Production & Supply Chain
Electrolyzer Array Alternate Control Strategy Considering Wind Power Prediction
Aug 2022
Publication
Non grid connected wind power hydrogen production technology is of great significance for the large-scale comprehensive utilization of hydrogen energy and accelerating the development of clean energy. In this paper an electrolyzer power allocation and alternate control method for non grid connected wind power hydrogen production is proposed and the optimized control strategy are combined to predict the maximum wind power of certain time interval. While retaining the required data characteristics the instantaneous fluctuation of some wind power data is eliminated which provides a reliable basis for power distribution in the alternation control strategy of electrolyzer array. The case simulation verifies the effectiveness of the electrolyzer array control principle and the prediction of the maximum wind power. While ensuring the absorption effect and hydrogen production rate the service life and operation safety of the electrolyzer array are effectively improved by balancing the working state of each electrolyzer.
A Simulation Study on Evaluating the Influence of Impurities on Hydrogen Production in Geological Carbon Dioxide Storage
Sep 2023
Publication
In this study we examined the effect of CO2 injection into deep saline aquifers considering impurities present in blue hydrogen production. A fluid model was designed for reservoir conditions with impurity concentrations of 3.5 and 20%. The results showed that methane caused density decreases of 95.16 and 76.16% at 3.5 and 20% respectively whereas H2S caused decreases of 99.56 and 98.77% respectively. Viscosity decreased from 0.045 to 0.037 cp with increasing methane content up to 20%; however H2S did not affect the viscosity. Notably CO2 with H2S impacted these properties less than methane. Our simulation model was based on the Gorae-V properties and simulated injections for 10 years followed by 100 years of monitoring. Compared with the pure CO2 injection methane reached its maximum pressure after eight years and eleven months at 3.5% and eight years at 20% whereas H2S reached maximum pressure after nine years and two months and nine years and six months respectively. These timings affected the amount of CO2 injected. With methane as an impurity injection efficiency decreased up to 73.16% whereas with H2S it decreased up to 81.99% with increasing impurity concentration. The efficiency of CO2 storage in the dissolution and residual traps was analyzed to examine the impact of impurities. The residual trap efficiency consistently decreased with methane but increased with H2S. At 20% concentration the methane trap exhibited higher efficiency at the end of injection; however H2S had a higher efficiency at the monitoring endpoint. In carbon capture and storage projects methane impurities require removal whereas H2S may not necessitate desulfurization due to its minimal impact on CO2 storage efficiency. Thus the application of carbon capture and storage (CCS) to CO2 emissions containing H2S as an impurity may enable economically viable operations by reducing additional costs.
Open-source Project Feasibility Tools for Supporting Development of the Green Ammonia Value Chain
Nov 2022
Publication
Ammonia plays a vital role in feeding the world through fertilizer production as well as having other industrial uses. However current ammonia production processes rely heavily on fossil fuels mostly natural gas to generate hydrogen as a feedstock. There is an urgent need to re-design and decarbonise the production process to reduce greenhouse emissions and avoid dependence on volatile gas markets and a depleting resource base. Renewable energy driven electrolysis to generate hydrogen provides a viable pathway for producing carbon-free or green ammonia. However a key challenge associated with producing green ammonia is managing low cost but highly variable wind and solar renewable energy generation for hydrogen electrolysis while maintaining reliable operation of the less flexible ammonia synthesis unit. To date green ammonia production has only been demonstrated at pilot scale and optimising plant configurations and scaling up production facilities is an urgent task. Existing feasibility studies have demonstrated the ability to model and cost green ammonia production pathways that can overcome the technical and economic challenges. However these existing approaches are context specific demonstrating the ability to model and cost green ammonia production for defined locations with set configurations. In this paper we present a modelling framework that consolidates the array of configurations previously studied into a single framework that can be tailored to the location of interest. Our open-source green ammonia modelling and costing tool dynamically simulates the integration of renewable energy with a wide range of balancing power and storage options to meet the flexible demands of the green ammonia production process at hourly time resolution over a year or more. Unlike existing models the open-source implementation of our tool allows it to be used by a potentially wide range of stakeholders to explore their own projects and help guide the upscaling of green ammonia as a pathway for decarbonisation. Using Gladstone in Australia as a case study a 1 million tonne per annum (MMTPA) green ammonia plant is modelled and costed using price assumptions for major equipment in 2030 provided by the Australian Energy Market Operator (AEMO). Using a hybrid (solar PV and wind) renewable energy source and Battery Energy Storage System as balancing technology we estimate a levelized cost of ammonia (LCOA) between 0.69 and 0.92 USD kgNH3 -1 . While greater than historical ammonia production costs from natural gas falling renewables costs and emission reduction imperatives suggest a major future role for green ammonia.
Green Hydrogen Production through Ammonia Decomposition Using Non-Thermal Plasma
Sep 2023
Publication
Liquid hydrogen carriers will soon play a significant role in transporting energy. The key factors that are considered when assessing the applicability of ammonia cracking in large-scale projects are as follows: high energy density easy storage and distribution the simplicity of the overall process and a low or zero-carbon footprint. Thermal systems used for recovering H2 from ammonia require a reaction unit and catalyst that operates at a high temperature (550–800 ◦C) for the complete conversion of ammonia which has a negative effect on the economics of the process. A non-thermal plasma (NTP) solution is the answer to this problem. Ammonia becomes a reliable hydrogen carrier and in combination with NTP offers the high conversion of the dehydrogenation process at a relatively low temperature so that zero-carbon pure hydrogen can be transported over long distances. This paper provides a critical overview of ammonia decomposition systems that focus on non-thermal methods especially under plasma conditions. The review shows that the process has various positive aspects and is an innovative process that has only been reported to a limited extent.
Thermocatalytic Hydrogen Production Through Decomposition of Methane-A Review
Oct 2021
Publication
Consumption of fossil fuels especially in transport and energy-dependent sectors has led to large greenhouse gas production. Hydrogen is an exciting energy source that can serve our energy purposes and decrease toxic waste production. Decomposition of methane yields hydrogen devoid of COx components thereby aiding as an eco-friendly approach towards large-scale hydrogen production. This review article is focused on hydrogen production through thermocatalytic methane decomposition (TMD) for hydrogen production. The thermodynamics of this approach has been highlighted. Various methods of hydrogen production from fossil fuels and renewable resources were discussed. Methods including steam methane reforming partial oxidation of methane auto thermal reforming direct biomass gasification thermal water splitting methane pyrolysis aqueous reforming and coal gasification have been reported in this article. A detailed overview of the different types of catalysts available the reasons behind their deactivation and their possible regeneration methods were discussed. Finally we presented the challenges and future perspectives for hydrogen production via TMD. This review concluded that among all catalysts nickel ruthenium and platinum-based catalysts show the highest activity and catalytic efficiency and gave carbon-free hydrogen products during the TMD process. However their rapid deactivation at high temperatures still needs the attention of the scientific community.
Hydrogen Production by Solar Thermochemical Water-Splitting Cycle via a Beam Down Concentrator
May 2021
Publication
About 95% of the hydrogen presently produced is from natural gas and coal and the remaining 5% is generated as a by-product from the production of chlorine through electrolysis1 . In the hydrogen economy (Crabtree et al. 2004; Penner 2006; Marbán and Valdés-Solís 2007) hydrogen is produced entirely from renewable energy. The easiest approach to advance renewable energy production is through solar photovoltaic and electrolysis a pathway of high technology readiness level (TRL) suffering however from two downfalls. First of all electricity is already an energy carrier and transformation with a penalty into another energy carrier hydrogen is in principle flawed. The second problem is that the efficiency of commercial solar panels is relatively low. The cadmium telluride (CdTe) thin-film solar cells have a solar energy conversion efficiency of 17%. Production of hydrogen using the current best processes for water electrolysis has an efficiency of ∼70%. As here explained the concentrated solar energy may be used to produce hydrogen using thermochemical water-splitting cycles at much global higher efficiency (fuel energy to incident sun energy). This research and development (R&D) effort is therefore undertaken to increase the TRL of this approach as a viable and economical option.
A Green Route for Hydrogen Producton from Alkaline Thermal Treatment (ATT) of Biomass with Carbon Storage
Apr 2023
Publication
Hydrogen a green energy carrier is one of the most promising energy sources. However,it is currently mainly produced from depleting fossil fuels with high carbon emissions which has serious negative effects on the economy and environment. To address this issue sustainable hydrogen production from bio-energy with carbon capture and storage (HyBECCS) is an ideal technology to reduce global carbon emissions while meeting energy demand. This review presents an overview of the latest progress in alkaline thermal treatment (ATT) of biomass for hydrogen production with carbon storage especially focusing on the technical characteristics and related challenges from an industrial application perspective. Additionally the roles of alkali and catalyst in the ATT process are critically discussed and several aspects that have great influences on the ATT process such as biomass types reaction parameters and reactors are expounded. Finally the potential solutions to the general challenges and obstacles to the future industrial-scale application of ATT of biomass for hydrogen production are proposed.
Hydrogen Production by Water Electrolysis Technologies: A Review
Sep 2023
Publication
Hydrogen as an energy source has been identified as an optimal pathway for mitigating climate change by combining renewable electricity with water electrolysis systems. Proton exchange membrane (PEM) technology has received a substantial amount of attention because of its ability to efficiently produce high-purity hydrogen while minimising challenges associated with handling and maintenance. Another hydrogen generation technology alkaline water electrolysis (AWE) has been widely used in commercial hydrogen production applications. Anion exchange membrane (AEM) technology can produce hydrogen at relatively low costs because the noble metal catalysts used in PEM and AWE systems are replaced with conventional low-cost electrocatalysts. Solid oxide electrolyzer cell (SOEC) technology is another electrolysis technology for producing hydrogen at relatively high conversion efficiencies low cost and with low associated emissions. However the operating temperatures of SOECs are high which necessitates long startup times. This review addresses the current state of technologies capable of using impure water in water electrolysis systems. Commercially available water electrolysis systems were extensively discussed and compared. The technical barriers of hydrogen production by PEM and AEM were also investigated. Furthermore commercial PEM stack electrolyzer performance was evaluated using artificial river water (soft water). An integrated system approach was recommended for meeting the power and pure water demands using reversible seawater by combining renewable electricity water electrolysis and fuel cells. AEM performance was considered to be low requiring further developments to enhance the membrane’s lifetime.
Comparative Exergy and Environmental Assessment of the Residual Biomass Gasification Routes for Hydrogen and Ammonia Production
Jul 2023
Publication
The need to reduce the dependency of chemicals on fossil fuels has recently motivated the adoption of renewable energies in those sectors. In addition due to a growing population the treatment and disposition of residual biomass from agricultural processes such as sugar cane and orange bagasse or even from human waste such as sewage sludge will be a challenge for the next generation. These residual biomasses can be an attractive alternative for the production of environmentally friendly fuels and make the economy more circular and efficient. However these raw materials have been hitherto widely used as fuel for boilers or disposed of in sanitary landfills losing their capacity to generate other by-products in addition to contributing to the emissions of gases that promote global warming. For this reason this work analyzes and optimizes the biomass-based routes of biochemical production (namely hydrogen and ammonia) using the gasification of residual biomasses. Moreover the capture of biogenic CO2 aims to reduce the environmental burden leading to negative emissions in the overall energy system. In this context the chemical plants were designed modeled and simulated using Aspen plus™ software. The energy integration and optimization were performed using the OSMOSE Lua Platform. The exergy destruction exergy efficiency and general balance of the CO2 emissions were evaluated. As a result the irreversibility generated by the gasification unit has a relevant influence on the exergy efficiency of the entire plant. On the other hand an overall negative emission balance of −5.95 kgCO2/kgH2 in the hydrogen production route and −1.615 kgCO2/kgNH3 in the ammonia production route can be achieved thus removing from the atmosphere 0.901 tCO2/tbiomass and 1.096 tCO2/tbiomass respectively.
Blue Hydrogen Production from Natural Gas Reservoirs: A Review of Application and Feasibility
Feb 2023
Publication
Recently interest in developing H2 strategies with carbon capture and storage (CCS) technologies has surged. Considering that this paper reviews recent literature on blue H2 a potential low-carbon short-term solution during the H2 transition period. Three key aspects were the focus of this paper. First it presents the processes used for blue H2 production. Second it presents a detailed comparison between blue H2 and natural gas as fuels and energy carriers. The third aspect focuses on CO2 sequestration in depleted natural gas reservoirs an essential step for implementing blue H2. Globally ~ 75% of H2 is produced using steam methane reforming which requires CCS to obtain blue H2. Currently blue H2 needs to compete with other advancing technologies such as green H2 solar power battery storage etc. Compared to natural gas and liquefied natural gas blue H2 gas results in lower CO2 emissions since CCS is applied. However transporting liquefied and compressed blue H2 entails higher energy economic and environmental costs. CCS must be appropriately implemented to produce blue H2 successfully. Due to their established capacity to trap hydrocarbons over geologic time scales depleted natural gas reservoirs are regarded as a viable option for CCS. Such a conclusion is supported by several simulation studies and field projects in many countries. Additionally there is much field experience and knowledge on the injection and production performance of natural gas reservoirs. Therefore using the existing site infrastructure converting these formations into storage reservoirs is undemanding.
Energy Performance Assessment of a Solar-driven Thermochemical Cycle Device for Green Hydrogen Production
Sep 2023
Publication
This paper presents a novel dynamic simulation model for assessing the energy performance of solar-driven systems employed in green hydrogen production. The system consists of a parabolic dish collector that focuses solar radiation on two cerium-based thermochemical reactors. The model is based on a transient finitedifference method to simulate the thermal behaviour of the system and it integrates a theoretical analysis of materials and operating principles. Different empirical data were considered for experimentally validating it: a good agreement between experimental and simulated results was obtained for the temperatures calculated inside the thermochemical reactor (R2 = 0.99 MAPE = 6.3%) and the hourly flow rates of hydrogen oxygen and carbon monoxide (R2 = 0.96 MAPE = 10%) inside the thermochemical reactor. The model was implemented in a MatLab tool for the system dynamic analysis under different boundary conditions. Subsequently to explore the capability of this approach the developed tool was used for analysing the examined device operating in twelve different weather zones. The obtained results comprise heat maps of specific crucial instants and hourly dynamic trends showing redox reaction cycles occurring into the thermochemical reactors. The yearly hydrogen production ranges from 1.19 m3 /y to 1.64 m3 /y according to the hourly incident solar radiations outdoor air temperatures and wind speeds. New graphic tools for rapid feasibility studies are presented. The developed tools and the obtained results can be useful to the basic design of this technology and for the multi-objective optimization of its layout and main design/operating parameters.
Contribution to Net Zero Emissions of Integrating Hydrogen Production in Wastewater Treatment Plants
Jul 2023
Publication
The reliability of renewable hydrogen supply for off-take applications is critical to the future sustainable energy economy. Integrated water electrolysis can be deployed at distributed municipal wastewater treatment plants (WWTP) creating opportunity for reduction in carbon emissions through direct and indirect use of the electrolysis output. A novel energy shifting process where the co-produced oxygen is compressed and stored to enhance the utilisation of intermittent renewable electricity is analysed. The hydrogen produced can be used in local fuel cell electric buses to replace incumbent diesel buses for public transport. However quantifying the extent of carbon emission reduction of this conceptual integrated system is key. In this study the integration of hydrogen production at a case study WWTP of 26000 EP capacity and using the hydrogen in buses was compared with two conventional systems: the base case of a WWTP with grid electricity consumption offset by solar PV and the community’s independent use of diesel buses for transport and the non-integrated configuration with hydrogen produced at the bus refuelling location operated independently of the WWTP. The system response was analysed using a Microsoft Excel simulation model with hourly time steps over a 12-month time frame. The model included a control scheme for the reliable supply of hydrogen for public transport and oxygen to the WWTP and considered expected reductions in carbon intensity of the national grid level of solar PV curtailment electrolyser efficiency and size of the solar PV system. Results showed that by 2031 when Australia’s national electricity is forecast to achieve a carbon intensity of less than 0.186 kg CO2-e/kWh integrating water electrolysis at a municipal WWTP for producing hydrogen for use in local hydrogen buses produced less carbon emissions than continuing to use diesel buses and offsetting emissions by exporting renewable electricity to the grid. By 2034 an annual reduction of 390 t–CO2–e is expected after changing to the integrated configuration. Considering electrolyser efficiency improvements and curtailment of renewable electricity the reduction increases to 872.8 t–CO2–e.
Evaluation of Surplus Hydroelectricity Potential in Nepal until 2040 and its Use for Hydrogen Production Via Electrolysis
May 2023
Publication
The abundant hydro resources in Nepal have resulted in the generation of electricity almost exclusively from hydropower plants. Several hydropower plants are also currently under construction. There is no doubt that the surplus electricity will be significantly high in the coming years. Given the previous trend in electricity consumption it will be a challenge to maximize the use of surplus electricity. In this work the potential solutions to maximize the use of this surplus electricity have been analysed. Three approached are proposed: (i) increasing domestic electricity consumption by shifting the other energy use sectors to electricity (ii) cross-border export of electricity and (iii) conversion of electricity to hydrogen via electrolysis. The current state of energy demand and supply patterns in the country are presented. Future monthly demand forecasts and surplus electricity projections have been made. The hydrogen that can be produced with the surplus electricity via electrolysis is determined and an economic assessment is carried out for the produced hydrogen. The analysis of levelized cost of hydrogen (LCOH) under different scenarios resulted values ranging from 3.8 €/kg to 4.5 €/kg.
Is the Polish Solar-to-Hydrogen Pathway Green? A Carbon Footprint of AEM Electrolysis Hydrogen Based on an LCA
Apr 2023
Publication
Efforts to direct the economies of many countries towards low-carbon economies are being made in order to reduce their impact on global climate change. Within this process replacing fossil fuels with hydrogen will play an important role in the sectors where electrification is difficult or technically and economically ineffective. Hydrogen may also play a critical role in renewable energy storage processes. Thus the global hydrogen demand is expected to rise more than five times by 2050 while in the European Union a seven-fold rise in this field is expected. Apart from many technical and legislative barriers the environmental impact of hydrogen production is a key issue especially in the case of new and developing technologies. Focusing on the various pathways of hydrogen production the essential problem is to evaluate the related emissions through GHG accounting considering the life cycle of a plant in order to compare the technologies effectively. Anion exchange membrane (AEM) electrolysis is one of the newest technologies in this field with no LCA studies covering its full operation. Thus this study is focused on a calculation of the carbon footprint and economic indicators of a green hydrogen plant on the basis of a life cycle assessment including the concept of a solar-to-hydrogen plant with AEM electrolyzers operating under Polish climate conditions. The authors set the range of the GWP indicators as 2.73–4.34 kgCO2eq for a plant using AEM electrolysis which confirmed the relatively low emissivity of hydrogen from solar energy also in relation to this innovative technology. The economic profitability of the investment depends on external subsidies because as developing technology the AEM electrolysis of green hydrogen from photovoltaics is still uncompetitive in terms of its cost without this type of support.
Decommissioning Platforms to Offshore Solar System: Road to Green Hydrogen Production from Seawater
May 2023
Publication
With more than 140 offshore platforms identified in Malaysian water to be decommissioned within 10 years it is critical for the Oil and Gas operators to re-evaluate the overall decommissioning strategies for a more sustainable approach. A revision to the current decommissioning options with inclusion of green decommissioning plan to the overall decision tree will assist in accelerating sustainable decision making. Using the advantage of the available 3D modelling from Naviswork and convert to PVSyst software for solar analysis to the one of the shortlisted offshore gas complexes in Malaysia three solar powered generation scenario was evaluated with aimed to establish the best integrated system on a modified decommissioned unmanned processing platform to generate cleaner energy. Financial assessment inclusive of Levelized Cost of Electricity as well as environmental assessment for each scenario are evaluated together. From the study optimum tilt angle was determined resulted to best annual solar yield of 257MWh with performance ratio (PR) of 87% for on-grid scenario 1. Off-grid scenario 3 is used to understand the estimated green hydrogen production. A desktop investigation conducted to three (3) type of electrolysers resulted to 8.6 kg to 18 kg of green hydrogen based on the average daily solar yield produced in scenario 3. Using Proton Electron Membrane electrolyser to simulate the PV solar-to-hydrogen offshore system it is observed that 98% of annual solar fraction can be achieved with annual performance ratio of 74.5% with levelized cost of Hydrogen (LCOH) of $10.95 per kg. From financial assessment this study justifies platforms repurpose to renewable energy concept to be an attractive option since cost to decommission the identified complex was observed to be 11 times greater compared to investing for this proposed concept.
System-friendly Process Design: Optimizing Blue Hydrogen Production for Future Energy Systems
Aug 2022
Publication
While the effects of ongoing cost reductions in renewables batteries and electrolyzers on future energy systems have been extensively investigated the effects of significant advances in CO2 capture and storage (CCS) technologies have received much less attention. This research gap is addressed via a long-term (2050) energy system model loosely based on Germany yielding four main findings. First CCS-enabled pathways offer the greatest benefits in the hydrogen sector where hydrogen prices can be reduced by two-thirds relative to a scenario without CCS. Second advanced blue hydrogen technologies can reduce total system costs by 12% and enable negative CO2 emissions due to higher efficiencies and CO2 capture ratios. Third co-gasification of coal and biomass emerged as an important enabler of these promising results allowing efficient exploitation of limited biomass resources to achieve negative emissions and limit the dependence on imported natural gas. Finally CCS decarbonization pathways can practically and economically incorporate substantial shares of renewable energy to reduce fossil fuel dependence. Such diversification of primary energy inputs increases system resilience to the broad range of socio-techno-economic challenges facing the energy transition. In conclusion balanced blue-green pathways offer many benefits and deserve serious consideration in the global decarbonization effort.
Simulation and Techno-Economic Assessment of Hydrogen Production from Biomass Gasification-Based Processes: A Review
Nov 2022
Publication
The development of low-carbon fuels from renewable resources is a key measure to reduce carbon dioxide emissions and mitigate climate change. Biomass gasification with subsequent gas processing and purification is a promising route to produce low-carbon hydrogen. In the past decade simulation-based modelling using Aspen Plus software has supported the investigation of future potential industrial applications of this pathway. This article aims to provide a review of the modelling and economic assessment of woody biomass gasification-based hydrogen production with focus on the evaluation of the model accuracy in predicting producer gas composition in comparison with experimental data depending on the approach implemented. The assessment of comprehensive models which integrate biomass gasification with gas processing and purification highlights how downstream gas processing could improve the quality of the syngas and thus the hydrogen yield. The information in this article provides an overview of the current practices challenges and opportunities for future research particularly for the development of a comprehensive pathway for hydrogen production based on biomass gasification. Moreover this review includes a techno-economic assessment of biomass to hydrogen processes which will be useful for implementation at industrial-scale.
Techno-economic Analysis to Identify the Optimal Conditions for Green Hydrogen Production
Jun 2023
Publication
The intermittency of renewable energy sources necessitates energy storage to meet the full demand and balancing requirements of the grid. Green hydrogen (H2) is a chemical energy carrier that can be used in a flexible manner and store large amounts of energy for long periods of time. This techno-economic analysis investigates H2 production from wind using commercially available desalination and electrolysis units. Proton exchange membrane and alkaline electrolyser units are utilised and compared. The intermittency of wind is examined with comparison against grid-bought electricity. A model is developed to determine the selling price required to ensure profitability over a 10-year period. Firstly where H2 is produced using energy from the grid with electricity purchased when below a specified price point or between specified hours. In the second scenario a wind turbine is owned by the user and the electricity price is not considered while the turbine capital expenditure is. The price of H2 production from wind is found to be comparable with natural gas derived H2 at a larger scale with a minimum selling price calculated to be 4.85 £/kg at a setpoint of 500 kg of H2/hr. At a setpoint of 50 kg of H2/hr this is significantly higher at 12.10 £/kg. In both cases the alkaline electrolyser produced cheaper H2. This study demonstrates an economy of scale with H2 prices decreasing with increased scale. H2 prices are also closely linked to the capital expenditure with the equipment size space and safety identified as limiting factors.
Optimal Renewable Energy Distribution Between Gasifier and Electrolyzer for Syngas Generation in a Power and Biomass-to-Liquid Fuel Process
Jan 2022
Publication
By adding energy as hydrogen to the biomass-to-liquid (BtL) process several published studies have shown that carbon efficiency can be increased substantially. Hydrogen can be produced from renewable electrical energy through the electrolysis of water or steam. Adding high-temperature thermal energy to the gasifier will also increase the overall carbon efficiency. Here an economic criterion is applied to find the optimal distribution of adding electrical energy directly to the gasifier as opposed to the electrolysis unit. Three different technologies for electrolysis are applied: solid oxide steam electrolysis (SOEC) alkaline water electrolysis (AEL) and proton exchange membrane (PEM). It is shown that the addition of part of the renewable energy to the gasifier using electric heaters is always beneficial and that the electrolysis unit operating costs are a significant portion of the costs. With renewable electricity supplied at a cost of 50 USD/MWh and a capital cost of 1500 USD/kW installed SOEC the operating costs of electric heaters and SOEC account for more than 70% of the total costs. The energy efficiency of the electrolyzer is found to be more important than the capital cost. The optimal amount of energy added to the gasifier is about 37–39% of the energy in the biomass feed. A BtL process using renewable hydrogen imports at 2.5 USD/kg H2 or SOEC for hydrogen production at reduced electricity prices gives the best values for the economic objective.
Grid-supported Electrolytic Hydrogen Production: Cost of Climate Impact Using Dynamic Emission Factors
Aug 2023
Publication
Hydrogen production based on a combination of intermittent renewables and grid electricity is a promising approach for reducing emissions in hard-to-decarbonise sectors at lower costs. However for such a configuration to provide climate benefits it is crucial to ensure that the grid electricity consumed in the process is derived from low-carbon sources. This paper examined the use of hourly grid emission factors (EFs) to more accurately determine the short-term climate impact of dynamically operated electrolysers. A model of the interconnected northern European electricity system was developed and used to calculate average grid-mix and marginal EFs for the four bidding zones in Sweden. Operating a 10 MW electrolyser using a combination of onshore wind and grid electricity was found to decrease the levelised cost of hydrogen (LCOH) to 2.40–3.63 €/kgH2 compared with 4.68 €/kgH2 for wind-only operation. A trade-off between LCOH and short-term climate impact was revealed as specific marginal emissions could exceed 20 kgCO2eq/kgH2 at minimum LCOH. Both an emission-minimising operating strategy and an increased wind-to-electrolyser ratio was found to manage this trade-off by enabling simultaneous cost and emission reductions lowering the marginal carbon abatement cost (CAC) from 276.8 €/tCO2eq for wind-only operation to a minimum of 222.7 and 119.3 €/tCO2eq respectively. Both EF and LCOH variations were also identified between the bidding zones but with no notable impact on the marginal CAC. When using average grid-mix emission factors the climate impact was low and the CAC could be reduced to 71.3–200.0 €/tCO2eq. In relation to proposed EU policy it was demonstrated that abiding by hourly renewable temporal matching principles could ensure low marginal emissions at current levels of fossil fuels in the electricity mix.
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