Production & Supply Chain
Business Models for Low Carbon Hydrogen Production: A Report for BEIS
Aug 2020
Publication
Low carbon hydrogen could have a significant role to play in meeting the UK’s Net Zero target: the Committee on Climate Change (CCC) estimates that up to 270TWh of low carbon hydrogen could be needed in its ‘Further Ambition’ scenario. However at present there is no large-scale production of low carbon hydrogen in the UK not least as it is more costly than most high carbon alternatives. For hydrogen to be the viable option envisaged by the CCC projects may need to be deployed from the 2020s.<br/>BEIS has commissioned Frontier Economics to develop business models to support low carbon hydrogen production. This report builds on the earlier Carbon Capture Usage and Storage (CCUS) business models consultation2 and develops business models for BEIS to consider further. This report is a milestone in BEIS’ longer term process of developing hydrogen business models. It forms a part of BEIS’ wider research into a range of decarbonisation options across the economy.<br/>Further analysis will be required before a final decision is made.
Comparison Between Carbon Molecular Sieve and Pd-Ag Membranes in H2-CH4 Separation at High Pressure
Aug 2020
Publication
From a permeability and selectivity perspective supported thin-film Pd–Ag membranes are the best candidates for high-purity hydrogen recovery for methane-hydrogen mixtures from the natural gas grid. However the high hydrogen flux also results in induced bulk-to-membrane mass transfer limitations (concentration polarization) especially when working at low hydrogen concentration and high pressure which further reduces the hydrogen permeance in the presence of mixtures. Additionally Pd is a precious metal and its price is lately increasing dramatically. The use of inexpensive CMSM could become a promising alternative. In this manuscript a detailed comparison between these two membrane technologies operating under the same working pressure and mixtures is presented.<br/>First the permeation properties of CMSM and Pd–Ag membranes are compared in terms of permeance and purity and subsequently making use of this experimental investigation an economic evaluation including capital and variable costs has been performed for a separation system to recover 25 kg/day of hydrogen from a methane-hydrogen mixture. To widen the perspective also a sensitivity analysis by changing the pressure difference membrane lifetime membrane support cost and cost of Pd/Ag membrane recovery has been considered. The results show that at high pressure the use of CMSM is to more economic than the Pd-based membranes at the same recovery and similar purity.
Hydrogen Energy
Feb 2007
Publication
The problem of anthropogenically driven climate change and its inextricable link to our global society’s present and future energy needs are arguably the greatest challenge facing our planet. Hydrogen is now widely regarded as one key element of a potential energy solution for the twenty-first century capable of assisting in issues of environmental emissions sustainability and energy security. Hydrogen has the potential to provide for energy in transportation distributed heat and power generation and energy storage systems with little or no impact on the environment both locally and globally. However any transition from a carbon-based (fossil fuel) energy system to a hydrogen-based economy involves significant scientific technological and socio-economic barriers. This brief report aims to outline the basis of the growing worldwide interest in hydrogen energy and examines some of the important issues relating to the future development of hydrogen as an energy vector.
Link to document download on Royal Society Website
Link to document download on Royal Society Website
A Numerical Performance Study of a Fixed-bed Reactor for Methanol Synthesis by CO2 Hydrogenation
Mar 2021
Publication
Synthetic fuels are needed to replace their fossil counterparts for clean transport. Presently their production is still inefficient and costly. To enhance the process of methanol production from CO2 and H2 and reduce its cost a particle-resolved numerical simulation tool is presented. A global surface reaction model based on the Langmuir-Hinshelwood-Hougen-Watson kinetics is utilized. The approach is first validated against standard benchmark problems for non-reacting and reacting cases. Next the method is applied to study the performance of methanol production in a 2D fixed-bed reactor under a range of parameters. It is found that methanol yield enhances with pressure catalyst loading reactant ratio and packing density. The yield diminishes with temperature at adiabatic conditions while it shows non-monotonic change for the studied isothermal cases. Overall the staggered and the random catalyst configurations are found to outperform the in-line system.
End of Life of Fuel Cells and Hydrogen Products: From Technologies to Strategies
Feb 2019
Publication
End-of-Life (EoL) technologies and strategies are needed to support the deployment of fuel cells and hydrogen (FCH) products. This article explores current and novel EoL technologies to recover valuable materials from the stacks of proton exchange membrane fuel cells and water electrolysers alkaline water electrolysers and solid oxide fuel cells. Current EoL technologies are mainly based on hydrometallurgical and pyro-hydrometallurgical methods for the recovery of noble metals while novel methods attempt to recover additional materials through efficient safe and cost-competitive pathways. Strengths weaknesses opportunities and threats of the reviewed EoL technologies are identified under techno-economic environmental and regulatory aspects. Beyond technologies strategies for the EoL of FCH stacks are defined mainly based on the role of manufacturers and recovery centres in the short- mid- and long-term. In this regard a dual role manufacturer/recovery centre would characterise long-term scenarios within a potential context of a well-established hydrogen economy.
Hydrogen Production by Electrochemical Reaction Using Ethylene Glycol with Terephthalic Acid
Jan 2021
Publication
In this study ethylene glycol (EG) and terephthalic acid (TPA) were used to generate hydrogen using copper electrodes in an alkaline aqueous solution and the corresponding reaction mechanism was experimentally investigated. Both EG and TPA produced hydrogen; however TPA consumed OH− inhibiting the production of intermediary compounds of EG and causing EG to actively react with H2O ultimately leading to enhanced hydrogen production. In addition the initiation potential of water decomposition of the EG and TPA alkaline aqueous solution was 1.0 V; when 1.8 V (vs. RHE) was applied the hydrogen production reached 440 mmol L−1 which was substantially greater than the hydrogen production rate of 150 mmol L−1 during water decomposition.
The Role of the Substrate on the Mechanical and Thermal Stability of Pd Thin Films During Hydrogen (De)sorption
Nov 2020
Publication
In this work we studied the mechanical and thermal stability of ~100 nm Pd thin films magnetron sputter deposited on a bare oxidized Si(100) wafer a sputtered Titanium (Ti) intermediate layer and a spin-coated Polyimide (PI) intermediate layer. The dependence of the film stability on the film morphology and the film-substrate interaction was investigated. It was shown that a columnar morphology with elongated voids at part of the grain boundaries is resistant to embrittlement induced by the hydride formation (α↔β phase transitions). For compact film morphology depending on the rigidity of the intermediate layer and the adherence to the substrate complete transformation (Pd-PI-SiO2/Si) or partly suppression (Pd-Ti-SiO2/Si) of the α to β-phase was observed. In the case of Pd without intermediate layer (Pd-SiO2/Si) buckling delamination occurred. The damage and deformation mechanisms could be understood by the analysis of the stresses and dislocation (defects) behavior near grain boundaries and the film-substrate interface. From diffraction line-broadening combined with microscopy analysis we showed that in Pd thin films stresses relax at critical stress values via different relaxation pathways depending on film-microstructure and film-substrate interaction. On the basis of the in-situ hydriding experiments it was concluded that a Pd film on a flexible PI intermediate layer exhibits free-standing film-like behavior besides being strongly clamped on a stiff SiO2/Si substrate.
Plasmonic Nickel Nanoparticles Decorated on to LaFeO3 Photocathode for Enhanced Solar Hydrogen Generation
Nov 2018
Publication
Plasmonic Ni nanoparticles were incorporated into LaFeO3 photocathode (LFO-Ni) to excite the surface plasmon resonances (SPR) for enhanced light harvesting for enhancing the photoelectrochemical (PEC) hydrogen evolution reaction. The nanostructured LFO photocathode was prepared by spray pyrolysis method and Ni nanoparticles were incorporated on to the photocathode by spin coating technique. The LFO-Ni photocathode demonstrated strong optical absorption and higher current density where the untreated LFO film exhibited a maximum photocurrent of 0.036 mA/cm2 at 0.6 V vs RHE and when incorporating 2.84 mmol Ni nanoparticles the photocurrent density reached a maximum of 0.066 mA/cm2 at 0.6 V vs RHE due to the SPR effect. This subsequently led to enhanced hydrogen production where more than double (2.64 times) the amount of hydrogen was generated compared to the untreated LFO photocathode. Ni nanoparticles were modelled using Finite Difference Time Domain (FDTD) analysis and the results showed optimal particle size in the range of 70–100 nm for Surface Plasmon Resonance (SPR) enhancement.
Progress in Catalytic Hydrogen Production from Formic Acid over Supported Metal Complexes
Mar 2021
Publication
Formic acid is a liquid organic hydrogen carrier giving hydrogen on demand using catalysts. Metal complexes are known to be used as efficient catalysts for the hydrogen production from formic acid decomposition. Their performance could be better than those of supported catalysts with metal nanoparticles. However difficulties to separate metal complexes from the reaction mixture limit their industrial applications. This problem can be resolved by supporting metal complexes on the surface of different supports which may additionally provide some surface sites for the formic acid activation. The review analyzes the literature on the application of supported metal complexes in the hydrogen production from formic acid. It shows that the catalytic activity of some stable Ru and Ir supported metal complexes may exceed the activity of homogeneous metal complexes used for deposition. Non-noble metal-based complexes containing Fe demonstrated sufficiently high performance in the reaction; however they can be poisoned by water present in formic acid. The proposed review could be useful for development of novel catalysts for the hydrogen production.
High-pressure Hydrogen Production with Inherent Sequestration of a Pure Carbon Dioxide Stream Via Fixed Bed Chemical Looping
Feb 2019
Publication
The proof of concept for the production of pure pressurized hydrogen from hydrocarbons in combination with the sequestration of a pure stream of carbon dioxide with the reformer steam iron cycle is presented. The iron oxide based oxygen carrier (95% Fe2O3 5% Al2O3) is reduced with syngas and oxidized with steam at 1023 K. The carbon dioxide separation is achieved via partial reduction of the oxygen carrier from Fe2O3 to Fe3O4 yielding thermodynamically to a product gas only containing CO2 and H2O. By the subsequent condensation of steam pure CO2 is sequestrated. After each steam oxidation phase an air oxidation was applied to restore the oxygen carrier to hematite level. Product gas pressures of up to 30.1 bar and hydrogen purities exceeding 99% were achieved via steam oxidations. The main impurities in the product gas are carbon monoxide and carbon dioxide which originate from solid carbon depositions or from stored carbonaceous molecules inside the pores of the contact mass. The oxygen carrier samples were characterized using elemental analysis BET surface area measurement XRD powder diffraction SEM and light microscopy. The maximum pressure of 95 bar was demonstrated for hydrogen production in the steam oxidation phase after the full oxygen carrier reduction significantly reducing the energy demand for compressors in mobility applications.
Recent Advances in Biomass Pretreatment Technologies for Biohydrogen Production
Jan 2022
Publication
Hydrogen is an economical source of clean energy that has been utilized by industry for decades. In recent years demand for hydrogen has risen significantly. Hydrogen sources include water electrolysis hydrocarbon steam reforming and fossil fuels which emit hazardous greenhouse gases and therefore have a negative impact on global warming. The increasing worldwide population has created much pressure on natural fuels with a growing gap between demand for renewable energy and its insufficient supply. As a result the environment has suffered from alarming increases in pollution levels. Biohydrogen is a sustainable energy form and a preferable substitute for fossil fuel. Anaerobic fermentation photo fermentation microbial and enzymatic photolysis or combinations of such techniques are new approaches for producing biohydrogen. For cost-effective biohydrogen production the substrate should be cheap and renewable. Substrates including algal biomass agriculture residue and wastewaters are readily available. Moreover substrates rich in starch and cellulose such as plant stalks or agricultural waste or food industry waste such as cheese whey are reported to support dark- and photo-fermentation. However their direct utilization as a substrate is not recommended due to their complex nature. Therefore they must be pretreated before use to release fermentable sugars. Various pretreatment technologies have been established and are still being developed. This article focuses on pretreatment techniques for biohydrogen production and discusses their efficiency and suitability including hybrid-treatment technology
Magnetic Field Enhancement of Electrochemical Hydrogen Evolution Reaction Probed by Magneto-optics
Nov 2020
Publication
External magnetic fields affect various electrochemical processes and can be used to enhance the efficiency of the electrochemical water splitting reaction. However the driving forces behind this effect are poorly understood due to the analytical challenges of the available interface-sensitive techniques. Here we present a set-up based on magneto- and electro-optical probing which allows to juxtapose the magnetic properties of the electrode with the electrochemical current densities in situ at various applied potentials and magnetic fields. On the example of an archetypal hydrogen evolution catalyst Pt (in a form of Co/Pt superlattice) we provide evidence that a magnetic field acts on the electrochemical double layer affecting the local concentration gradient of hydroxide ions which simultaneously affects the magneto-optical and magnetocurrent response.
Palladium (Pd) Membranes as Key Enabling Technology for Pre-combustion CO2 Capture and Hydrogen Production
Aug 2017
Publication
Palladium (Pd) membranes are a promising enabling technology for power generation and hydrogen production with CO2 capture. SINTEF has developed and patented a flexible technology to produce Pd-alloy membranes that significantly improves flux and thereby reduces material costs. Reinertsen AS and SINTEF aim to demonstrate the Pd membrane technology for H2 separation on a side stream of the Statoil Methanol Plant at Tjeldbergodden Norway. In the present article we present the upscaling of the membrane manufacturing process together with the membrane module and skid design and construction.
Ammonia-hydrogen Combustion in a Swirl Burner with Reduction of NOx Emissions
Sep 2019
Publication
Recently ammonia is being considered for fuelling gas turbines as a new sustainable source. It can undergo thermal cracking producing nitrogen hydrogen and unburned ammonia thus enabling the use of these chemicals most efficiently for combustion purposes. Ammonia being carbon-free may allow the transition towards a hydrogen economy. However one of the main constraints of this fuelling technique is that although the combustion of ammonia produces no CO2 there is a large NOx proportion of emissions using this fuel. In this work cracked ammonia obtained from a modified combustion rig designed at Cardiff University was used to simulate a swirl burner under preheating conditions via heat exchangers. The primary objective of this system is to find new ways for the reduction of NOx emissions by injecting various amounts of ammonia/hydrogen at different mixtures downstream of the primary flame zone. The amount of injected ammonia/hydrogen mixture (X) taken from the thermal cracking system was ranged from 0%-4% (vol %) of the total available fuel in the system while the remaining gas (1.00-X) was then employed as primary fuel into the burner. CHEMKIN- PRO calculations were conducted by employing a novel chemical reaction code developed at Cardiff University to achieve the goal of this paper. The predictions were performed under low pressure and rich conditions with an equivalence ratio ϕ =1.2 in a swirl burner previously characterised at output powers of ~10 kW. Ammonia and hydrogen blends were evaluated from 50% NH3 (vol %) with the remaining gas as hydrogen continuing in steps of 10% (vol %) NH3 increments. Results showed that the minimum unburned ammonia and higher flame temperature were achieved at 60%-40% NH3-H2 when compared to other blends but with high NO emissions. These NO levels were reduced by injecting a small amount of NH3/H2 mixture (X=4 %) downstream the primary zone in a generated circulations promoted by the new design of the burner which affecting the residence time hence reducing the NO emission in the exhaust gas.
Direct Conversion of CO2 to Dimethyl Ether in a Fixed Bed Membrane Reactor: Influence of Membrane Properties and Process Conditions
Jun 2021
Publication
The direct hydrogenation of CO2 to dimethyl ether (DME) is a promising technology for CO2 valorisation. In this work a 1D phenomenological reactor model is developed to evaluate and optimize the performance of a membrane reactor for this conversion otherwise limited by thermodynamic equilibrium and temperature gradients. The co-current circulation of a sweep gas stream through the permeation zone promotes both water and heat removal from the reaction zone thus increasing overall DME yield (from 44% to 64%). The membrane properties in terms of water permeability (i.e. 4·10−7 mol·Pa−1m−2s−1) and selectivity (i.e. 50 towards H2 30 towards CO2 and CO 10 towards methanol) for optimal reactor performance have been determined considering for the first time non-ideal separation and non-isothermal operation. Thus this work sheds light into suitable membrane materials for this applications. Then the non-isothermal performance of the membrane reactor was analysed as a function of the process parameters (i.e. the sweep gas to feed flow ratio the gradient of total pressure across the membrane the inlet temperature to the reaction and permeation zone and the feed composition). Owing to its ability to remove 96% of the water produced in this reaction the proposed membrane reactor outperforms a conventional packed bed for the same application (i.e. with 36% and 46% improvement in CO2 conversion and DME yield respectively). The results of this work demonstrate the potential of the membrane reactor to make the CO2 conversion to DME a feasible process.
Analysis of Hydrogen Production Potential from Waste Plastics by Pyrolysis and In Line Oxidative Steam Reforming
Oct 2021
Publication
A study was carried out on the valorization of different waste plastics (HDPE PP PS and PE) their mixtures and biomass/HDPE mixtures by means of pyrolysis and in line oxidative steam reforming. A thermodynamic equilibrium simulation was used for determining steam reforming data whereas previous experimental results were considered for setting the pyrolysis volatile stream composition. The adequacy of this simulation tool was validated using experimental results obtained in the pyrolysis and in line steam reforming of different plastics. The effect the most relevant process conditions i.e. temperature steam/plastic ratio and equivalence ratio have on H2 production and reaction enthalpy was evaluated. Moreover the most suitable conditions for the oxidative steam reforming of plastics of different nature and their mixtures were determined. The results obtained are evidence of the potential interest of this novel valorization route as H2 productions of up to 25 wt% were obtained operating under autothermal conditions.
Experimental Characterization of an Alkaline Electrolyser and a Compression System for Hydrogen Production and Storage
Aug 2021
Publication
Storing renewable energy in chemicals like hydrogen can bring various benefits like high energy density seasonal storability possible cost reduction of the final product and the potential to let renewable power penetrate other markets and to overcome their intermittent availability. In the last year’s production of this gas from renewable energy sources via electrolysis has grown its reputation as one feasible solution to satisfy future zero-emission energy demand. To extend the exploitation of Renewable Energy Source (RES) small-scale conversion plants seem to be an interesting option. In view of a possible widespread adoption of these types of plants the authors intend to present the experimental characterization of a small-scale hydrogen production and storage plant. The considered experimental plant is based on an alkaline electrolyser and an air-driven hydrogen compression and storage system. The results show that the hydrogen production-specific consumption is on average 77 kWh/kgH2 . The hydrogen compressor energy requirement is on average 15 kWh/kgH2 (data referred to the driving compressed air). The value is higher than data found in literature (4.4–9.3 kWh/kgH2 ) but the difference can be attributed to the small size of the considered compressor and the choice to limit the compression stages.
Small-Scaled Production of Blue Hydrogen with Reduced Carbon Footprint
Aug 2021
Publication
This article reviews a method of hydrogen production based on partial non-catalytic oxidation of natural gas in an original synthesis gas generator. The working principles of the unit are similar to those of liquid-propellant rocket engines. This paper presents a description of the operation and technical characteristics of the synthesis gas generator. Its application in the creation of small-scaled plants with a capacity of up to 5–7 thousand m3/h of hydrogen is justified. Hydrogen production in the developed installation requires a two-stage method and includes a technological unit for producing a hydrogen-containing gas. Typical balance compositions of hydrogen-containing gas at the synthesis gas generator’s outlet are given. To increase the hydrogen concentration it is proposed to carry out a two-stage steam catalytic conversion of carbon monoxide contained in the hydrogen-containing gas at the synthesis gas generator’s outlet using a single Cu–Zn–cementcontaining composition. Based on thermodynamic calculations quasi-optimal modes of natural gas partial oxidation with oxygen are formulated and the results of material balance calculation for the installation are presented. In order to produce “blue” hydrogen the scheme of carbon dioxide separation and liquefaction is developed. The conclusion section of the paper contains the test results of a pilot demonstration unit and the recommendations for improving the technology and preventing soot formation.
Electrolyzers Enhancing Flexibility in Electric Grids
Nov 2017
Publication
This paper presents a real-time simulation with a hardware-in-the-loop (HIL)-based approach for verifying the performance of electrolyzer systems in providing grid support. Hydrogen refueling stations may use electrolyzer systems to generate hydrogen and are proposed to have the potential of becoming smarter loads that can proactively provide grid services. On the basis of experimental findings electrolyzer systems with balance of plant are observed to have a high level of controllability and hence can add flexibility to the grid from the demand side. A generic front end controller (FEC) is proposed which enables an optimal operation of the load on the basis of market and grid conditions. This controller has been simulated and tested in a real-time environment with electrolyzer hardware for a performance assessment. It can optimize the operation of electrolyzer systems on the basis of the information collected by a communication module. Real-time simulation tests are performed to verify the performance of the FEC-driven electrolyzers to provide grid support that enables flexibility greater economic revenue and grid support for hydrogen producers under dynamic conditions. The FEC proposed in this paper is tested with electrolyzers however it is proposed as a generic control topology that is applicable to any load.
The Challenges of Integrating the Principles of Green Chemistry and Green Engineering to Heterogeneous Photocatalysis to Treat Water and Produce Green H2
Jan 2023
Publication
Nowadays heterogeneous photocatalysis for water treatment and hydrogen production are topics gaining interest for scientists and developers from different areas such as environmental technology and material science. Most of the efforts and resources are devoted to the development of new photocatalyst materials while the modeling and development of reaction systems allowing for upscaling the process to pilot or industrial scale are scarce. In this work we present what is known on the upscaling of heterogeneous photocatalysis to purify water and to produce green H2. The types of reactors successfully used in water treatment plants are presented as study cases. The challenges of upscaling the photocatalysis process to produce green H2 are explored from the perspectives of (a) the adaptation of photoreactors (b) the competitiveness of the process and (c) safety. Throughout the text Green Chemistry and Engineering Principles are described and discussed on how they are currently being applied to the heterogeneous photocatalysis process along with the challenges that are ahead. Lastly the role of automation and high-throughput methods in the upscaling following the Green Principles is discussed.
Modeling of Thermal Performance of a Commercial Alkaline Electrolyzer Supplied with Various Electrical Currents
Nov 2021
Publication
Hydrogen produced by solar and other clean energy sources is an essential alternative to fossil fuels. In this study a commercial alkaline electrolyzer with different cell numbers and electrode areas are simulated for different pressure temperature thermal resistance and electrical current. This alkaline electrolyzer is considered unsteady in simulations and different parameters such as temperature are obtained in terms of time. The obtained results are compared with similar results in the literature and good agreement is observed. Various characteristics of this alkaline electrolyzer as thermoneutral voltage faraday efficiency and cell voltage are calculated and displayed. The outlet heat rate and generated heat rate are obtained as well. The pressure and the temperature in the simulations are between 1 and 100 bar and between 300 and 360 Kelvin respectively. The results show that the equilibrium temperature is reached 2-3 hours after the time when the Alkaline electrolyzer starts to work.
Flare Gas Monetization and Greener Hydrogen Production via Combination with Crypto Currency Mining and Carbon Dioxide Capture
Jan 2022
Publication
In view of the continuous debates on the environmental impact of blockchain technologies in particular crypto currency mining accompanied by severe carbon dioxide emissions a technical solution has been considered assuming direct monetization of associated petroleum gas currently being flared. The proposed approach is based on the technology of low-temperature steam reforming of hydrocarbons which allows flare gas conditioning towards the requirements for fuel for gas piston and gas turbine power plants. The generation of electricity directly at the oil field and its use for on-site crypto currency mining transforms the process of wasteful flaring of valuable hydrocarbons into an economically attractive integrated processing of natural resources. The process is not carbon neutral and is not intended to compete zero-emission technologies but its combination with technologies for carbon dioxide capture and re-injection into the oil reservoir can both enhance the oil recovery and reduce carbon dioxide emissions into the atmosphere. The produced gas can be used for local transport needs while the generated heat and electricity can be utilized for on-site food production and biological carbon dioxide capture in vertical greenhouse farms. The suggested approach allows significant decrease in the carbon dioxide emissions at oil fields and although it may seem paradoxically on-site cryptocurrency mining actually may lead to a decrease in the carbon footprint. The amount of captured CO2 could be transformed into CO2 emission quotas which can be spent for the production of virtually “blue” hydrogen by steam reforming of natural gas in locations where the CO2 capture is technically impossible and/or unprofitable.
The Potential of Green Ammonia Production to Reduce Renewable Power Curtailment and Encourage the Energy Transition in China
Apr 2022
Publication
The pursuing of inter-regional power transmission to address renewable power curtailment in China has resulted in disappointing gains. This paper evaluates the case of local green ammonia production to address this issue. An improved optimization-based simulation model is applied to simulate lifetime green manufacturing and the impacts of main institutional incentives and oxygen synergy on investment are analysed. Levelized cost of ammonia is estimated at around 820 USD/t which is about twice the present price. The operating rate ammonia price the electrical efficiency of electrolysers and the electricity price are found to be the key factors in green ammonia investment. Carbon pricing and value-added tax exemption exert obvious influences on the energy transition in China. A subsidy of approximately 450 USD/t will be required according to the present price; however this can be reduced by 100 USD/t through oxygen synergy. Compared to inter-regional power transmission green ammonia production shows both economic and environmental advantages. Therefore we propose an appropriate combination of both options to address renewable power curtailment and the integration of oxygen manufacturing into hydrogen production. We consider the findings and policy implications will contribute to addressing renewable power curtailment and boosting the hydrogen economy in China.
Laser Induced Hydrogen Emission from Ethanol with Dispersed Graphene Particles
Apr 2021
Publication
Efficient hydrogen emission from ethanol with disperse graphene foam particles by using a continuous wave infrared laser diode is reported. The products of ethanol dissociation - hydrogen methane and carbon oxide were measured using mass spectrometry. It was found that the most efficient generation of hydrogen was observed when graphene particles were irradiated by a focused laser beam proceeded at the surface of ethanol solution. The process was assisted by intense white light emission resulting from the laser induced multiphoton ionization of graphene combined with the simultaneous emission of hot electrons. The hot electron emission enables the efficient dissociation of ethanol molecules located close to the solution surface with graphene foam particles.
Synthesis and Performance of Photocatalysts for Photocatalytic Hydrogen Production: Future Perspectives
Dec 2021
Publication
Photocatalysis for “green” hydrogen production is a technology of increasing importance that has been studied using both TiO2–based and heterojunction composite-based semiconductors. Different irradiation sources and reactor units can be considered for the enhancement of photocatalysis. Current approaches also consider the use of electron/hole scavengers organic species such as ethanol that are “available” in agricultural waste in communities around the world. Alternatively organic pollutants present in wastewaters can be used as organic scavengers reducing health and environmental concerns for plants animals and humans. Thus photocatalysis may help reduce the carbon footprint of energy production by generating H2 a friendly energy carrier and by minimizing water contamination. This review discusses the most up-to-date and important information on photocatalysis for hydrogen production providing a critical evaluation of: (1) The synthesis and characterization of semiconductor materials; (2) The design of photocatalytic reactors; (3) The reaction engineering of photocatalysis; (4) Photocatalysis energy efficiencies; and (5) The future opportunities for photocatalysis using artificial intelligence. Overall this review describes the state-of-the-art of TiO2–based and heterojunction composite-based semiconductors that produce H2 from aqueous systems demonstrating the viability of photocatalysis for “green” hydrogen production.
Integrating IT-SOFC and Gasification Combined Cycle with Methanation Reactor and Hydrogen Firing for Near Zero-emission Power Generation from Coal
Apr 2011
Publication
Application of Solid Oxide Fuel Cells (SOFC) in gasification-based power plants would represent a turning point in the power generation sector allowing to considerably increase the electric efficiency of coal-fired power stations while reducing CO2 and other pollutant emissions. The aim of this paper is the thermodynamic assessment of a SOFC-based IGFC plant with methanation reactor hydrogen post-firing and CO2 capture by physical absorption. The configuration proposed allows to obtain a very high net efficiency (51.6%) overcoming the main limits of configurations assessed in previous works.
Enhancing the Efficiency of Power- and Biomass-to-liquid Fuel Processes Using Fuel-assisted Solid Oxide Electrolysis Cells
Apr 2022
Publication
Power- and biomass-to-liquid fuel processes (PBtL) can utilize renewable energy and residual forestry waste to produce liquid synthetic fuels which have the potential to mitigate the climate impacts of the current transportation infrastructure including the long-haul aviation sector. In a previous study we demonstrated that implementing a solid oxide electrolysis cell (SOEC) in the PBtL process can significantly increase the energy efficiency of fuel production by supplying the produced hydrogen to a reverse water gas shift (RWGS) reactor to generate syngas which is then fed downstream to a Fischer–Tropsch (FT) reactor. The tail gas emitted from the FT reactor consists primarily of a mixture of hydrogen carbon monoxide and methane and is often recycled to the entrained flow gasifier located at the beginning of the process. In this analysis we investigate the efficiency gains of the PBtL process as a result of redirecting the tail gas of the FT reactor to the anode of an SOEC to serve as fuel. Supplying fuel to an SOEC can lower the electrical work input required to facilitate steam electrolysis when reacting electrochemically with oxide ions in the anode which in turn can reduce oxygen partial pressures and thus alleviate material degradation. Accordingly we develop a thermodynamic framework to reveal the performance limits of fuel-assisted SOECs (FASOECs) and provide strategies to minimize oxygen partial pressures in the SOEC anode. Additionally we elucidate how much fuel is required to match the heating demands of a cell when steam is supplied to the cathode over a broad range of inlet temperatures and demonstrate the influence of a set of reaction pathways of the supplied fuel on the operating potential of an FASOEC and the corresponding efficiency gain of the PBtL process. Based on preliminary calculations we estimate that implementing an FASOEC in the PBtL process can increase the energy efficiency of fuel production to more than 90% depending on the amount of FT tail gas available to the system.
To Adopt CCU Technology or Not? An Evolutionary Game between Local Governments and Coal-Fired Power Plants
Apr 2022
Publication
Carbon dioxide capture and utilization (CCU) technology is a significant means by which China can achieve its ambitious carbon neutrality goal. It is necessary to explore the behavioral strategies of relevant companies in adopting CCU technology. In this paper an evolutionary game model is established in order to analyze the interaction process and evolution direction of local governments and coal-fired power plants. We develop a replicator dynamic system and analyze the stability of the system under different conditions. Based on numerical simulation we analyze the impact of key parameters on the strategies of stakeholders. The simulation results show that the unit prices of hydrogen and carbon dioxide derivatives have the most significant impact: when the unit price of hydrogen decreases to 15.9 RMB/kg or the unit price of carbon dioxide derivatives increases to 3.4 RMB/kg the evolutionary stabilization strategy of the system changes and power plants shift to adopt CCU technology. The results of this paper suggest that local governments should provide relevant support policies and incentives for CCU technology deployment as well as focusing on the synergistic development of CCU technology and renewable energy hydrogen production technology
Probability of Occurrence of ISO 14687-2 Contaminants in Hydrogen: Principles and Examples from Steam Methane Reforming and Electrolysis (Water and Chlor-alkali) Production Processes Model
Apr 2018
Publication
According to European Directive 2014/94/EU hydrogen providers have the responsibility to prove that their hydrogen is of suitable quality for fuel cell vehicles. Contaminants may originate from hydrogen production transportation refuelling station or maintenance operation. This study investigated the probability of presence of the 13 gaseous contaminants (ISO 14687-2) in hydrogen on 3 production processes: steam methane reforming (SMR) process with pressure swing adsorption (PSA) chlor-alkali membrane electrolysis process and water proton exchange membrane electrolysis process with temperature swing adsorption. The rationale behind the probability of contaminant presence according to process knowledge and existing barriers is highlighted. No contaminant was identified as possible or frequent for the three production processes except oxygen (frequent for chlor-alkali membrane process) carbon monoxide (frequent) and nitrogen (possible) for SMR with PSA. Based on it a hydrogen quality assurance plan following ISO 19880-8 can be devised to support hydrogen providers in monitoring the relevant contaminants.
Hydrogen Production Using Solar Energy - Technical Analysis
Mar 2019
Publication
This paper presents a case study concerning a plant for hydrogen production and storage having a daily capacity of 100kg. The plant is located in Cluj-Napoca Romania. It produces hydrogen by means of water electrolysis while the energy is provided using solar energy. We performed the calculations for four different technical solutions used for the hydrogen production and storage plant and also we considered three scenarios regarding the sub-systems of the hydrogen production and storage plant efficiency. The conclusion of this study is that one can maximize the conversion of solar radiation into chemical energy in the form of hydrogen by hybridizing the solar hydrogen production system namely using both electrical energy as well as thermal energy in the form of steam.
Hydrogen Production from Biomass and Organic Waste Using Dark Fermentation: An Analysis of Literature Data on the Effect of Operating Parameters on Process Performance
Jan 2022
Publication
In the context of hydrogen production from biomass or organic waste with dark fermentation this study analysed 55 studies (339 experiments) in the literature looking for the effect of operating parameters on the process performance of dark fermentation. The effect of substrate concentration pH temperature and residence time on hydrogen yield productivity and content in the biogas was analysed. In addition a linear regression model was developed to also account for the effect of nature and pretreatment of the substrate inhibition of methanogenesis and continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration short residence time and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield productivity and content were respectively 6.49% COD COD−1 135 mg L−1 d −1 51% v/v while 10% of the considered experiments obtained yield productivity and content of or higher than 15.55% COD COD−1 305.16 mg L−1 d −1 64% v/v. Overall this study provides insight into how to select the optimum operating conditions to obtain the desired hydrogen production.
Achieving High-rate Hydrogen Recovery from Wastewater Using Customizable Alginate Polymer Gel Matrices Encapsulating Biomass
Jul 2018
Publication
In addition to methane gas higher-value resources such as hydrogen gas are produced during anaerobic wastewater treatment. They are however immediately consumed by other organisms. To recover these high-value resources not only do the desired phenotypes need to be retained in the anaerobic reactor but the undesired ones need to be washed out. In this study a well-established alginate-based polymer gel with and without a coating layer was used to selectively encapsulate hydrogen-producing biomass in beads to achieve high-rate recovery of hydrogen during anaerobic wastewater treatment. The effect of cross-linking agents Ca2+ Sr2+ and Ba2+ as well as a composite coating on the beads consisting of alternating layers of polyethylenimine and silica hydrogel were investigated with respect to their performance specifically their mass transfer characteristics and their differential ability to retain the encapsulated biomass. Although the coating reduced the escape rate of encapsulated biomass from the beads all alginate polymer matrices without coating effectively retained biomass. Fast diffusion of dissolved organic carbon (DOC) through the polymer gel was observed in both Ca-alginate and Sr-alginate without coating. The coating however decreased either the diffusivity or the permeability of the DOC depending on whether the DOC was from synthetic wastewater (more lipids and proteins) or real brewery wastewater (more sugars). Consequently the encapsulation system with coating became diffusion limited when brewery wastewater with high chemical oxygen demand was fed resulting in a lower hydrogen production rate than the uncoated encapsulation systems. In all cases the encapsulated biomass was able to produce hydrogen even at a hydraulic residence time of 45 min. Although there are limitations to this system the used of encapsulated biomass for resource recovery from wastewater shows promise particularly for high-rate systems in which the retention of specific phenotypes is desired.
Simple Hydrogen Gas Production Method Using Waste Silicon
Jan 2022
Publication
We investigated a simple and safe method for producing hydrogen using Si powder which is discarded in the semiconductor industry. Using the reaction of generating hydrogen from Si powder and an aqueous NaOH solution a simple hydrogen generator that imitated Kipp’s apparatus was produced. Then by combining this apparatus with a polymer electrolyte fuel cell an automatic hydrogen generation system based on the amount of electric power required was proposed. Furthermore it was found that hydrogen can also be generated using non-poisonous and deleterious substances Ca(OH)2 and Na2CO3 instead of the deleterious substance NaOH and adding water to the mixture with Si powder. The by-products Na2SiO3 and CaCO3 can be used as raw materials for glass. The simple hydrogen generator produced in this study can be used as a fuel supply source for small-scale power generation systems as an auxiliary power source.
H2FC SUPERGEN- Delivering Negative Emissions from Biomass derived Hydrogen
Apr 2020
Publication
Bioenergy with carbon capture and storage (BECCS) removes carbon dioxide (CO2) from the atmosphere i.e. negative CO2 emissions. It will likely have an important role in the transition to a net-zero economy by offsetting hard-to-abate greenhouse gas emissions. However there are concerns about the sustainability of large scale BECCS deployment using bioenergy from predominantly primary biomass sources (i.e. dedicated energy crops). Secondary sources of biomass (e.g. waste biomass municipal solid wastes forest/agricultural residues) are potentially an economical and sustainable alternative resource. Furthermore supplementing primary biomass demand with secondary sources could enable the supply of biomass from solely indigenous sources (i.e. from the UK) which could provide economic advantages in a growing global bio-economy.<br/><br/>There is also a growing interest in biomass-derived hydrogen production with CCS (BHCCS) which generates hydrogen and removes CO2 from the atmosphere. Hydrogen could help decarbonise fuel-dependent sectors such as heat industry or transportation. The aim of this study was to determine whether BHCCS could possibly deliver net negative CO2 emissions making comparisons against the other BECCS technologies.
Development and Functionalization of Visible-Light-Driven Water-Splitting Photocatalysts
Jan 2022
Publication
With global warming and the depletion of fossil resources our fossil fuel-dependent society is expected to shift to one that instead uses hydrogen (H2) as a clean and renewable energy. To realize this the photocatalytic water-splitting reaction which produces H2 from water and solar energy through photocatalysis has attracted much attention. However for practical use the functionality of water-splitting photocatalysts must be further improved to efficiently absorb visible (Vis) light which accounts for the majority of sunlight. Considering the mechanism of water-splitting photocatalysis researchers in the various fields must be employed in this type of study to achieve this. However for researchers in fields other than catalytic chemistry ceramic (semiconductor) materials chemistry and electrochemistry to participate in this field new reviews that summarize previous reports on water-splitting photocatalysis seem to be needed. Therefore in this review we summarize recent studies on the development and functionalization of Vis-light-driven water-splitting photocatalysts. Through this summary we aim to share current technology and future challenges with readers in the various fields and help expedite the practical application of Vis-light-driven water-splitting photocatalysts.
Multi-objective Optimal Configurations of a Membrane Reactor for Steam Methane Reforming
Nov 2021
Publication
The combination of traditional reactor and permeable membrane is beneficial to increase the production rate of the target product. How to design a high efficiency and energy saving membrane reactor is one of the key problems to be solved urgently. This paper utilizes finite-time thermodynamics and nonlinear programming to solve the optimal configurations of the membrane reactor of steam methane reforming (MR-SMR) for two optimization objectives that is heat exchange rate minimization and power consumption minimization. The exterior wall temperature and fixed hydrogen production rate are regarded as the control variable and constraint respectively. The results indicate that the hydrogen production rate and heat exchange rate in MR-SMR are increased by 108.58% and 58.42% respectively while the power consumption is reduced by 33.44% compared with those in the traditional reactor under the same condition. Compared with the results in reference reactor (MR-SMR obtained with initial values) the heat exchange rate is reduced by 1.40% by optimizing the exterior wall temperature and the power consumption is reduced by 5.10% by optimizing the exterior wall temperature and molar flow rate of sweep gas. The optimal distributions of exterior wall temperatures in the optimal reactors of minimum heat exchange rate and power consumption have a theoretical guiding significance for the thermal design of the membrane reactors.
Continuous Hydrogen Regeneration Through the Oxygen Vacancy Control of Metal Oxides Using Microwave Irradiation
Nov 2018
Publication
The amount of hydrogen gas generated from metal oxide materials based on a thermochemical water-splitting method gradually reduces as the surface of the metal oxide oxidizes during the hydrogen generation process. To regenerate hydrogen the oxygen reduction process of a metal oxide at high temperatures (1000–2500 °C) is generally required. In this study to overcome the problem of an energy efficiency imbalance in which the required energy of the oxygen reduction process for hydrogen regeneration is higher than the generated hydrogen energy we investigated the possibility of the oxygen reduction of a metal oxide with a low energy using microwave irradiation. For this purpose a macroporous nickel-oxide structure was used as a metal oxide catalyst to generate hydrogen gas and the oxidized surface of the macroporous nickel-oxide structure could be reduced by microwave irradiation. Through this oxidation reduction process ∼750 μmol g−1 of hydrogen gas could be continuously regenerated. In this way it is expected that oxygen-enriched metal oxide materials can be efficiently reduced by microwave irradiation with a low power consumption of <∼4% compared to conventional high-temperature heat treatment and thus can be used for efficient hydrogen generation and regeneration processes in the future.
Prospective Life Cycle Assessment of Hydrogen Production by Waste Photoreforming
Jan 2022
Publication
Identifying sustainable energy vectors is perhaps one of the most critical issues that needs addressing to achieve a climate-neutral society by 2050. In this context the hydrogen economy has been proposed as a solution to mitigate our current fossil-based energy system while the concept of the circular economy aims to boost the efficient use of resources. Photoreforming offers a promising opportunity for recycling and transforming widely available biomass-derived wastes (e.g. crude glycerol from biodiesel) into clean hydrogen fuel. This processing technology may be a versatile method that can be performed not only under UV light but also under visible light. However this approach is currently at the lab-scale and some inherent challenges must be overcome not least the relatively modest hydrogen production rates for the lamps’ substantial energy consumption. This study aims to assess the main environmental impacts identifying the hotspots and possible trade-off in which this technology could operate feasibly. We introduce an assessment of the windows of opportunity using seven categories of environmental impact with either artificial light or sunlight as the source of photocatalytic conversion. We compared the environmental indicators from this study with those of the benchmark water electrolysis and steam–methane reforming (SMR) technologies which are currently operating at a commercial scale. The results obtained in this study situate biowaste photoreforming within the portfolio of sustainable H2 production technologies of interest for future development in terms of target H2 production rates and lifetimes of sustainable operation.
Green H2 Production by Water Electrolysis Using Cation Exchange Membrane: Insights on Activation and Ohmic Polarization Phenomena
Dec 2021
Publication
Low-temperature electrolysis by using polymer electrolyte membranes (PEM) can play an important role in hydrogen energy transition. This work presents a study on the performance of a proton exchange membrane in the water electrolysis process at room temperature and atmospheric pressure. In the perspective of applications that need a device with small volume and low weight a miniaturized electrolysis cell with a 36 cm2 active area of PEM over a total surface area of 76 cm2 of the device was used. H2 and O2 production rates electrical power energy efficiency Faradaic efficiency and polarization curves were determined for all experiments. The effects of different parameters such as clamping pressure and materials of the electrodes on polarization phenomena were studied. The PEM used was a catalyst-coated membrane (Ir-Pt-Nafion™ 117 CCM). The maximum H2 production was about 0.02 g min−1 with a current density of 1.1 A cm−2 and a current power about 280 W. Clamping pressure and the type of electrode materials strongly influence the activation and ohmic polarization phenomena. High clamping pressure and electrodes in titanium compared to carbon electrodes improve the cell performance and this results in lower ohmic and activation resistances.
Laser Powder Bed Fusion of WE43 in Hydrogen-argon-gas Atmosphere
Sep 2020
Publication
Growing demand for individual and especially complex parts with emphasis on biomedical or lightweight applications enhances the importance of laser powder bed fusion. Magnesium alloys offer both biocompatibility and low density but feature a very high melting point of oxide layers while the evaporation temperature of pure magnesium is much lower. This impedes adequate part quality and process reproducibility. To weaken this oxide layer and enhance processability a 2 %-hydrogen-argon-gas atmosphere was investigated. A machine system was modified to the use of the novel inert gas to determine the influence of gas atmosphere on hollow cuboids and solid cubes. While processing a 20.3 % decrease in structure width and 20.6 % reduction in standard deviation of the cuboids was determined. There was no significate influence on relative density of solid cubes although eight of the ten highest density specimen were fabricated with the hydrogen addition.
Generation of Hydrogen and Oxygen from Water by Solar Energy Conversion
Dec 2021
Publication
Photosynthesis is considered to be one of the promising areas of cheap and environmentally friendly energy. Photosynthesis involves the process of water oxidation with the formation of molecular oxygen and hydrogen as byproducts. The aim of the present article is to review the energy (light) phase of photosynthesis based on the published X-ray studies of photosystems I and II (PS-I and PS-II). Using modern ideas about semiconductors and biological semiconductor structures the mechanisms of H+ O2↑ e− generation from water are described. At the initial stage PS II produces hydrogen peroxide from water as a result of the photoenzymatic reaction which is oxidized in the active center of PS-II on the Mn4CaO5 cluster to form O2↑ H+ e−. Mn4+ is reduced to Mn2+ and then oxidized to Mn4+ with the transfer of reducing the equivalents of PS-I. The electrons formed are transported to PS-I (P 700) where the electrochemical reaction of water decomposition takes place in a two-electrode electrolysis system with the formation of gaseous oxygen and hydrogen. The proposed functioning mechanisms of PS-I and PS-II can be used in the development of environmentally friendly technologies for the production of molecular hydrogen.
Membrane Based Purification of Hydrogen System (MEMPHYS)
Feb 2019
Publication
A hydrogen purification system based on the technology of the electrochemical hydrogen compression and purification is introduced. This system is developed within the scope of the project MEMPHYS. Therefore the project its targets and the different work stages are presented. The technology of the electrochemical purification and the state of the art of hydrogen purification are described. Early measurements in the project have been carried out and the results are shown and discussed. The ability of the technology to recover hydrogen from a gas mixture can be recognized and an outlook into further optimizations shows the future potential. A big advantage is the simultaneous compression of the purified hydrogen up to 200 bar therefore facilitating the transportation and storage.
Methanol Reforming Processes for Fuel Cell Applications
Dec 2021
Publication
Hydrogen production through methanol reforming processes has been stimulated over the years due to increasing interest in fuel cell technology and clean energy production. Among different types of methanol reforming the steam reforming of methanol has attracted great interest as reformate gas stream where high concentration of hydrogen is produced with a negligible amount of carbon monoxide. In this review recent progress of the main reforming processes of methanol towards hydrogen production is summarized. Different catalytic systems are reviewed for the steam reforming of methanol: mainly copper- and group 8–10-based catalysts highlighting the catalytic key properties while the promoting effect of the latter group in copper activity and selectivity is also discussed. The effect of different preparation methods different promoters/stabilizers and the formation mechanism is analyzed. Moreover the integration of methanol steam reforming process and the high temperature–polymer electrolyte membrane fuel cells (HT-PEMFCs) for the development of clean energy production is discussed.
Accelerated Degradation for Solid Oxide Electrolysers: Analysis and Prediction of Performance for Varying Operating Environments
Jan 2022
Publication
Solid oxide electrolysis cells (SOECs) are an efficient technology for the production of green hydrogen that has great potential to contribute to the energy transition and decarbonization of industry. To date however time- and resource-intensive experimental campaigns slow down the development and market penetration of the technology. In order to speed-up the evaluation of SOEC performance and durability accelerated testing protocols are required. This work provides the results of experimental studies on the performance of a SOEC stack operated under accelerated degradation conditions. In order to initiate and accelerate degradation experiments were performed with high steam partial pressures at the gas inlet higher voltages and lower temperatures and high steam conversion rates. Thereby different types and degrees of impact on performance were observed which were analyzed in detail and linked to the underlying processes and degradation mechanisms. In this context significantly higher degradation rates were found compared to operation under moderate operating conditions with the different operating strategies varying in their degradation acceleration potential. The results also suggest that a few hundred hours of operation may be sufficient to predict long-term performance with the proposed operating strategies providing a solid basis for accelerated assessment of SOEC performance evolution and lifetime.
Mechanism of Action of Polytetrafluoroethylene Binder on the Performance and Durability of High-temperature Polymer Electrolyte Fuel Cells
Feb 2021
Publication
In this work new insights into impacts of the polytetrafluoroethylene (PTFE) binder on high temperature polymer electrolyte fuel cells (HT-PEFCs) are provided by means of various characterizations and accelerated stress tests. Cathodes with PTFE contents from 0 wt% to 60 wt% were fabricated and compared using electrochemical measurements. The results indicate that the cell with 10 wt% PTFE in the cathode catalyst layer (CCL) shows the best performance due to having the lowest mass transport resistance and cathode protonic resistance. Moreover cyclic voltammograms show that Pt (100) edge and corner sites are significantly covered by PTFE and phosphate anions when the PTFE content is higher than 25 wt%. Open-circuit and low load-cycling conditions are applied to accelerate degradation processes of the HT-PEFCs. The PTFE binder shows a network structure in the pores of the catalyst layer which reduces phosphoric acid leaching during the aging tests. In addition the high binder HT-PEFCs more easily suffer from a mass transport problem leading to more severe performance degradation.
A Thorough Economic Evaluation by Implementing Solar/Wind Energies for Hydrogen Production: A Case Study
Jan 2022
Publication
A technical–economic assessment was carried out in this study to determine the possibilities for wind and solar power generation in Afghanistan’s Helmand province. The results showed that most of the province has a solar irradiance of over 400 W/m2 and also showed that wind and solar power generated in the province can be up to twice as cheap as the official price of renewable power in Afghanistan. The most suitable site for solar and hydrogen production was found to be Laškar Gah where solar and hydrogen can be produced at a cost of 0.066 $/kWh and 2.1496 $/kg-H ¯ 2 respectively. In terms of wind power production and hydrogen production from wind the most suitable site was Sang¯ın where wind power and hydrogen could be produced at costs of 0.057 $/kWh and 1.4527 $/kg-H2 respectively. Despite the high potential of wind and solar energy in the Helmand province the most suitable place in this region to produce hydrogen from wind/solar energy was evaluated from technical economic and environmental perspectives with the Multi-Criteria DecisionMaking (MCDM) method. The Stepwise Weight Assessment Ratio Analysis (SWARA) method was used for weighting criteria and the Weighted Aggregated Sum Product Assessment (WASPAS) method was used to prioritize locations. The results show that Sang¯ın is the most suitable place for the construction of a wind hydrogen power plant and Laškar Gah is the most suitable place for the ¯ construction of a solar hydrogen power plant.
Aldehyde Replacement Advances Efficient Hydrogen Production in Electrolyser
Mar 2022
Publication
The high energy consumption and production of undesired oxygen greatly restrict the wide adoption of water electrolysis for hydrogen production. In a paper recently published in Nature Catalysis Wang and coworkers rationally introduce aldehydes for oxidation at anode to replace oxygen evolution reaction which can produce hydrogen and value-added products at low potential realizing efficient bipolar hydrogen production with high-purity. Moreover these aldehydes are biomass-derived and contribute to sustainable hydrogen production
The Role of Effectiveness Factor on the Modeling of Methanol Steam Reforming Over CuO/ZnO/Al2O3 Catalyst in a Multi-tubular Reactor
Jan 2022
Publication
A pseudo-homogeneous model for the methanol steam reforming process was developed based on reaction kinetics over a CuO/ZnO/Al2O3 catalyst and non-adiabatic heat and mass transfer performances in a co-current packed-bed reactor. A Thiele modulus method and an intraparticle distribution method were applied for predicting the effectiveness factors for main reactions and providing insights into the diffusion-reaction process in a cylindrical catalyst pellet. The results of both methods are validated and show good agreements with the experimental data but the intraparticle distribution method provides better predictions. Results indicate that increases in catalyst size and bulk fluid temperature amplify the impact of intraparticle diffusion limitations showing a decrease in effectiveness factors. To satisfy the requirements of a high temperature polymer electrolyte membrane fuel cell stack the optimized operating conditions which bring the methanol and CO concentrations to less than 1% vol in the reformate stream are determined based on the simulation results.
Data-driven Parameterization of Polymer Electrolyte Membrane fuel Cell Models Via Simultaneous Local Linear Structured State Space Identification
Feb 2021
Publication
In order to mitigate the degradation and prolong the lifetime of polymer electrolyte membrane fuel cells advanced model-based control strategies are becoming indispensable. Thereby the availability of accurate yet computationally efficient fuel cell models is of crucial importance. Associated with this is the need to efficiently parameterize a given model to a concise and cost-effective experimental data set. A challenging task due to the large number of unknown parameters and the resulting complex optimization problem. In this work a parameterization scheme based on the simultaneous estimation of multiple structured state space models obtained by analytic linearization of a candidate fuel cell stack model is proposed. These local linear models have the advantage of high computational efficiency regaining the desired flexibility required for the typically iterative task of model parameterization. Due to the analytic derivation of the local linear models the relation to the original parameters of the non-linear model is retained. Furthermore the local linear models enable a straight-forward parameter significance and identifiability analysis with respect to experimental data. The proposed method is demonstrated using experimental data from a 30 kW commercial polymer electrolyte membrane fuel cell stack.
A Comparative Technoeconomic Analysis of Renewable Hydrogen Production Using Solar Energy
May 2016
Publication
A technoeconomic analysis of photoelectrochemical (PEC) and photovoltaic-electrolytic (PV-E) solar-hydrogen production of 10 000 kg H2 day−1 (3.65 kilotons per year) was performed to assess the economics of each technology and to provide a basis for comparison between these technologies as well as within the broader energy landscape. Two PEC systems differentiated primarily by the extent of solar concentration (unconcentrated and 10× concentrated) and two PV-E systems differentiated by the degree of grid connectivity (unconnected and grid supplemented) were analyzed. In each case a base-case system that used established designs and materials was compared to prospective systems that might be envisioned and developed in the future with the goal of achieving substantially lower overall system costs. With identical overall plant efficiencies of 9.8% the unconcentrated PEC and non-grid connected PV-E system base-case capital expenses for the rated capacity of 3.65 kilotons H2 per year were $205 MM ($293 per m2 of solar collection area (mS−2) $14.7 WH2P−1) and $260 MM ($371 mS−2 $18.8 WH2P−1) respectively. The untaxed plant-gate levelized costs for the hydrogen product (LCH) were $11.4 kg−1 and $12.1 kg−1 for the base-case PEC and PV-E systems respectively. The 10× concentrated PEC base-case system capital cost was $160 MM ($428 mS−2 $11.5 WH2P−1) and for an efficiency of 20% the LCH was $9.2 kg−1. Likewise the grid supplemented base-case PV-E system capital cost was $66 MM ($441 mS−2 $11.5 WH2P−1) and with solar-to-hydrogen and grid electrolysis system efficiencies of 9.8% and 61% respectively the LCH was $6.1 kg−1. As a benchmark a proton-exchange membrane (PEM) based grid-connected electrolysis system was analyzed. Assuming a system efficiency of 61% and a grid electricity cost of $0.07 kWh−1 the LCH was $5.5 kg−1. A sensitivity analysis indicated that relative to the base-case increases in the system efficiency could effect the greatest cost reductions for all systems due to the areal dependencies of many of the components. The balance-of-systems (BoS) costs were the largest factor in differentiating the PEC and PV-E systems. No single or combination of technical advancements based on currently demonstrated technology can provide sufficient cost reductions to allow solar hydrogen to directly compete on a levelized cost basis with hydrogen produced from fossil energy. Specifically a cost of CO2 greater than ∼$800 (ton CO2)−1 was estimated to be necessary for base-case PEC hydrogen to reach price parity with hydrogen derived from steam reforming of methane priced at $12 GJ−1 ($1.39 (kg H2)−1). A comparison with low CO2 and CO2-neutral energy sources indicated that base-case PEC hydrogen is not currently cost-competitive with electrolysis using electricity supplied by nuclear power or from fossil-fuels in conjunction with carbon capture and storage. Solar electricity production and storage using either batteries or PEC hydrogen technologies are currently an order of magnitude greater in cost than electricity prices with no clear advantage to either battery or hydrogen storage as of yet. Significant advances in PEC technology performance and system cost reductions are necessary to enable cost-effective PEC-derived solar hydrogen for use in scalable grid-storage applications as well as for use as a chemical feedstock precursor to CO2-neutral high energy-density transportation fuels. Hence such applications are an opportunity for foundational research to contribute to the development of disruptive approaches to solar fuels generation systems that can offer higher performance at much lower cost than is provided by current embodiments of solar fuels generators. Efforts to directly reduce CO2 photoelectrochemically or electrochemically could potentially produce products with higher value than hydrogen but many as yet unmet challenges include catalytic efficiency and selectivity and CO2 mass transport rates and feedstock cost. Major breakthroughs are required to obtain viable economic costs for solar hydrogen production but the barriers to achieve cost-competitiveness with existing large-scale thermochemical processes for CO2 reduction are even greater.
No more items...