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Review of IGEM/SR/25 for Use with Hydrogen
Jan 2021
Publication
This report presents the findings of the initial gap analysis and technical review of IGEM/SR/25 undertaken as a collaborative effort between HSE and DNV GL. The review is intended to help understand the steps which would be involved in updating the standard to include data appropriate for installations using H2 or an H2/NG blend. Furthermore the report highlights where additional research and updated data applicable to H2 installations is needed to enable development of an H2-specific supplement to the standard.<br/>A review of alternative approaches for area classification is presented. This review is aimed at determining whether existing standards or guidance provide methodologies which could be used as an alternative to IGEM/SR/25 for area classification of systems using either H2 or H2/NG blends. The review covers IGEM/SR/25 IGE/SR/23 EI15 BCGA guidance BS EN 60079:10:1 (including Quadvent) NFPA 497 API RP 505 and EIGA Doc. 121/14. Some of these are general like the British Standard BS EN 60079-10-1:2015 while others are industry specific like IGEM/SR/25 and EI15.<br/>Consideration is given to the methodology that each area classification approach presents for establishing the zone and zone size with particular focus on how factors such as ventilation and gas buoyancy are accounted for in the methods. The findings of the review indicate that none of the alternative approaches evaluated in the study provide an approach that is suitable for the gas industry for the area classification of gas network installations involving H2 or an H2/NG blend.
Dynamic Mechanical Fatigue Behavior of Polymer Electrolyte Membranes for Fuel Cell Electric Vehicles Using a Gas Pressure-Loaded Blister
Nov 2021
Publication
This study reports on an innovative press-loaded blister hybrid system equipped with gas-chromatography (PBS-GC) that is designed to evaluate the mechanical fatigue of two representative types of commercial Nafion membranes under relevant PEMFC operating conditions (e.g. simultaneously controlling temperature and humidity). The influences of various applied pressures (50 kPa 100 kPa etc.) and blistering gas types (hydrogen oxygen etc.) on the mechanical resistance loss are systematically investigated. The results evidently indicate that hydrogen gas is a more effective blistering gas for inducing dynamic mechanical losses of PEM. The changes in proton conductivity are also measured before and after hydrogen gas pressure-loaded blistering. After performing the mechanical aging test a decrease in proton conductivity was confirmed which was also interpreted using small angle X-ray scattering (SAXS) analysis. Finally an accelerated dynamic mechanical aging test is performed using the homemade PBS-GC system where the hydrogen permeability rate increases significantly when the membrane is pressure-loaded blistering for 10 min suggesting notable mechanical fatigue of the PEM. In summary this PBS-GC system developed in-house clearly demonstrates its capability of screening and characterizing various membrane candidates in a relatively short period of time (<1.5 h at 50 kPa versus 200 h).
Simulation of Hydrogen Mixing and Par Operation During Accidental Release in an LH2 Carrier Engine Room
Sep 2021
Publication
Next-generation LH2 carriers may use the boil-off gas from the cargo tanks as additional fuel for the engine. As a consequence hydrogen pipes will enter the room of the ship’s propulsion system and transport hydrogen to the main engine. The hydrogen distribution resulting from a postulated hydrogen leak inside the room of the propulsion system has been analyzed by means of Computational Fluid Dynamics (CFD). In a subsequent step simulations with passive auto-catalytic recombiners (PARs) were carried out in order to investigate if the recombiners can increase the safety margins during such accident scenarios. CFD enables a 3D prediction of the transient distribution with a high resolution allowing to identify local accumulation of hydrogen and consequently to identify optimal PAR positions as well as to demonstrate the efficiency of the PARs. The simulation of the unmitigated reference case reveals a strong natural circulation driven by the density difference of hydrogen and the incoming cold air from the ventilation system. Globally this natural circulation dilutes the hydrogen and removes a considerable amount from the room of the ship’s propulsion system via the ventilation ducts. However a hydrogen accumulation beyond the flammability limit is identified below the first ceiling above the leak position and the back-side wall of the engine room. Based on these findings suitable positions for recombiners were identified. The design objectives of the PAR system were on the one hand to provide both high instantaneous and integral removal rate and on the other hand to limit build-up of flammable clouds by means of depletion and PAR induced mixing processes. The simulations performed with three different PAR arrangements (variation of large and<br/>small PAR units at different positions) confirm that the PARs reduce efficiently the hydrogen<br/>accumulations.
Synthesis and Characterization of Biogenic Iron Oxides of Different Nanomorphologies from Pomegranate Peels for Efficient Solar Hydrogen Production
Feb 2020
Publication
An eco-friendly green synthesis of mesoporous iron oxide (hematite) using pomegranate peels through a low-cost and massive product method was investigated. The mass of pomegranate peels was varied to control the morphology of the produced hematite (Fe2O3). The structures textures and optical properties of the products were investigated by FTIR XRD FE-SEM and UV–Vis spectroscopy. Three different Fe2O3 morphologies were obtained; Fe2O3(I) nanorod like shape Fe2O3(II) nanoparticles and Fe2O3(III) nanoporous structured layer. The bandgap values for Fe2O3 (I) (II) and (III) were 2.71 2.95 and 2.29 eV respectively. The newly hematite samples were used as promising photoelectrodes supported on graphite substrate for the photoelectrochemical (PEC) water splitting toward the efficient production of solar hydrogen. The number of generated hydrogen moles was calculated per active area to be 50 molh−1 cm−2 for electrode III which decreased to 15.3molh−1 cm−2 for electrode II. The effects of temperature (30–70 ◦C) on the PEC behavior of the three electrodes were addressed. Different thermodynamic parameters were calculated for the three electrodes which showed activation energies of 13.4 16.8 and 15.2 kJmol−1 respectively. The electrode stability was addressed as a function of the number of runs and exposure time in addition to electrochemical impedance study. Finally the conversion efficiency of the incident photon to-current(IPCE) was estimated under the monochromatic illumination. The optimum value was ∼11% @ 390nm for Fe2O3(III) electrode
Greedy Energy Management Strategy and Sizing Method for a Stand-alone Microgrid with Hydrogen Storage
Nov 2021
Publication
This paper presents a greedy energy management strategy based on model predictive control (MPC) for a stand-alone microgrid powered by photovoltaic (PV) arrays and equipped with batteries and a power-to-hydrogen-to-power (P2H2P) system. The proposed strategy consists of a day-ahead plan and an intra-day dispatch method. In the planning stage the sequence of plan is to determine the power of each storage device for a certain period which is initially generated under the principle that PV arrays have the highest priority followed by the batteries and finally the P2H2P system using short-term forecast data of both load and solar irradiance. The initial plan can be optimized with objectives of harvesting more PV generation in storage and minimizing unmet load through rescheduling P2H2P system and batteries. Three parameters including reserved capacity of batteries predischarge coefficient of fuel cell (FC) and greedy coefficient of electrolyzer (EL) are introduced during plan optimization process to enhance the robustness against forecast errors. In the dispatching stage the energy dispatch is subject to the scheduled plan and the operational constraints. To demonstrate the capabilities of the proposed strategy a case study is performed for a hotel with a mean power consumption of 1567 kWh/day based on the system configuration optimized by HOMER software in comparison with the load following (LF) strategy and the global optimum solution solved by mixed integer linear programing (MILP). The simulation results show that the annual unmet load using the proposed strategy is reduced from 13434 kWh to 2370 kWh which is 528 kWh lower than the optimum solution. Meanwhile the cost of energy (COE) of the proposed strategy decreases by US$ 0.08/kWh compared to the LF strategy and is equal to the optimum solution. Finally the performance of configuration optimization employing genetic algorithm (GA) under different energy management strategies is investigated with the objective function of minimizing the net present cost (NPC). Furthermore the robustness of the proposed strategy is studied. The results show that the proposed strategy gives an NPC and COE of US$ 2.4 million (Mn) and US$ 0.43/kWh which are 23.4% and 9.7% lower than those of systems utilizing the SoC-based strategy and the LF strategy respectively. The results also demonstrate that the strategy is robust against forecast errors especially for overestimated forecast models.
Solid Oxide Fuel Cell-Based Polygeneration Systems in Residential Applications: A Review of Technology, Energy Planning and Guidelines for Optimizing the Design
Oct 2022
Publication
Solid oxide fuel cells are an emerging energy conversion technology suitable for high-temperature power generation with proper auxiliary heat. Combining SOFCs and polygeneration has produced practical applications for modern energy system designs. Even though many researchers have reviewed these systems’ technologies opportunities and challenges reviews regarding the optimal strategy for designing and operating the systems are limited. Polygeneration is more complicated than any other energy generation type due to its ability to generate many types of energy from various prime movers. Moreover integration with other applications such as vehicle charging and fueling stations increases the complication in making the system optimally serve the loads. This study elaborates on the energy planning and guidelines for designing a polygeneration system especially for residential applications. The review of polygeneration technologies also aligns with the current research trend of developing green technology for modern and smart homes in residential areas. The proposed guideline is expected to solve the complication in other applications and technologies and design the polygeneration system optimally.
The Role of Hydrogen in the Optimal Design of Off-grid Hybrid Renewable Energy Systems
Jan 2022
Publication
The optimal design of off-grid hybrid renewable energy systems (HRESs) is a challenging task which often involves conflicting goals to be faced. In this work levelized cost of energy (LCOE) and CO2 emissions have been addressed simultaneously by using the ε-constraint method together with the particle swarm optimization (PSO) algorithm. Cost-emissions Pareto fronts of different HRES configurations were developed to gain greater awareness about the potential of renewable-based energy systems in off-grid applications. Various combinations of the following components were investigated: photovoltaic panels wind turbines batteries hydrogen and diesel generators. The hydrogen-based system comprises an electrolyzer to convert the excess renewable energy into hydrogen a pressurized tank for H2 storage and a fuel cell for the reconversion of hydrogen into electricity during renewable energy deficits. Electrolyzer and fuel cell devices were modelled by means of part-load performance curves. Size-dependent costs and component lifetimes as a function of the cumulative operational duty were also considered for a more accurate techno-economic assessment. The proposed methodology was applied to the Froan islands (Norway) which were chosen as a reference case study since they are well representative of many other insular microgrid environments in Northern Europe. Results from the sizing simulations revealed that energy storage devices are key components to reduce the dependency on fossil fuels. In particular the hydrogen storage system is crucial in off-grid areas to enhance the RES penetration and avoid a sharp increase in the cost of energy. Hydrogen in fact allows the battery and RES technologies not to be oversized thanks to its cost-effective long-term storage capability. Concerning the extreme case with no diesel the cheapest configuration which includes both batteries and hydrogen has an LCOE of 0.41 €/kWh. This value is around 35% lower than the LCOE of a system with only batteries as energy storage.
Waste Aluminum Application as Energy Valorization for Hydrogen Fuel Cells for Mobile Low Power Machines Applications
Nov 2021
Publication
This article proposes a new model of power supply for mobile low power machines applications between 10 W and 30 W such as radio-controlled (RC) electric cars. This power supply is based on general hydrogen from residual aluminum and water with NaOH so it is proposed energy valorization of aluminum waste. In the present research a theoretical model allows us to predict the requested aluminum surface and the required flow of hydrogen has been developed also considering in addition to the geometry and purity of the material two key variables as the temperature and the molarity of the alkaline solution used in the hydrogen production process. Focusing on hydrogen production isopropyl alcohol plays a key role in the reactor’s fuel cell vehicle as it filters out NaOH particles and maintains a constant flow of hydrogen for the operation of the machine keeping the reactor temperature controlled. Finally a comparison of the theoretical and experimental data has been used to validate the developed model using aluminum sheets from ring cans to generate hydrogen which will be used as a source of hydrogen in a power fuel cell of an RC car. Finally the manuscript shows the parts of the vehicle’s powertrain its behavior and mode of operation.
Research on the Hydrogen Consumption of Fuel Cell Electric Vehicles Based on the Flowmeter and Short-cut Method
Sep 2022
Publication
Energy consumption is essential for evaluating the competitiveness of fuel cell electric vehicles. A critical step in energy consumption measurement is measuring hydrogen consumption including the mass method the P/T method and the flowmeter method. The flowmeter method has always been a research focus because of its simple operation low cost and solid real-time performance. Current research has shown the accuracy of the flowmeter method under specific conditions. However many factors in the real scenario will influence the test result such as unintended vibration environment temperature and onboard hydrogen capacity calibration. On the other hand the short-cut method is also researched to replace the run-out method to improve test efficiency. To evaluate whether the flowmeter method basing on the short-cut method can genuinely reflect the hydrogen consumption of an actual vehicle we research and test for New European Driving Cycle (NEDC) and China Light-Duty Vehicle Test Cycle (CLTC) using the same vehicle. The results show that the short-cut method can save at least 50% of the test time compared with the run-out method. The error of the short-cut method based on the flowmeter for the NEDC working condition is less than 0.1% and for the CLTC working conditions is 8.12%. After adding a throttle valve and a 4L buffer tank the error is reduced to 4.76% from 8.12%. The test results show that hydrogen consumption measurement based on the flowmeter and short-cut method should adopt corresponding solutions according to the scenarios.
Towards a Climate-neutral Energy System in the Netherlands
Jan 2022
Publication
This paper presents two different scenarios for the energy system of the Netherlands that achieve the Dutch government’s national target of near net-zero greenhouse gas emissions in 2050. Using the system optimisation model OPERA the authors have analysed the technology sector and cost implications of the assumptions underlying these scenarios. While the roles of a number of key energy technology and emission mitigation options are strongly dependent on the scenario and cost assumptions the analysis yields several common elements that appear in both scenarios and that consistently appear under differing cost assumptions. For example one of the main options for the decarbonisation of the Dutch energy system is electrification of energy use in end-use sectors and for the production of renewable hydrogen with electrolysers. As a result the level of electricity generation in 2050 will be three to four times higher than present generation levels. Ultimately renewable energy – particularly from wind turbines and solar panels – is projected to account for the vast majority of electricity generation around 99% in 2050. Imbalances between supply and demand resulting from this variable renewable electricity production can be managed via flexibility options including demand response and energy storage. Hydrogen also becomes an important energy carrier notably for transportation and in industry. If import prices are lower than costs of domestic production from natural gas with CCS or through electrolysis from renewable electricity (2.4–2.7 €/kgH2) the use of hydrogen increases especially in the built environment.
Uncertainty of Acceleration of a Premixed Laminar Unstable Hydrogen Flame
Sep 2021
Publication
Unstable hydrogen-air flame behavior randomities are important for industrial safety hydrogen infrastructure safety and nuclear power plant hydrogen safety problems. The paper is devoted to an experimental and theoretical study of the uncertainty in the acceleration of a premixed laminar unstable hydrogen flame. The results of experiments on spherical flame propagation in hydrogen-air mixtures with a hydrogen content of 10 to 60% are presented. The experiments were repeated up to 30 times in the same mixtures. A statistical analysis of the experimental results has been carried out. The scatter of the experimental data depending on the hydrogen content in the mixture was estimated. It was found to be between 8 to 17% for different mixtures with the same flame radius and mixture composition. Similar results were obtained using the numerical integration of the Sivashinsky equation of flame propagation.
A Comprehensive Evaluation of a Novel Integrated System Consisting of Hydrogen Boil-off Gas Reliquifying Process and Polymer Exchange Membrane Fuel Cell Using Exergoeconomic and Markov Analyses
Dec 2021
Publication
The price of constructing hydrogen generation units is very high and sometimes it is not possible to build them in the desired location so the transfer of hydrogen from the hydrogen generation system to the units that need it is justified. Since the storage of hydrogen gas needs a large volume and its transportation is very complex so if hydrogen is stored in liquid form this problem can be resolved. In transporting liquid hydrogen (LH2) over long distances owing to heat transfer to the environment the LH2 vaporizes forming boil-off gas (BOG). Herein in lieu of only reliquifying the BOG this study proposes and assesses a system employing the BOG partially as feed for a novel liquefaction process and also the remaining utilized in a proton exchange membrane fuel cell (PEMFC) to generate power. Using the cold energy of the onsite liquid oxygen utility of the LH2 cargo vessel the mixed refrigerant liquefaction cycle is further cooled down. In this regard by using 130 kg/h BOG as input 60.37 kg/h of liquid hydrogen is produced and the rest enters PEMFC with 552.7 kg/h oxygen to produce 1592 kW of power. The total thermal efficiency of the integrated system and electrical efficiency of the PEMFC is 83.18% and 68.76% respectively. Regarding the liquefaction cycle its specific power consumption (SPC) and coefficient of performance (COP) were achieved at 3.203 kWh/kgLH2 and 0.1876 respectively. The results of exergy analysis show that the exergy destruction of the whole system is 937.4 kW and also its exergy efficiency is calculated to be 58.38%. Exergoeconomic and Markov analyses have also been applied to the integrated system. Also by changing the important parameters of PEMFC its optimal performance has been extracted.
Few-atom Cluster Model Systems for a Hydrogen Economy
Apr 2020
Publication
To increase the share of renewable zero-emission energy sources such as wind and solar power in our energy supply the problem of their intermittency needs to be addressed. One way to do so is by buffering excess renewable energy via the production of hydrogen which can be stored for later use after re-electrification. Such a clean renewable energy cycle based on hydrogen is commonly referred to as the hydrogen economy. This review deals with cluster model systems of the three main components of the hydrogen economy i.e. hydrogen generation hydrogen storage and hydrogen re-electrification and their basic physical principles. We then present examples of contemporary research on few atom clusters both in the gas phase and deposited to show that by studying these clusters as simplified models a mechanistic understanding of the underlying physical and chemical processes can be obtained. Such an understanding will inspire and enable the design of novel materials needed for advancing the hydrogen economy.
Calculation and Analysis of Efficiencies and Annual Performances of Power-to-Gas Systems
Mar 2017
Publication
This paper describes a generic and systematic method to calculate the efficiency and the annual performance for Power-to-Gas (PtG) systems. This approach gives the basis to analytically compare different PtG systems using different technologies under different boundary conditions. To have a comparable basis for efficiency calculations a structured break down of the PtG system is done. Until now there has not been a universal approach for efficiency calculations. This has resulted in a wide variety of efficiency calculations used in feasibility studies and for business-case calculations. For this the PtG system is divided in two sub-systems: the electrolysis and the methanation. Each of the two sub-systems consists of several subsystem boundary levels. Staring from the main unit i.e. the electrolysis stack and/or methanation reactor further units that are required to operate complete PtG system are considered with their respective subsystem boundary conditions. The paper provides formulas how the efficiency of each level can be calculated and how efficiency deviations can be integrated which are caused by the extended energy flow calculations to and from energy users and thermal losses. By this a sensitivity analysis of the sub-systems can be gained and comprehensive goal functions for optimizations can be defined. In a second step the annual performance of the system is calculated as the ratio of useable output and energetic input over one year. The input is the integral of the annual need of electrical and thermal energy of a PtG system depending on the different operation states of the plant. The output is the higher heating value of the produced gas and – if applicable – heat flows that are used externally. The annual performance not only evaluates the steady-state operating efficiency under full load but also other states of the system such as cold standby or service intervals. It is shown that for a full system operation assessment and further system concept development the annual performance is of much higher importance than the steady-state system efficiency which is usually referred to. In a final step load profiles are defined and the annual performance is calculated for a specific system configuration. Using this example different operation strategies are compared.
Law and Policy Review on Green Hydrogen Potential in ECOWAS Countries
Mar 2022
Publication
This paper aims to review existing energy-sector and hydrogen-energy-related legal policy and strategy documents in the ECOWAS region. To achieve this aim current renewable-energyrelated laws acts of parliament executive orders presidential decrees administrative orders and memoranda were analyzed. The study shows that ECOWAS countries have strived to design consistent legal instruments regarding renewable energy in developing comprehensive legislation and bylaws to consolidate it and to encourage investments in renewable energy. Despite all these countries having a legislative basis for regulating renewable energy there are still weaknesses that revolve around the law and policy regarding its possible application in green hydrogen production and use. The central conclusion of this review paper is that ECOWAS member states presently have no official hydrogen policies nor bylaws in place. The hydrogen rise presents a challenge and opportunity for members to play an important role in the fast-growing global hydrogen market. Therefore these countries need to reform their regulatory frameworks and align their policies by introducing green hydrogen production in order to accomplish their green economy transition for the future and to boost the continent’s sustainable development.
Gas Goes Green: Britain's Hydrogen Blending Delivery Plan
Jan 2022
Publication
Britain’s Hydrogen Blending Delivery Plan which sets out how all five of Britain’s gas grid companies will meet the Government’s target for Britain’s network of gas pipes to be ready to deliver 20% hydrogen to homes and businesses from 2023 as a replacement for natural gas.
Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies
Jul 2020
Publication
The economic and ecological production of green hydrogen by water electrolysis is one of the major challenges within Carbon2Chem and other power-to-X projects. This paper presents an evaluation of the different water electrolysis technologies with respect to their specific energy demand carbon footprint and the forecast production costs in 2030. From a current perspective alkaline water electrolysis is evaluated as the most favorable technology for the cost-effective production of low-carbon hydrogen with fluctuating renewables.
Techno-economic Assessment of Electrolytic Hydrogen in China Considering Wind-solar-load Characteristic
Jan 2023
Publication
Hydrogen production by electrolysis is considered an essential means of consuming renewable energy in the future. However the current assessment of the potential of renewable energy electrolysis for hydrogen production is relatively simple and the perspective is not comprehensive. Here we established a Combined Wind and Solar Electrolytic Hydrogen system considering the influence of regional wind-solar-load characteristics and transmission costs to evaluate the hydrogen production potential of 31 provincial-level regions in China in 2050. The results show that in 2050 the levelized cost of hydrogen (LCOH) in China’s provincial regions will still be higher than 10 ¥/kg which is not cost-competitive compared to the current hydrogen production from fossil fuels. It is more cost-effective to deploy wind turbines than photovoltaic in areas with similar wind and solar resources or rich in wind resources. Wind-solar differences impact LCOH equipment capacity configuration and transmission cost composition while load fluctuation significantly impacts LCOH and electricity storage configuration. In addition the sensitivity analysis of 11 technical and economic parameters showed differences in the response performance of LCOH changes to different parameters and the electrolyzer conversion efficiency had the most severe impact. The analysis of subsidy policy shows that for most regions (except Chongqing and Xizang) subsidizing the unit investment cost of wind turbines can minimize LCOH. Nevertheless from the perspective of comprehensive subsidy effect subsidy cost and hydrogen energy development it is more cost-effective to take subsidies for electrolysis equipment with the popularization of hydrogen
Life Cycle Assessment of Carbon Footprint in Public Transportation - A Case Study of Bus Route NO. 2 in Tainan City, Taiwan
Apr 2019
Publication
Human activities have exacerbated global greenhouse effects resulting in extreme climate changes that have caused disasters and food and water shortages in recent years. Transport activities are the one of the main causes of global greenhouse gas (GHG) emissions. Therefore policy makers must develop some strategies to reduce GHG emissions. One of the Taiwan’s transportation policies intended to reduce CO2 emissions is to replace all traditional diesel fuel urban buses with alternative energy buses. This paper uses a case study of bus route NO. 2 in Tainan City and follows the international standard ISO/TS 14067 and PAS2050 to measure the carbon footprints of different energy buses. The purpose is to measure the environmental benefits of alternative energy buses. The results of the bus carbon footprints from high to low were LNG buses 63.14g CO2e/pkm; traditional diesel buses 54.6g CO2e/pkm; liquefied petroleum gas buses 47.4g CO2e/pkm; plug-in electric buses 37.82g CO2e/pkm and hydrogen fuel cell bus es 29.17g CO2e/pkm respectively. It was also found that the use of hydrogen fuel cell buses would potentially reduce CO2e emissions in Tainan City by 1244081 tons which at this time is only city bus No. 2. If all the Taiwan city buses were switched to hydrogen fuel cell buses this would potentially reduce CO2e by 227832.39 tons. The effect of the reduction in carbon emissions from the use of hydrogen fuel cells buses in all Taiwanese urban areas is the equivalent of planting 22.78 million trees. It is thus suggested that the government use hydrogen fuel cell buses as the future of the country’s major alternative energy buses since they are the most environmentally friendly alternative to reducing CO2 emissions.
HydroGenerally - Episode 3: Lift Off for Hydrogen in Aviation
Apr 2022
Publication
In this third episode Steffan Eldred and Hannah Abson from Innovate UK KTN are exploring the scale of the opportunity that hydrogen and aviation present alongside their special guest Katy Milne Head of Industrial Strategy at FlyZero.
The podcast can be found on their website
The podcast can be found on their website
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