cell using the PSII solution as the fuel exhibited approximately 0.12 mW/cm2 . This result indicates that the fuel cell using the collagen electrolyte and the hydrogen fuel generated from PSII solution becomes the new type of biofuel cell and will lead to the development of the next-generation energy
Ultra-clean Hydrogen Production by Ammonia Decomposition
Jan 2016
Publication
A rigorous heterogeneous mathematical model is used to simulate a cascade of multi-stage fixed bed membrane reactors (MSFBMR) with inter-stage heating and fresh sweep gas for the decomposition of ammonia to produce high purity hydrogen suitable for the PEM fuel cells. Different reactor configurations are compared. The comparison between a single fixed bed reactor (FBR) and a single fixed bed membrane reactor (FBMR) shows that the FBMR is superior to the FBR and gives 60.48% ammonia conversion higher than the FBR. However 20.91% exit ammonia conversion obtained by the FBMR is considered to be poor. The FBMR is limited by the kinetics at low temperatures. The numerical results show that the MSFBMR of four beds achieve 100.0% ammonia conversion. It was found that the membrane plays the prime role in the displacement of the thermodynamic equilibrium. The results also show that a linear relationship exists between the number of beds and the feed temperature and a correlation has been developed. A critical point for an effective hydrogen permeation zone has been identified. It is observed that the diffusion limitation is confined to a slim region at the entrance of the reactor. It is also observed that the heat load assumes a maximum inflection point and explanations offered. The results show that the multi-stage configuration has a promising potential to be applied successfully on-site for ultra-clean hydrogen production.
Transitioning Remote Arctic Settlements to Renewable Energy Systems – A Modelling Study of Longyearbyen, Svalbard
Nov 2019
Publication
As transitioning away from fossil fuels to renewable energy sources comes on the agenda for a range of energy systems energy modelling tools can provide useful insights. If large parts of the energy system turns out to be based on variable renewables an accurate representation of their short-term variability in such models is crucial. In this paper we have developed a stochastic long-term energy model and applied it to an isolated Arctic settlement as a challenging and realistic test case. Our findings suggest that the stochastic modelling approach is critical in particular for studies of remote Arctic energy systems. Furthermore the results from a case study of the Norwegian settlement of Longyearbyen suggest that transitioning to a system based on renewable energy sources is feasible. We recommend that a solution based mainly on renewable power generation but also including energy storage import of hydrogen and adequate back-up capacity is taken into consideration when planning the future of remote Arctic settlements.
Hydrogen Production Technologies Overview
Jan 2019
Publication
Hydrogen energy became the most significant energy as the current demand gradually starts to increase. Hydrogen energy is an important key solution to tackle the global temperature rise. The key important factor of hydrogen production is the hydrogen economy. Hydrogen production technologies are commercially available while some of these technologies are still under development. This paper reviews the hydrogen production technologies from both fossil and non-fossil fuels such as (steam reforming partial oxidation auto thermal pyrolysis and plasma technology). Additionally water electrolysis technology was reviewed. Water electrolysis can be combined with the renewable energy to get eco-friendly technology. Currently the maximum hydrogen fuel productions were registered from the steam reforming gasification and partial oxidation technologies using fossil fuels. These technologies have different challenges such as the total energy consumption and carbon emissions to the environment are still too high. A novel non-fossil fuel method [ammonia NH3] for hydrogen production using plasma technology was reviewed. Ammonia decomposition using plasma technology without and with a catalyst to produce pure hydrogen was considered as compared case studies. It was showed that the efficiency of ammonia decomposition using the catalyst was higher than ammonia decomposition without the catalyst. The maximum hydrogen energy efficiency obtained from the developed ammonia decomposition system was 28.3% with a hydrogen purity of 99.99%. The development of ammonia decomposition processes is continues for hydrogen production and it will likely become commercial and be used as a pure hydrogen energy source.
Everything About Hydrogen Podcast: Scaling Clean Hydrogen Production
Dec 2021
Publication
Today we are joined by our good friends from Enapter. The company is a leader in the clean hydrogen sector focused on AEM electrolyzer technology and innovative software solutions that make it possible to rapidly deploy and scale hydrogen production assets. For those who follow the hydrogen sector regularly it’s been hard not to hear Enapter-related news in 2021 and its impressive trajectory as they have gone public announced the plans for a brand new production facility in Germany (on which they have now begun construction) and most recently the announcement that Enapter was selected as the winner of the prestigious Earthshot prize. To do that we are absolutely delighted to have with us all the way from his home base in Thailand Thomas Chrometzka Chief Strategy Officer at Enapter and one of the people that we enjoy having on the show so much that we have brought him back again to fill us in on what he and Enapter are up to and what they have planned for the future of hydrogen.
The podcast can be found on their website
The podcast can be found on their website
Microalgal Hydrogen Production in Relation to Other Biomass‐Based Technologies—A Review
Sep 2021
Publication
Hydrogen is an environmentally friendly biofuel which if widely used could reduce atmospheric carbon dioxide emissions. The main barrier to the widespread use of hydrogen for power generation is the lack of technologically feasible and—more importantly—cost‐effective methods of production and storage. So far hydrogen has been produced using thermochemical methods (such as gasification pyrolysis or water electrolysis) and biological methods (most of which involve anaerobic digestion and photofermentation) with conventional fuels waste or dedicated crop biomass used as a feedstock. Microalgae possess very high photosynthetic efficiency can rapidly build biomass and possess other beneficial properties which is why they are considered to be one of the strongest contenders among biohydrogen production technologies. This review gives an account of present knowledge on microalgal hydrogen production and compares it with the other available biofuel production technologies.
In Situ Neutron Radiography Investigations of Hydrogen Related Processes in Zirconium Alloys
Jun 2021
Publication
In situ neutron radiography experiments can provide information about diffusive processes and the kinetics of chemical reactions. The paper discusses requirements for such investigations. As examples of the zirconium alloy Zircaloy-4 the hydrogen diffusion the hydrogen uptake during high-temperature oxidation in steam and the reaction in nitrogen/steam and air/steam atmospheres results of in situ neutron radiography investigations are reviewed and their benefit is discussed.
Remarkable Visible-light Induced Hydrogen Generation with ZnIn2S4 Microspheres/CuInS2 Quantum Dots Photocatalytic System
Oct 2020
Publication
A new and active material in the form of ZnIn2S4 microspheres decorated by CuInS2 quantum dots have been obtained by hydrothermal method for the first time. The optimum amount of CuInS2 quantum dots (1.13 wt.%) introduced into rection medium during ZnIn2S4 microspheres synthesis increased the photocatalytic H2 generation rate by 2.5 times than that of bare ZnIn2S4 photocatalysis under visible light irradiation. This sample exhibited strong photoactivity in the extended visible range up to 540 nm with 30.6% apparent quantum efficiency (λ = 420 nm).
Electric Load Influence on Performances of a Composite Plant for Hydrogen Production from RES and its Conversion in Electricity
Nov 2019
Publication
The analysis here presented investigates the influence of electrical load on the operational performances of a plant for hydrogen production from solar energy and its conversion in electricity via a fuel cell. The plant is an actual one currently under construction in Reggio Calabria (Italy) at the site of the Mediterranean university campus; it is composed of a Renewable Energy Source (RES) section (photovoltaic panels) a hydrogen production section and a fuel cell power section feeding the electrical energy demand of the load. Two different load configurations have been analysed and simulations have been carried out through HomerTM simulation code. Results allow interesting conclusions regarding the plant operation to be drawn. The study could have a remarkable role in supporting further research activities aimed at the assessment of the optimal configuration of this type of pioneering plants designed for feeding electrical loads possibly in a self-sufficient way.
Gasification of Solid Fuels (Coal, Biomass and MSW): Overview, Challenges and Mitigation Strategies
Jun 2022
Publication
Currently hydrogen energy is the most promising energy vector while gasification is one of the major routes for its production. However gasification suffers from various issues including slower carbon conversion poor syngas quality lower heating value and higher emissions. Multiple factors affect gasification performance such as the selection of gasifiers feedstock’s physicochemical properties and operating conditions. In this review the status of gasification key gasifier technologies and the effect of solid-fuel (i.e. coal biomass and MSW) properties on gasification performance are reviewed critically. Based on the current review the co-gasification of coal biomass and solid waste along with a partial utilisation of CO2 as a reactant are suggested. Furthermore a technological breakthrough in carbon capture and sequestration is needed to make it industrially viable
Everything About Hydrogen Podcast: Could Electrolysers Replicate Moore's Law?
Apr 2020
Publication
On this weeks episode the team are talking all things hydrogen with Sebastian-Justus Schmidt Chairman of Enapter and Thomas Chrometzka Head of Strategy at Enapter. On the show we discuss Enapter’s Anion Exchange Membrane (AEM) electrolyser and why Enapter believe that their modular electrolyser approach will revolutionise the cost of green hydrogen. We also discuss the wide array of use cases and sectors that Enapter are already working with to provide their solution as well as their view on where the current barriers exist for the hydrogen market. All this and more on the show!
The podcast can be found on their website
The podcast can be found on their website
Dedicated Large-scale Floating Offshore Wind to Hydrogen: Assessing Design Variables in Proposed Typologies
Mar 2022
Publication
To achieve the Net-Zero Emissions goal by 2050 a major upscale in green hydrogen needs to be achieved; this will also facilitate use of renewable electricity as a source of decarbonised fuel in hard-to-abate sectors such as industry and transport. Nearly 80% of the world’s offshore wind resource is in waters deeper than 60 m where bottom-fixed wind turbines are not feasible. This creates a significant opportunity to couple the high capacity factor floating offshore wind and green hydrogen. In this paper we consider dedicated large-scale floating offshore wind farms for hydrogen production with three coupling typologies; (i) centralised onshore electrolysis (ii) decentralised offshore electrolysis and (iii) centralised offshore electrolysis. The typology design is based on variables including for: electrolyser technology; floating wind platform; and energy transmission vector (electrical power or offshore hydrogen pipelines). Offshore hydrogen pipelines are assessed as economical for large and distant farms. The decentralised offshore typology employing a semi-submersible platform could accommodate a proton exchange membrane electrolyser on deck; this would negate the need for an additional separate structure or hydrogen export compression and enhance dynamic operational ability. It is flexible; if one electrolyser (or turbine) fails hydrogen production can easily continue on the other turbines. It also facilities flexibility in further expansion as it is very much a modular system. Alternatively less complexity is associated with the centralised offshore typology which may employ the electrolysis facility on a separate offshore platform and be associated with a farm of spar-buoy platforms in significant water depth locations.
Hydrogen Production in the Swedish Power Sector: Considering Operational Volatilities and Long-term Uncertainties
Nov 2020
Publication
With more renewables on the Swedish electricity market while decommissioning nuclear power plants electricity supply increasingly fluctuates and electricity prices are more volatile. There is hence a need for securing the electricity supply before energy storage solutions become widespread. Electricity price fluctuations moreover affect operating income of nuclear power plants due to their inherent operational inflexibility. Since the anticipated new applications of hydrogen in fuel cell vehicles and steel production producing hydrogen has become a potential source of income particularly when there is a surplus supply of electricity at low prices. The feasibility of investing in hydrogen production was investigated in a nuclear power plant applying Swedish energy policy as background. The analysis applies a system dynamics approach incorporating the stochastic feature of electricity supply and prices. The study revealed that hydrogen production brings alternative opportunities for large-scale electricity production facilities in Sweden. Factors such as hydrogen price will be influential and require in-depth investigation. This study provides guidelines for power sector policymakers and managers who plan to engage in hydrogen production for industrial applications. Although this study was focused upon nuclear power sources it can be extended to hydrogen production from renewable energy sources such as wind and solar.
The Use of Strontium Ferrite in Chemical Looping Systems
May 2020
Publication
This work reports a detailed chemical looping investigation of strontium ferrite (SrFeO3−δ) a material with the perovskite structure type able to donate oxygen and stay in a nonstoichiometric form over a broad range of oxygen partial pressures starting at temperatures as low as 250°C (reduction in CO measured in TGA). SrFeO3−δ is an economically attractive simple but remarkably stable material that can withstand repeated phase transitions during redox cycling. Mechanical mixing and calcination of iron oxide and strontium carbonate was evaluated as an effective way to obtain pure SrFeO3−δ. In–situ XRD was performed to analyse structure transformations during reduction and reoxidation. Our work reports that much deeper reduction from SrFeO3−δ to SrO and Fe is reversible and results in oxygen release at a chemical potential suitable for hydrogen production. Thermogravimetric experiments with different gas compositions were applied to characterize the material and evaluate its available oxygen capacity. In both TGA and in-situ XRD experiments the material was reduced below δ=0.5 followed by reoxidation either with CO2 or air to study phase segregation and reversibility of crystal structure transitions. As revealed by in-situ XRD even deeply reduced material regenerates at 900°C to SrFeO3−δ with a cubic structure. To investigate the catalytic behaviour of SrFeO3−δ in methane combustion experiments were performed in a fluidized bed rig. These showed SrFeO3−δ donates O2 into the gas phase but also assists with CH4 combustion by supplying lattice oxygen. To test the material for combustion and hydrogen production long cycling experiments in a fluidized bed rig were also performed. SrFeO3−δ showed stability over 30 redox cycles both in experiments with a 2-step oxidation performed in CO2 followed by air as well as a single step oxidation in CO2 alone. Finally the influence of CO/CO2 mixtures on material performance was tested; a fast and deep reduction in elevated pCO2 makes the material susceptible to carbonation but the process can be reversed by increasing the temperature or lowering pCO2.
Computational Intelligence Approach for Modeling Hydrogen Production: A Review
Mar 2018
Publication
Hydrogen is a clean energy source with a relatively low pollution footprint. However hydrogen does not exist in nature as a separate element but only in compound forms. Hydrogen is produced through a process that dissociates it from its compounds. Several methods are used for hydrogen production which first of all differ in the energy used in this process. Investigating the viability and exact applicability of a method in a specific context requires accurate knowledge of the parameters involved in the method and the interaction between these parameters. This can be done using top-down models relying on complex mathematically driven equations. However with the raise of computational intelligence (CI) and machine learning techniques researchers in hydrology have increasingly been using these methods for this complex task and report promising results. The contribution of this study is to investigate the state of the art CI methods employed in hydrogen production and to identify the CI method(s) that perform better in the prediction assessment and optimization tasks related to different types of Hydrogen production methods. The resulting analysis provides in-depth insight into the different hydrogen production methods modeling technique and the obtained results from various scenarios integrating them within the framework of a common discussion and evaluation paper. The identified methods were benchmarked by a qualitative analysis of the accuracy of CI in modeling hydrogen production providing extensive overview of its usage to empower renewable energy utilization.
Seasonal Storage and Alternative Carriers: A Flexible Hydrogen Supply Chain Model
May 2017
Publication
A viable hydrogen infrastructure is one of the main challenges for fuel cells in mobile applications. Several studies have investigated the most cost-efficient hydrogen supply chain structure with a focus on hydrogen transportation. However supply chain models based on hydrogen produced by electrolysis require additional seasonal hydrogen storage capacity to close the gap between fluctuation in renewable generation from surplus electricity and fuelling station demand. To address this issue we developed a model that draws on and extends approaches in the literature with respect to long-term storage. Thus we analyse Liquid Organic Hydrogen Carriers (LOHC) and show their potential impact on future hydrogen mobility. We demonstrate that LOHC-based pathways are highly promising especially for smaller-scale hydrogen demand and if storage in salt caverns remains uncompetitive but emit more greenhouse gases (GHG) than other gaseous or hydrogen ones. Liquid hydrogen as a seasonal storage medium offers no advantage compared to LOHC or cavern storage since lower electricity prices for flexible operation cannot balance the investment costs of liquefaction plants. A well-to-wheel analysis indicates that all investigated pathways have less than 30% GHG-emissions compared to conventional fossil fuel pathways within a European framework.
Production Costs for Synthetic Methane in 2030 and 2050 of an Optimized Power-to-Gas Plant with Intermediate Hydrogen Storage
Aug 2019
Publication
The publication gives an overview of the production costs of synthetic methane in a Power-to-Gas process. The production costs depend in particularly on the electricity price and the full load hours of the plant sub-systems electrolysis and methanation. The full-load hours of electrolysis are given by the electricity supply concept. In order to increase the full-load hours of methanation the size of the intermediate hydrogen storage tank and the size of the methanation are optimised on the basis of the availability of hydrogen. The calculation of the production costs for synthetic methane are done with economics for 2030 and 2050 and the expenditures are calculated for one year of operation. The sources of volume of purchased electricity are the short-term market long-term contracts direct-coupled renewable energy sources or seasonal use of surpluses. Gas sales are either traded on the short-term market or guaranteed by long-term contracts. The calculations show that an intermediate storage tank for hydrogen adjustment of the methanation size and operating electrolysis and methanation separately increase the workload of the sub-system methanation. The gas production costs can be significantly reduced. With the future expected development of capital expenditures operational expenditure electricity prices gas costs and efficiencies an economic production of synthetic natural gas for the years 2030 especially for 2050 is feasible. The results show that Power-to-Gas is an option for long-term large-scale seasonal storage of renewable energy. Especially the cases with high operating hours for the sub-system methanation and low electricity prices show gas production costs below the expected market prices for synthetic gas and biogas.
Aqueous Phase Reforming of the Residual Waters Derived from Lignin-rich Hydrothermal Liquefaction: Investigation of Representative Organic Compounds and Actual Biorefinery Streams
Sep 2019
Publication
Secondary streams in biorefineries need to be valorized to improve the economic and environmental sustainability of the plants. Representative model compounds of the water fraction from the hydrothermal liquefaction (HTL) of biomass were subjected to aqueous phase reforming (APR) to produce hydrogen. Carboxylic and bicarboxylic acids hydroxyacids alcohols cycloketones and aromatics were identified as model compounds and tested for APR. The tests were performed with a Pt/C catalyst and the influence of the carbon concentration (0.3–1.8 wt. C%) was investigated. Typically the increase of the concentration negatively affected the conversion of the feed toward gaseous products without influencing the selectivity toward hydrogen production. A synthetic ternary mixture (glycolic acid acetic acid lactic acid) was subjected to APR to evaluate any differences in performance compared to the tests with single compounds. Indeed glycolic acid reacted faster in the mixture than in the corresponding single compound test while acetic acid remained almost unconverted. The influence of the reaction time temperature and carbon concentration was also evaluated. Finally residual water resulting from the HTL of a lignin-rich stream originating from an industrial-scale lignocellulosic ethanol process was tested for the first time after a thorough characterization. In this framework the stability of the catalyst was studied and found to be correlated to the presence of aromatics in the aqueous feedstock. For this reason the influence of an extraction procedure for the selective removal of these compounds was explored leading to an improvement in the APR performance.
Thermodynamic Assessment of the Novel Concept of the Energy Storage System Using Compressed Carbon Dioxide, Methanation and Hydrogen Generator
Jul 2021
Publication
The main aim of this paper is to characterize the concept of a novel energy storage system based on compressed CO2 storage installation that uses an infrastructure of depleted coal mines to provide required volume of tanks and additionally hydrogen generators and a methanation installation to generate synthetic natural gas that can be used within the system or taken out of it e.g. to a gas grid. A detailed mathematical model of the proposed solution was built using own codes and Aspen Plus software. Thermodynamic evaluation aiming at determining parameters composition and streams in all the most important nodes of the system for the nominal point and when changing a defined decision variable δ (in the range from 0.1 to 0.9) was made. The evaluation was made based on the storage efficiency volume of the tanks and flows of energy within the system. The storage efficiency in the nominal point reached 45.08% but was changing in the range from 35.06% (for δ = 0.1) to 63.93% (for δ = 0.9). For the nominal value of δ equal to 0.5 volume of the low-pressure tank (LPT) was equal to 132869 m3 while of the high pressure tank (HPT) to 1219 m3 . When changing δ these volumes were changing from 101900 m3 to 190878 m3 (for LPT) and from 935 to 1751 m3 (for HPT) respectively. Detailed results are presented in the paper and indicate high storage potential of the proposed solution in regions with underground mine infrastructure.
Hydrothermal Conversion of Lignin and Black Liquor for Phenolics with the Aids of Alkali and Hydrogen Donor
Jun 2019
Publication
The potentials of phenolic productions from lignin and black liquor (BL) via hydrothermal technology with the aids of alkalis and hydrogen donors were investigated by conducting batch experiments in micro-tube reactors with 300 °C sub-critical water as the solvent. The results showed that all the employed alkalis improved lignin degradation and thus phenolics production and the strong alkalis additionally manifested deoxygenation to produce more phenolics free of methoxyl group(s). Relatively hydrogen donors more visibly facilitated phenolics formation. Combination of strong alkali and hydrogen donors exhibited synergistically positive effects on producing phenolics (their total yield reaching 22 wt%) with high selectivities to phenolics among which the yields of catechol and cresols respectively peaked 16 and 3.5 wt%. BL could be hydrothermally converted into phenolics at high yields (approaching 10 wt% with the yields of catechol and cresols of about 4 and 2 wt% respectively) with the aids of its inherent alkali and hydrogen donors justifying its cascade utilization.
Transient Numerical Modeling and Model Predictive Control of an Industrial-scale Steam Methane Reforming Reactor
Mar 2021
Publication
A steam methane reforming reactor is a key equipment in hydrogen production and numerical analysis and process control can provide a critical insight into its reforming mechanisms and flexible operation in real engineering applications. The present paper firstly studies the transport phenomena in an industrial-scale steam methane reforming reactor by transient numerical simulations. Wall effect and local non thermal equilibrium is considered in the simulations. A temperature profile of the tube outer wall is given by user defined functions integrated into the ANSYS FLUENT software. Dynamic simulations show that the species distribution is closely related to the temperature distribution which makes the temperature of the reactor tube wall an important factor for the hydrogen production of the reformer and the thermal conductivity of the catalyst network is crucial in the heat transfer in the reactor. Besides there exists a delay of the reformer's hydrogen production when the temperature profile of the tube wall changes. Among inlet temperature inlet mass flow rate and inlet steam-to-carbon (S/C) ratio the mass flow rate is the most influencing factor for the hydrogen production. The dynamic matrix control (DMC) scheme is subsequently designed to manipulate the mole fraction of hydrogen of the outlet to the target value by setting the temperature profile trajectory of the reforming tube with time. The proportional-integral control strategy is also studied for comparison. The closed-loop simulation results show that the proposed DMC control strategy can reduce the overshoot and have a small change of the input variable. In addition the disturbances of feed disturbance can also be well rejected to assure the tracking performance indicating the superiority of the DMC controller. All the results give insight to the theoretical analysis and controller design of a steam methane reformer and demonstrate the potential of the CFD modeling in study the transport mechanism and the idea of combining CFD modelling with controller design for the real application.
Flexible Power & Biomass-to-Methanol Plants: Design Optimization and Economic Viability of the Electrolysis Integration
Nov 2021
Publication
This paper assesses the optimal design criteria of a flexible power and biomass to methanol (PBtM) plant conceived to operate both without green hydrogen addition (baseline mode) and with hydrogen addition (enhanced mode) following an intermittent use of the electrolysis system which is turned on when the electricity price allows an economically viable hydrogen production. The assessed plant includes a gasification section syngas cleaning and compression methanol synthesis and purification and heat recovery steam cycle to be flexibly operated. A sorption-enhanced gasification technology allows to produce a tailored syngas for the downstream synthesis in both the baseline and enhanced operating conditions by controlling the in-situ CO2 separation rate. Two designs are assessed for the methanol synthesis unit with two different reactor sizes: (i) a larger reactor designed on the enhanced operation mode (enhanced reactor design – ERD) and (ii) a smaller reactor designed on the baseline operation mode (baseline reactor design – BRD). The ERD design resulted to be preferable from the techno economic perspectives resulting in 20% lower cost of the e-MeOH (30.80 vs. 37.76 €/ GJLHV) with the baseline assumptions (i.e. 80% of electrolyzer capacity factor and 2019 Denmark day-ahead market electricity price). Other important outcomes are: (i) high electrolysis capacity factor is needed to obtain competitive cost of e-MeOH and (ii) advantages of flexibly operated PBtM plants with respect to inflexible PBtM plants are significant in scenarios with high penetration of intermittent renewables leading to low average prices of electricity but also longer periods of high peak prices.
True Cost of Solar Hydrogen
Sep 2021
Publication
Green hydrogen will be an essential part of the future 100% sustainable energy and industry system. Up to one-third of the required solar and wind electricity would eventually be used for water electrolysis to produce hydrogen increasing the cumulative electrolyzer capacity to about 17 TWel by 2050. The key method applied in this research is a learning curve approach for the key technologies i.e. solar photovoltaics (PV) and water electrolyzers and levelized cost of hydrogen (LCOH). Sensitivities for the hydrogen demand and various input parameters are considered. Electrolyzer capital expenditure (CAPEX) for a large utility-scale system is expected to decrease from the current 400 €/kWel to 240 €/kWel by 2030 and to 80 €/kWel by 2050. With the continuing solar PV cost decrease this will lead to an LCOH decrease from the current 31–81 €/ MWhH2LHV (1.0–2.7 €/kgH2) to 20–54 €/MWhH2LHV (0.7–1.8 €/kgH2) by 2030 and 10–27 €/MWhH2LHV (0.3–0.9 €/kgH2) by 2050 depending on the location. The share of PV electricity cost in the LCOH will increase from the current 63% to 74% by 2050.
HydroGenerally - Episode 1: The Colours of Hydrogen
Mar 2022
Publication
This first episode was inspired by an Innovate UK KTN perspective commenting on the UK government’s Hydrogen Strategy released by the Department of Business Energy and Industrial Strategy (BEIS) in August 2021. Following the publication of this perspective it was very evident to our Innovate UK KTN experts that the uses and challenges of ‘blue’ and ‘green’ hydrogens were generating a strong debate depending on their application areas.
Over a 20-minute discussion Simon Steffan and Sam try to answer the questions: how is hydrogen currently produced? How will it be produced in the future? And how will it fit in with the energy system?
The podcast can be found on their website
Over a 20-minute discussion Simon Steffan and Sam try to answer the questions: how is hydrogen currently produced? How will it be produced in the future? And how will it fit in with the energy system?
The podcast can be found on their website
Hydrogen Production from the Air
Sep 2022
Publication
Green hydrogen produced by water splitting using renewable energy is the most promising energy carrier of the low-carbon economy. However the geographic mismatch between renewables distribution and freshwater availability poses a significant challenge to its production. Here we demonstrate a method of direct hydrogen production from the air namely in situ capture of freshwater from the atmosphere using hygroscopic electrolyte and electrolysis powered by solar or wind with a current density up to 574 mA cm−2 . A prototype of such has been established and operated for 12 consecutive days with a stable performance at a Faradaic efficiency around 95%. This so-called direct air electrolysis (DAE) module can work under a bone-dry environment with a relative humidity of 4% overcoming water supply issues and producing green hydrogen sustainably with minimal impact to the environment. The DAE modules can be easily scaled to provide hydrogen to remote (semi-) arid and scattered areas.
Energy Efficiency Based Control Strategy of a Three-Level Interleaved DC-DC Buck Converter Supplying a Proton Exchange Membrane Electrolyzer
Aug 2019
Publication
To face the intensive use of natural gas and other fossil fuels to generate hydrogen water electrolysis based on renewable energy sources (RES) seems to be a viable solution. Due to their fast response times and high efficiency proton exchange membrane electrolyzer (PEM EL) is the most suitable technology for long-term energy storage combined with RES. Like fuel cells the development of fit DC-DC converters is mandatory to interface the EL to the DC grid. Given that PEM EL operating voltages are quite low and to meet requirements in terms of output current ripples new emerging interleaved DC-DC converter topologies seem to be the best candidates. In this work a three-level interleaved DC-DC buck converter has been chosen to supply a PEM EL from a DC grid. Therefore the main objective of this paper is to develop a suitable control strategy of this interleaved topology connected to a PEM EL emulator. To design the control strategy investigations have been carried out on energy efficiency hydrogen flow rate and specific energy consumption. The obtained experimental results validate the performance of the converter in protecting the PEM EL during transient operations while guaranteeing correct specific energy consumption.
Cow Dung Gasification Process for Hydrogen Production Using Water Vapor as Gasification Agent
Jun 2022
Publication
In recent years with the development of hydrogen energy economy there is an increasing demand for hydrogen in the market and hydrogen production through biomass will provide an important way to supply clean environmentally friendly and highly efficient hydrogen. In this study cow dung was selected as the biomass source and the efficiency of the biomass to hydrogen reaction was explored by coupling high temperature pyrolysis and water vapor gasification. The experimental conditions of gasification temperature water mass fraction heating rate and feed temperature were systematically studied and optimized to determine the optimal conditions for in situ hydrogen production by gasification of cow dung. The relationship of each factor to the yield of hydrogen production by gasification of cow dung semi-coke was investigated in order to elucidate the mechanism of the hydrogen production. The experiment determined the optimal operating parameters of in situ gasification: gasification temperature 1173 K water mass fraction 80% heating rate 10 K/min and feed temperature 673 K. The semi-coke treatment separated high temperature pyrolysis and water vapor gasification and reduced the influence on gasification of volatile substances such as tar extracted from pyrolysis. The increase of semi-coke preparation temperature increases the content of coke reduces the volatile matter and improves the yield of hydrogen; the small size of semi-coke particles and large specific surface area are beneficial to the gasification reaction.
Electrofuels from Excess Renewable Electricity at High Variable Renewable Shares: Cost, Greenhouse Gas Abatement, Carbon Use and Competition
Nov 2020
Publication
Increasing shares of variable renewable electricity (VRE) generation are necessary for achieving high renewable shares in all energy sectors. This results in increased excess renewable electricity (ERE) at times when supply exceeds demand. ERE can be utilized as a low-emission energy source for sector coupling through hydrogen production via electrolysis which can be used directly or combined with a carbon source to produce electrofuels. Such fuels are crucial for the transport sector where renewable alternatives are scarce. However while ERE increases with raising VRE shares carbon emissions decrease and may become a limited resource with several usage options including carbon storage (CCS). Here we perform a model based analysis for the German case until 2050 with a general analysis for regions with a high VRE reliance. Results indicate that ERE-based electrofuels could achieve a greenhouse gas (GHG) abatement of 74 MtCO2eq yearly (46% of current German transport emissions) by displacing fossil fuels at high fuel-cell electric vehicle (FCEV) shares at a cost of 250–320 V per tCO2eq. The capital expenditure of electrolysers was found not to be crucial for the cost despite low capacity factors due to variable ERE patterns. Carbon will likely become a limiting factor when aiming for stringent climate targets and renewable electricity-based hydrocarbon electrofuels replacing fossil fuels achieve up to 70% more GHG abatement than CCS. Given (1) an unsaturated demand for renewable hydrocarbon fuels (2) a saturated renewable hydrogen demand and (3) unused ERE capacities which would otherwise be curtailed we find that carbon is better used for renewable fuel production than being stored in terms of overall GHG abatement.
Green Hydrogen Production by Anion Exchange Membrane Water Electrolysis: Status and Future Perspectives
Jan 2023
Publication
Green hydrogen production i.e. produced on a CO2 -neutral basis through the electrolysis of water employing renewable electricity has attracted increasing attention. The electricity required is generated from Renewable Energy Sources (RES) for example wind energy hydropower or solar energy. Since neither the process of production nor the end products of H2 and O2 are harmful to the environment green hydrogen is climate neutral. Developing electrolysis technology is therefore a research topic to follow. Anion Exchange Membrane (AEM) Water Electrolysis (WE) is an innovative technology that couples the advantages of the more mature technologies of Proton Exchange Membrane (PEM) and conventional alkaline electrolysis with the potential to eliminate the drawbacks of both. AEMWE technology is in an evolutionary stage and involves more investigation on several research topics such as membrane and catalyst development and stability as well as alternative feeding solutions that do not compromise the availability of fresh water. These topics are addressed in this paper mentioning the state-of-the-art materials new promising ones and providing future research directions to improve AEMWE towards a most mature technology.
Graphene Oxide @ Nickel Phosphate Nanocomposites for Photocatalytic Hydrogen Production
Mar 2021
Publication
The graphene oxide @nickel phosphate (GO:NPO) nanocomposites (NCs) are prepared by using a one-pot in-situ solar energy assisted method by varying GO:NPO ratio i.e. 0.00 0.25 0.50 0.75 1.00 1.25 1.50 and 2.00 without adding any surfactant or a structure-directing reagent. As produced GO:NPO nanosheets exhibited an improved photocatalytic activity due to the spatial seperation of charge carriers through interface where photoinduced electrons transferred from NiPO4 to the GO sheets without charge-recombination. Out of the series the system 1.00 GO:NPO NC show the optimum hydrogen production activity (15.37 μmol H2 h−1) towards water splitting under the visible light irradiation. The electronic environment of the nanocomposite GO-NiO6/NiO4-PO4 elucidated in the light of advance experimental analyses and theoretical DFT spin density calculations. Structural advanmcement of composites are well correlated with their hydrogen production activity.
The Route from Green H2 Production through Bioethanol Reforming to CO2 Catalytic Conversion: A Review
Mar 2022
Publication
Currently a progressively different approach to the generation of power and the production of fuels for the automotive sector as well as for domestic applications is being taken. As a result research on the feasibility of applying renewable energy sources to the present energy scenario has been progressively growing aiming to reduce greenhouse gas emissions. Following more than one approach the integration of renewables mainly involves the utilization of biomass-derived raw material and the combination of power generated via clean sources with conventional power generation systems. The aim of this review article is to provide a satisfactory overview of the most recent progress in the catalysis of hydrogen production through sustainable reforming and CO2 utilization. In particular attention is focused on the route that starting from bioethanol reforming for H2 production leads to the use of the produced CO2 for different purposes and by means of different catalytic processes passing through the water–gas shift stage. The newest approaches reported in the literature are reviewed showing that it is possible to successfully produce “green” and sustainable hydrogen which can represent a power storage technology and its utilization is a strategy for the integration of renewables into the power generation scenario. Moreover this hydrogen may be used for CO2 catalytic conversion to hydrocarbons thus giving CO2 added value.
A Review of the Use of Electrolytic Cells for Energy and Environmental Applications
Feb 2023
Publication
There is a significant push to reduce carbon dioxide (CO2) emissions and develop low-cost fuels from renewable sources to replace fossil fuels in applications such as energy production. As a result CO2 conversion has gained widespread attention as it can reduce the accumulation of CO2 in the atmosphere and produce fuels and valuable industrial chemicals including carbon monoxide alcohols and hydrocarbons. At the same time finding ways to store energy in batteries or energy carriers such as hydrogen (H2) is essential. Water electrolysis is a powerful technology for producing high-purity H2 with negligible emission of greenhouse gases and compatibility with renewable energy sources. Additionally the electrolysis of organic compounds such as lignin is a promising method for localised H2 production as it requires lower cell voltages than conventional water electrolysis. Industrial wastewater can be employed in those organic electrolysis systems due to their high organic content decreasing industrial pollution through wastewater disposal. Electrocoagulation indirect electrochemical oxidation anodic oxidation and electro-Fenton are effective electrochemical methods for treating industrial wastewater. Furthermore bioenergy technology possesses a remarkable potential for producing H2 and other value-added chemicals (e.g. methane formic acid hydrogen peroxide) along with wastewater treatment. This paper comprehensively reviews these approaches by analysing the literature in the period 2012–2022 pointing out the high potential of using electrolytic cells for energy and environmental applications.
Green Energy by Hydrogen Production from Water Splitting, Water Oxidation Catalysis and Acceptorless Dehydrogenative Coupling
Feb 2023
Publication
In this review we want to explain how the burning of fossil fuels is pushing us towards green energy. Actually for a long time we have believed that everything is profitable that resources are unlimited and there are no consequences. However the reality is often disappointing. The use of non-renewable resources the excessive waste production and the abandonment of the task of recycling has created a fragile thread that once broken may never restore itself. Metaphors aside we are talking about our planet the Earth and its unique ability to host life including ourselves. Our world has its balance; when the wind erodes a mountain a beach appears or when a fire devastates an area eventually new life emerges from the ashes. However humans have been distorting this balance for decades. Our evolving way of living has increased the number of resources that each person consumes whether food shelter or energy; we have overworked everything to exhaustion. Scientists worldwide have already said actively and passively that we are facing one of the biggest problems ever: climate change. This is unsustainable and we must try to revert it or if we are too late slow it down as much as possible. To make this happen there are many possible methods. In this review we investigate catalysts for using water as an energy source or instead of water alcohols. On the other hand the recycling of gases such as CO2 and N2O is also addressed but we also observe non-catalytic means of generating energy through solar cell production.
Time-phased Geospatial Siting Analysis for Renewable Hydrogen Production Facilities under a Billion-kilogram-scale Build-out using California as an Example
Jun 2022
Publication
For renewable hydrogen to be a significant part of the future decarbonized energy and transportation sectors a rapid and massive build-out of hydrogen production facilities will be needed. This paper describes a geospatial modeling approach to identifying the optimal locations for renewable hydrogen fuel production throughout the state of California based on least-cost generation and transport. This is accomplished by (1) estimating and projecting California renewable hydrogen demand scenarios through the year 2050 (2) identifying feedstock locations (3) excluding areas not suitable for development and (4) selecting optimal site locations using commercial geospatial modeling software. The findings indicate that there is a need for hundreds of new renewable hydrogen production facilities in the decades preceding the year 2050. In selecting sites for development feedstock availability by technology type is the driving factor."
Machine Learning-based Energy Optimization for On-site SMR Hydrogen Production
Jun 2021
Publication
The production and application of hydrogen an environmentally friendly energy source have been attracting increasing interest of late. Although steam methane reforming (SMR) method is used to produce hydrogen it is difficult to build a high-fidelity model because the existing equation-oriented theoretical model cannot be used to clearly understand the heat-transfer phenomenon of a complicated reforming reactor. Herein we developed an artificial neural network (ANN)-based data-driven model using 485710 actual operation datasets for optimizing the SMR process. Data preprocessing including outlier removal and noise filtering was performed to improve the data quality. A model with high accuracy (average R2 = 0.9987) was developed which can predict six variables through hyperparameter tuning of a neural network model as follows: syngas flow rate; CO CO2 CH4 and H2 compositions; and steam temperature. During optimization the search spaces for nine operating variables namely the natural gas flow rate for the feed and fuel hydrogen flow rate for desulfurization water flow rate and temperature air flow rate SMR inlet temperature and pressure and low-temperature shift (LTS) inlet temperature were defined and applied to the developed model for predicting the thermal efficiencies for 387420489 cases. Subsequently five constraints were established to consider the feasibility of the process and the decision variables with the highest process thermal efficiency were determined. The process operating conditions showed a thermal efficiency of 85.6%.
Modeling of a High Temperature Heat Exchanger to Supply Hydrogen Required by Fuel Cells Through Reforming Process
Sep 2021
Publication
Hydrogen as a clean fuel and a new energy source can be produced by various methods. One of these common and economical methods of hydrogen production is hydrocarbon vapor modification. This research studies hydrogen production using a propane steam reforming process inside a high temperature heat exchanger. The application of this high temperature heat exchanger in the path of the power supply line is a fuel cell stack unit to supply the required hydrogen of the device. The heat exchanger consists of a set of cylindrical tubes housed inside a packed-bed called a reformer. The energy required to perform the reaction is supplied through these tubes in which high temperature gas is injected and the heat exchanger is insulated to prevent energy loss. The results show that at maximum temperature and velocity of hot gases (900 K and 1.5 m s−1 ) complete consumption of propane can be observed before the outlet of the reformer. Also in the mentioned conditions the maximum hydrogen production (above 92%) is obtained. The best permeability under which the system can perform best is 1×10−9 m2.
Hydrogen Production from Surplus Electricity Generated by an Autonomous Renewable System: Scenario 2040 on Grand Canary Island, Spain
Sep 2022
Publication
The electrification of final energy uses is a key strategy to reach the desired scenario with zero greenhouse gas emissions. Many of them can be electrified with more or less difficulty but there is a part that is difficult to electrify at a competitive cost: heavy road transport maritime and air transport and some industrial processes are some examples. For this reason the possibility of using other energy vectors rather than electricity should be explored. Hydrogen can be considered a real alternative especially considering that this transition should not be carried out immediately because initially the electrification would be carried out in those energy uses that are considered most feasible for this conversion. The Canary Islands’ government is making considerable efforts to promote a carbon-free energy mix starting with renewable energy for electricity generation. Still in the early–mid 2030s it will be necessary to substitute heavy transport fossil fuel. For this purpose HOMER software was used to analyze the feasibility of hydrogen production using surplus electricity produced by the future electricity system. The results of previous research on the optimal generation MIX for Grand Canary Island based exclusively on renewable sources were used. This previous research considers three possible scenarios where electricity surplus is in the range of 2.3–4.9 TWh/year. Several optimized scenarios using demand-side management techniques were also studied. Therefore based on the electricity surpluses of these scenarios the optimization of hydrogen production and storage systems was carried out always covering at least the final hydrogen demand of the island. As a result it is concluded that it would be possible to produce 3.5 × 104 to 7.68 × 104 t of H2/year. In these scenarios 3.15 × 105 to 6.91 × 105 t of water per year would be required and there could be a potential production of 2.8 × 105 to 6.14 × 105 t of O2 per year.
Roadmap to Hybrid Offshore System with Hydrogen and Power Co-generation
Sep 2021
Publication
Constrained by the expansion of the power grid the development of offshore wind farms may be hindered and begin to experience severe curtailment or restriction. The combination of hydrogen production through electrolysis and hydrogen-to-power is considered to be a potential option to achieve the goal of low-carbon and energy security. This work investigates the competitiveness of different system configurations to export hydrogen and/or electricity from offshore plants with particular emphasis on unloading the mixture of hydrogen and electricity to end-users on land. Including the levelized energy cost and net present value a comprehensive techno-economic assessment method is proposed to analyze the offshore system for five scenarios. Assuming that the baseline distance is 10 km the results show that exporting hydrogen to land through pipelines shows the best economic performance with the levelized energy cost of 3.40 $/kg. For every 10 km increase in offshore distance the net present value of the project will be reduced by 5.69 MU$ and the project benefit will be positive only when the offshore distance is less than 53.5 km. An important finding is that the hybrid system under ship transportation mode is not greatly affected by the offshore distance. Every 10% increase in the proportion of hydrogen in the range of 70%–100% can increase the net present value by 1.43–1.70 MU$ which will increase by 7.36–7.37 MU$ under pipeline transportation mode. Finally a sensitivity analysis was carried out to analyze the wind speed electricity and hydrogen prices on the economic performance of these systems.
The Impact of Operating Conditions on the Performance of a CH4 Dry Reforming Membrane Reactor for H2 Production
May 2020
Publication
Biogas is a promising resource for the production of H2 since it liberates energy by recycling waste along with the reduction of CO2. In this paper the biogas dry reforming membrane reactor is proposed to produce H2 for use in fuel cells. Pd/Cu alloy membrane is used to enhance the performance of the biogas dry reforming reactor. This study aims at understanding the effect of operating parameters such as feed ratio of sweep gas pressure in the reactor and reaction temperature on the performance of the biogas dry reforming membrane reactor. The effect of the molar ratio of the supplied CH4:CO2 feed ratio of the sweep gas and the valve located at the outlet of the reaction chamber on the performance of biogas dry reforming are investigated. Besides the thermal efficiency of the proposed reactor is also evaluated. The results show that the concentration of H2 in the closed valve condition is higher than that of the open valve and the optimum feed ratio of the sweep gas to produce H2 is 1 irrespective of the molar ratio of supplied CH4:CO2. Also H2 selectivity and CO selectivity increases and decreases respectively when the reaction temperature increases irrespective of the molar ratio of supplied CH4:CO2. Therefore the thermal efficiency of the closed valve is higher than that of the opened valve. Also the thermal efficiency is the maximum when the feed ratio of the sweep gas is 1 due to high H2 production performance.
An Investigation of a (Vinylbenzyl) Trimethylammonium and N-Vinylimidazole-Substituted Poly (Vinylidene Fluoride-Co-Hexafluoropropylene) Copolymer as an Anion-Exchange Membrane in a Lignin-Oxidising Electrolyser
Jun 2021
Publication
Electrolysis is seen as a promising route for the production of hydrogen from water as part of a move to a wider “hydrogen economy”. The electro-oxidation of renewable feedstocks offers an alternative anode couple to the (high-overpotential) electrochemical oxygen evolution reaction for developing low-voltage electrolysers. Meanwhile the exploration of new membrane materials is also important in order to try and reduce the capital costs of electrolysers. In this work we synthesise and characterise a previously unreported anion-exchange membrane consisting of a fluorinated polymer backbone grafted with imidazole and trimethylammonium units as the ion-conducting moieties. We then investigate the use of this membrane in a lignin-oxidising electrolyser. The new membrane performs comparably to a commercially-available anion-exchange membrane (Fumapem) for this purpose over short timescales (delivering current densities of 4.4 mA cm−2 for lignin oxidation at a cell potential of 1.2 V at 70 °C during linear sweep voltammetry) but membrane durability was found to be a significant issue over extended testing durations. This work therefore suggests that membranes of the sort described herein might be usefully employed for lignin electrolysis applications if their robustness can be improved.
Selected Aspects of Hydrogen Production via Catalytic Decomposition of Hydrocarbons
Feb 2021
Publication
Owing to the high hydrogen content hydrocarbons are considered as an alternative source for hydrogen energy purposes. Complete decomposition of hydrocarbons results in the formation of gaseous hydrogen and solid carbonaceous by-product. The process is complicated by the methane formation reaction when the released hydrogen interacts with the formed carbon deposits. The present study is focused on the effects of the reaction mixture composition. Variations in the inlet hydrogen and methane concentrations were found to influence the carbon product’s morphology and the hydrogen production efficiency. The catalyst containing NiO (82 wt%) CuO (13 wt%) and Al2O3 (5 wt%) was prepared via a mechanochemical activating procedure. Kinetics of the catalytic process of hydrocarbons decomposition was studied using a reactor equipped with McBain balances. The effects of the process parameters were explored in a tubular quartz reactor with chromatographic analysis of the outlet gaseous products. In the latter case the catalyst was loaded piecemeal. The texture and morphology of the produced carbon deposits were investigated by nitrogen adsorption and electron microscopy techniques.
How Do Dissolved Gases Affect the Sonochemical Process of Hydrogen Production: An Overview of Thermodynamic and Mechanistic Effects – On the “Hot Spot Theory”
Dec 2020
Publication
Although most of researchers agree on the elementary reactions behind the sonolytic formation of molecular hydrogen (H2) from water namely the radical attack of H2O and H2O2 and the free radicals recombination several recent papers ignore the intervention of the dissolved gas molecules in the kinetic pathways of free radicals and hence may wrongly assess the effect of dissolved gases on the sonochemical production of hydrogen. One may fairly ask to which extent is it acceptable to ignore the role of the dissolved gas and its eventual decomposition inside the acoustic cavitation bubble? The present opinion paper discusses numerically the ways in which the nature of dissolved gas i.e. N2 O2 Ar and air may influence the kinetics of sonochemical hydrogen formation. The model evaluates the extent of direct physical effects i.e. dynamics of bubble oscillation and collapse events if any against indirect chemical effects i.e. the chemical reactions of free radicals formation and consequently hydrogen emergence it demonstrates the improvement in the sonochemical hydrogen production under argon and sheds light on several misinterpretations reported in earlier works due to wrong assumptions mainly related to initial conditions. The paper also highlights the role of dissolved gases in the nature of created cavitation and hence the eventual bubble population phenomena that may prevent the achievement of the sonochemical activity. This is particularly demonstrated experimentally using a 20 kHz Sinaptec transducer and a Photron SA 5 high speed camera in the case of CO2-saturated water where degassing bubbles are formed instead of transient cavitation.
Suitable Site Selection for Solar‐Based Green Hydrogen in Southern Thailand Using GIS‐MCDM Approach
May 2022
Publication
Climate change mitigation efforts are in dire need of greener and more versatile fuel al‐ ternatives to fossil fuels. Green hydrogen being both renewable and flexible has the potential to offset fossil fuels as the primary fuel source. Countries around the world are planning to develop their green hydrogen industries and accurate potential assessment is vital. This study employed the consolidation of a geographic information system (GIS) and the analytical hierarchy process (AHP) technique of multicriteria decision making (MCDM) for the potential assessment of green hydrogen in southern Thailand through the selection of suitable sites for solar‐based green hy‐ drogen production. Technical economic and environmental criteria with 10 sub‐criteria were con‐ sidered for the selection of suitable sites. With 0.243 (24.3%) weight the distance from protected areas turned out to be the most important sub‐criterion whereas the criterion of elevation with a 0.017 (1.7%) score was considered the least important. Southern Thailand is a well‐suited area for solar‐based green hydrogen production with a 4302 km2 area of high suitability and a 3350 km2 area of moderate suitability. These suitable areas can be utilized to develop the green hydrogen industry of Thailand and the method developed can be employed for the assessment of green hydrogen potential in other parts of the country. Studies like these are vital for the development of green hydrogen road maps for Thailand to develop its hydrogen policy and promote investments in the sector.
Water Photo-Oxidation Reaction on Clean and Doped Two-Dimensional Graphitic C2N
Apr 2020
Publication
In the search for new efficient photo-catalysts for hydrogen production through water splitting the main attention has been paid to tuning the band gap width and its position with respect to vacuum level. However actual electro-catalytic activity for the water oxidation reaction on a catalyst surface is no less important than those quantities. In this work we evaluate from first principles the thermodynamics of the reaction on relatively new candidates for water splitting: two-dimensional C2N and that doped with phosphorus. We find that the 4-step reaction usually expected for water splitting will not proceed on these systems resulting in oxygen atoms left strongly adsorbed to the surface. Another option a 3-step reaction is also found to be unfavorable. We also test an effect of higher oxygen coverage on the reaction thermodynamics as suggested elsewhere. We find that indeed the doubled O-coverage makes the 4-step reaction feasible for the doped C2N. However an unacceptably high anode potential is required to make this reaction proceed. We thus conclude that the materials under consideration may not be efficient electro-catalysts for water splitting.
Life Cycle Assessment of Hydrogen from Proton Exchange Membrane Water Electrolysis in Future Energy Systems
Jan 2019
Publication
This study discusses the potential of H2 production by proton exchange membrane water electrolysis as an effective option to reduce greenhouse gas emissions in the hydrogen sector. To address this topic a life cycle assessment is conducted to compare proton exchange membrane water electrolysis versus the reference process - steam methane reforming. As a relevant result we show that hydrogen production via proton exchange membrane water electrolysis is a promising technology to reduce CO2 emissions of the hydrogen sector by up to 75% if the electrolysis system runs exclusively on electricity generated from renewable energy sources. In a future (2050) base-load operation mode emissions are comparable to the reference system.
The results for the global warming potential show a strong reduction of greenhouse gas emissions by 2050. The thoroughly and in-depth modelled components of the electrolyser have negligible influence on impact categories; thus emissions are mainly determined by the electricity mix. With 2017 electricity mix of Germany the global warming potential corresponds to 29.5 kg CO2 eq. for each kg of produced hydrogen. Referring to the electricity mix we received from an energy model emissions can be reduced to 11.5 kg CO2 eq. in base-load operation by the year 2050. Using only the 3000 h of excess power from renewables in a year will allow for the reduction of the global warming potential to 3.3 kg CO2 eq. From this result we see that an environmentally friendly electricity mix is crucial for reducing the global warming impact of electrolytic hydrogen.
The results for the global warming potential show a strong reduction of greenhouse gas emissions by 2050. The thoroughly and in-depth modelled components of the electrolyser have negligible influence on impact categories; thus emissions are mainly determined by the electricity mix. With 2017 electricity mix of Germany the global warming potential corresponds to 29.5 kg CO2 eq. for each kg of produced hydrogen. Referring to the electricity mix we received from an energy model emissions can be reduced to 11.5 kg CO2 eq. in base-load operation by the year 2050. Using only the 3000 h of excess power from renewables in a year will allow for the reduction of the global warming potential to 3.3 kg CO2 eq. From this result we see that an environmentally friendly electricity mix is crucial for reducing the global warming impact of electrolytic hydrogen.
EU Hydrogen Strategy: A Case for Urgent Action Towards Implementation
Jul 2020
Publication
Interest in hydrogen as one route to the decarbonisation of energy systems has risen rapidly over the past few years with the publication of a number of hydrogen strategies from countries across the global energy economy. The momentum in Europe has increased sharply this month with the publication of an EU strategy to incorporate hydrogen into its plans for a net zero emission future. This Comment reviews the key elements of this strategy and provides an initial commentary on the main goals. We highlight the challenges that will be faced in meeting hydrogen production targets in particular via the “green hydrogen” route and analyse the plans for expanding the consumption of hydrogen in Europe. We also assess the infrastructure questions that will need to be answered if and when hydrogen takes on a greater role in the region and note the extensive state support that will be needed in the early years of the implementation of the strategy. Despite this though we applaud the ambition laid out by the EU and look forward to the provision of more detailed plans over the coming months and years.
Link to document on OIES website
Link to document on OIES website
Current Legislative Framework for Green Hydrogen Production by Electrolysis Plants in Germany
Mar 2022
Publication
(1) The German energy system transformation towards an entirely renewable supply is expected to incorporate the extensive use of green hydrogen. This carbon-free fuel allows the decarbonization of end-use sectors such as industrial high-temperature processes or heavy-duty transport that remain challenging to be covered by green electricity only. However it remains unclear whether the current legislative framework supports green hydrogen production or is an obstacle to its rollout. (2) This work analyzes the relevant laws and ordinances regarding their implications on potential hydrogen production plant operators. (3) Due to unbundling-related constraints potential operators from the group of electricity transport system and distribution system operators face lacking permission to operate production plants. Moreover ownership remains forbidden for them. The same applies to natural gas transport system operators. The case is less clear for natural gas distribution system operators where explicit regulation is missing. (4) It is finally analyzed if the production of green hydrogen is currently supported in competition with fossil hydrogen production not only by the legal framework but also by the National Hydrogen Strategy and the Amendment of the Renewable Energies Act. It can be concluded that in recent amendments of German energy legislation regulatory support for green hydrogen in Germany was found. The latest legislation has clarified crucial points concerning the ownership and operation of electrolyzers and the treatment of green hydrogen as a renewable energy carrier.
Numerical Study on Optics and Heat Transfer of Solar Reactor for Methane Thermal Decomposition
Oct 2021
Publication
This study aims to reduce greenhouse gas emissions to the atmosphere and effectively utilize wasted resources by converting methane the main component of biogas into hydrogen. Therefore a reactor was developed to decompose methane into carbon and hydrogen using solar thermal sources instead of traditional energy sources such as coal and petroleum. The optical distributions were analyzed using TracePro a Monte Carlo ray-tracing-based program. In addition Fluent a computational fluid dynamics program was used for the heat and mass transfer and chemical reaction. The cylindrical indirect heating reactor rotates at a constant speed to prevent damage by the heat source concentrated at the solar furnace. The inside of the reactor was filled with a porous catalyst for methane decomposition and the outside was surrounded by insulation to reduce heat loss. The performance of the reactor according to the cavity model was calculated when solar heat was concentrated on the reactor surface and methane was supplied into the reactor in an environment with a solar irradiance of 700 W/m2 wind speed of 1 m/s and outdoor temperature of 25 °C. As a result temperature methane mass fraction distribution and heat loss amounts for the two cavities were obtained and it was found that the effect on the conversion rate was largely dependent on a temperature over 1000 °C in the reactor. Moreover the heat loss of the full-cavity model decreased by 12.5% and the methane conversion rate increased by 33.5% compared to the semi-cavity model. In conclusion the high-temperature environment of the reactor has a significant effect on the increase in conversion rate with an additional effect of reducing heat loss.
The Hydrogen Grand Challenge
Apr 2016
Publication
More than 90% of the world’s growing energy demand is satisfied by fossil fuels (BP Statistical Review … 2015)1. One consequence of the unrestrained use of this technology is the continuous increase of the CO2 level of the atmosphere2. There are also the challenges associated with the limitations of the corresponding resources (Hubbert 1956; BP Statistical Review … 2015). Climate change as a consequence of the growing CO2 level (see text footnote 2 ESRL Global Monitoring Division 2015) has been identified as one of the most critical challenges facing mankind and requires immediate action: “The Paris Agreement aims to strengthen the global response to the threat of climate change ( … ) by low greenhouse gas emissions development in a manner that does not threaten food production” (United Nations Framework … 2015). How to reach the corresponding significant reduction of CO2 emission by 2050 is not defined in this document but it implies that mankind must transform its energy technology from a fossil to a renewable basis. Numerous studies and publications have indicated that the sun’s energy and its derivatives (wind water) are by far sufficient to supply world’s energy demand (see e.g. Smalley 2005; Züttel et al. 2010); but the large daily and seasonal power variation of renewable energy is an additional complication for a wide spread replacement of fossil energy by renewable energy.
Analysis of Standard and Innovative Methods for Allocating Upstream and Refinery GHG Emissions to Oil Products
Sep 2017
Publication
Alternative fuel policies need accurate and transparent methods to find the embedded carbon intensity of individual refinery products. This study investigates different ways of allocating greenhouse gases emissions deriving from refining and upstream crude oil supply. Allocation methods based on mass energy content economic value and innovatively added-value are compared with the marginal refining emissions calculated by CONCAWE’s linear-programming model to the average EU refinery which has been adopted as reference in EU legislation. Beside the most important transportation fuels (gasoline diesel kerosene/jet fuel and heavy fuel oil) the analysis extends to petroleum coke and refinery hydrogen. Moreover novel criteria based on the implications due to hydrogen usage by each fuel pathway have been introduced to test the consistency of the analyzed approaches. It is found that only two economic-based allocation methods are consistent with the introduced criteria. These two methods also give negative refinery emissions for heavy products which is coherent with the marginal emissions calculated through the CONCAWE refinery model. The recommended allocation methods are transparent and use only publicly available statistical data so they may be useful not only for future EU legislation but also in jurisdictions where a representative refinery model is not available.
Design and Multi-scenario Optimization of a Hybrid Power System Based on a Working Gas Turbine: Energy, Exergy, Exergoeconomic and Environmental Evaluation
Sep 2022
Publication
The rising demand for electricity along with the need to minimize carbon footprints has motivated academics to investigate the flexible and efficient integration of energy conversion technologies. A novel hybrid power generation system based on environmentally friendly and cost-effective technologies to recover the waste heat of a working gas turbine is designed and assessed in different scenarios of multi-objective optimization from energy exergy exergoeconomic and environmental (4E) perspectives. In the proposed system a steam methane reformer and a water gas shift reactor are utilized for hydrogen production while a polymer electrolyte membrane fuel cell (PEMFC) and steam/organic Rankine cycles are run for generating additional power. Aspen Plus in conjunction with Fortran Microsoft Excel and MATLAB is used to model and simulate the designed plant. The response surface methodology (RSM) is utilized to determine accurate surrogate models to describe the evaluation criteria and the Non-dominated Sorting Genetic Algorithm II technique is employed to seek the optimal conditions. Moreover TOPSIS and LINMAP decision-making approaches are used to find the best final solution among Pareto frontiers. The analysis of variance (ANOVA) and sensitivity analysis are also applied to evaluate the importance of the design variables. In this regard three single-objective optimizations and four multi-objective optimization scenarios based on the maximization of the ecological coefficient of performance (ECOP) and the minimization of CO2 emissions and total system product cost (C˙ p) are carried out. It is demonstrated that the system’s evaluation criteria have the highest and lowest sensitivity to the variation of reformer temperature and ORC pressure respectively. From the triple-objective optimization procedure the decision variables including reformer temperature ORC pressure Rankine cycle I pressure and Rankine cycle II pressure are 544 ◦C 4.35 bar 158.12 bar and 52.82 bar respectively. At these conditions the total hybrid system’s energy efficiency exergy efficiency exergy destruction net generated power and total investment cost rate are 45.96% 46.83% 215.72 MW 203.67 MW and 9791 $/h respectively. The findings of this paper conclude that it is necessary to address all objective functions simultaneously in the system’s ultimate optimum design. Furthermore the objective of this paper becomes even more apparent when there is no choice but to cut greenhouse gas emissions while also addressing the rising global energy demand.
Energy and Economic Costs of Chemical Storage
May 2020
Publication
The necessity of neutralizing the increase of the temperature of the atmosphere by the reduction of greenhouse gas emissions in particular carbon dioxide (CO2) as well as replacing fossil fuels leads to a necessary energy transition that is already happening. This energy transition requires the deployment of renewable energies that will replace gradually the fossil fuels. As the renewable energy share increases energy storage will become key to avoid curtailment or polluting back-up systems. This paper considers a chemical storage process based on the use of electricity to produce hydrogen by electrolysis of water. The obtained hydrogen (H2) can then be stored directly or further converted into methane (CH4 from methanation if CO2 is available e.g. from a carbon capture facility) methanol (CH3OH again if CO2 is available) and/or ammonia (NH3 by an electrochemical process). These different fuels can be stored in liquid or gaseous forms and therefore with different energy densities depending on their physical and chemical nature. This work aims at evaluating the energy and the economic costs of the production storage and transport of these different fuels derived from renewable electricity sources. This applied study on chemical storage underlines the advantages and disadvantages of each fuel in the frame of the energy transition.
Hydrogen Bubble Growth in Alkaline Water Electrolysis: An Immersed Boundary Simulation Study
Nov 2022
Publication
Enhancing the efficiency of industrial water electrolysis for hydrogen production is important for the energy transition. In electrolysis hydrogen is produced at the cathode which forms bubbles due to the diffusion of dissolved hydrogen in the surrounding supersaturated electrolyte. Hydrogen (and oxygen) bubbles play an important role in the achievable electrolysis efficiency. The growth of the bubbles is determined by diffusive and convective mass transfer. In turn the presence and the growth of the hydrogen bubbles affect the electrolysis process at the cathode.<br/>In the present study we simulate the growth of a single hydrogen bubble attached to a vertical cathode in a 30 wt KOH solution in a cathodic compartment represented by a narrow channel. We solve the Navier-Stokes equations mass transport equations and potential equation for a tertiary current distribution. A sharp interface immersed boundary method with an artificial compressibility method for the pressure is employed. To verify the numerical accuracy of the method we performed a grid refinement study and checked the global momentum and hydrogen mass balances. We investigate the effects of flow rate and operation pressure upon bubble growth behaviour species concentrations potential and current density. We compare different cases in two ways: for the same time and for the same bubble radius. We observe that increasing the flow velocity leads to a small increase in efficiency. Increasing the operation pressure causes higher hydrogen density which slows down the bubble growth. It is remarkable that for a given bubble radius increasing the pressure leads to a small decrease in efficiency.
No more items...