Germany
H2-powered Aviation - Design and Economics of Green LH2 Supply for Airports
Aug 2023
Publication
The economic competitiveness of hydrogen-powered aviation highly depends on the supply costs of green liquid hydrogen to enable true-zero CO2 flying. This study uses non-linear energy system optimization to analyze three main liquid hydrogen (LH2) supply pathways for five locations. Final liquid hydrogen costs at the dispenser supply costs could reach 2.04 USD/kgLH2 in a 2050 base case scenario for locations with strong renewable energy source conditions. This could lead to cost-competitive flying with hydrogen. Reflecting techno-economic uncertainties in two additional scenarios the liquid hydrogen cost span at all five airport locations ranges between 1.37–3.48 USD/kgLH2 if hydrogen import options from larger hydrogen markets are also available. Import setups are of special importance for airports with a weaker renewable energy source situation e.g. selected Central European airports. There on-site supply might not only be too expensive but space requirements for renewable energy sources could be too large for feasible implementation in densely populated regions. Furthermore main costs for liquid hydrogen are caused by renewable energy sources electrolysis systems and liquefaction plants. Seven detailed design rules are derived for optimized energy systems for these and the storage components. This and the cost results should help infrastructure planners and general industry and policy players prioritize research and development needs
Hydrogen from Waste Gasification
Feb 2024
Publication
Hydrogen is a versatile energy vector for a plethora of applications; nevertheless its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper recent developments in R&D on waste gasification (municipal solid waste tires plastic waste) are summarised and an overview about suitable gasification processes is given. A literature survey indicated that a broad span of hydrogen relates to productivity depending on the feedstock ranging from 15 to 300 g H2/kg of feedstock. Suitable gas treatment (upgrading and separation) is also covered presenting both direct and indirect (chemical looping) concepts. Hydrogen production via gasification offers a high productivity potential. However regulations like frame conditions or subsidies are necessary to bring the technology into the market.
Hydrogen Liquefaction: A Review of the Fundamental Physics, Engineering Practice and Future Opportunities
Apr 2022
Publication
Hydrogen is emerging as one of the most promising energy carriers for a decarbonised global energy system. Transportation and storage of hydrogen are critical to its large-scale adoption and to these ends liquid hydrogen is being widely considered. The liquefaction and storage processes must however be both safe and efficient for liquid hydrogen to be viable as an energy carrier. Identifying the most promising liquefaction processes and associated transport and storage technologies is therefore crucial; these need to be considered in terms of a range of interconnected parameters ranging from energy consumption and appropriate materials usage to considerations of unique liquid-hydrogen physics (in the form of ortho–para hydrogen conversion) and boil-off gas handling. This study presents the current state of liquid hydrogen technology across the entire value chain whilst detailing both the relevant underpinning science (e.g. the quantum behaviour of hydrogen at cryogenic temperatures) and current liquefaction process routes including relevant unit operation design and efficiency. Cognisant of the challenges associated with a projected hydrogen liquefaction plant capacity scale-up from the current 32 tonnes per day to greater than 100 tonnes per day to meet projected hydrogen demand this study also reflects on the next-generation of liquid-hydrogen technologies and the scientific research and development priorities needed to enable them.
Towards Green Hydrogen? - A Comparison of German and African Visions and Expectations in the Context of the H2Atlas-Africa Project
Sep 2023
Publication
Green hydrogen promises to be critical in achieving a sustainable and renewable energy transition. As green hydrogen is produced with renewables green hydrogen could become an energy storage medium of the future and even substitute the current unsustainable grey or blue hydrogen used in the industry. Bringing this transition into reality for instance in Germany there are visions to rapidly build hydrogen facilities in Africa and export the produced green hydrogen to Europe. One problem however is that these visions presumably conflict with the visions of actors within Africa. Therefore this study aims to provide an initial assessment of African stakeholders’ visions for future energy exports and renewable energy expectations. By comparing visions from Germany and Africa this assessment was conducted to identify differences in green energy and hydrogen visions that could lead to conflict and similarities that could be the basis for cooperation. The National Hydrogen Strategy outlines the German visions which clarifies that Germany will have to import green hydrogen to meet its green transition target. In this context of future energy export demand a partnership between German and African researchers on assessing green hydrogen potentials in Africa started. The African visions were explored by surveying the partners from different African countries working on the project. The results revealed that while both sides see the need for an immediate transition to renewable energy the African side is not envisioning the immediate export of green hydrogen. Based on the responses the partners are primarily concerned with improving the continent’s still deficient energy access for both the population and industry. Nevertheless this African perspective greatly emphasises cross-border cooperation where both sides can realise their visions. In the case of Germany that German investment could build infrastructure which would benefit the receiving African country or countries and open up the possibility for the envisioned green hydrogen export to Europe.
Preventing Hydrogen Embrittlement: The Role of Barrier Coatings for the Hydrogen Economy
May 2023
Publication
Hydrogen barrier coatings are protective layers consisting of materials with a low intrinsic hydrogen diffusivity and solubility showing the potential to delay reduce or hinder hydrogen permeation. Hydrogen barrier coatings are expected to enable steels which are susceptible to hydrogen embrittlement specifically cost-effective low alloy-steels or light-weight high-strength steels for applications in a hydrogen economy. Predominantly ceramic coating materials have been investigated for this purpose including oxides nitrides and carbides. In this review the state of the art with respect to hydrogen permeation is discussed for a variety of coatings. Al2O3 TiAlN and TiC appear to be the most promising candidates from a large pool of ceramic materials. Coating methods are compared with respect to their ability to produce layers with suitable quality and their potential for scaling up for industrial use. Different setups for the characterisation of hydrogen permeability are discussed using both gaseous hydrogen and hydrogen originating from an electrochemical reaction. Finally possible pathways for improvement and optimisation of hydrogen barrier coatings are outlined.
On the Road to Sustainable Transport: Acceptance and Preferences for Renewable Fuel Production Infrastructure
Sep 2022
Publication
To abate climate change and ameliorate the air quality in urban areas innovative solutions are required to reduce CO2 and pollutant emissions from traffic. Alternative fuels made from biomass or CO2 and hydrogen can contribute to these goals by substituting fossil gasoline or diesel in combustion engines. Using a conjoint analysis approach the current study investigates preferences of laypeople (n = 303) for fuel production facilities in terms of siting location plant size raw material used in the production and raw material transport. The location was most decision-relevant followed by raw material transport whereas plant size and type of raw material played a less prominent role for the preference choice. The best-case scenario from the point of view of acceptance would be the installation of a rather small bio-hybrid fuel production plant in an industrial area (instead of an agricultural or pristine environment). No transport or transport via underground pipeline were preferred over truck/tank car or overground pipeline. The findings can be used as a basis for planning and decision-making for designing production networks for new fuel types.
Subsurface Renewable Energy Storage Capcity for Hydrogen, Methane and Compress Air - A Performance Assessment Study from the North German Basin
Jul 2021
Publication
The transition to renewable energy sources to mitigate climate change will require large-scale energy storage to dampen the fluctuating availability of renewable sources and to ensure a stable energy supply. Energy storage in the geological subsurface can provide capacity and support the cycle times required. This study investigates hydrogen storage methane storage and compressed air energy storage in subsurface porous formations and quantifies potential storage capacities as well as storage rates on a site-specific basis. For part of the North German Basin used as the study area potential storage sites are identified employing a newly developed structural geological model. Energy storage capacities estimated from a volume-based approach are 6510 TWh and 24544 TWh for hydrogen and methane respectively. For a consistent comparison of storage capacities including compressed air energy storage the stored exergy is calculated as 6735 TWh 25795 TWh and 358 TWh for hydrogen methane and compressed air energy storage respectively. Evaluation of storage deliverability indicates that high deliverability rates are found mainly in two of the three storage formations considered. Even accounting for the uncertainty in geological parameters the storage potential for the three considered storage technologies is significantly larger than the predicted demand and suitable storage rates are achievable in all storage formations.
Synthetic Fuels in the German Industry Sector Depending on Climate Protection Level
Aug 2021
Publication
Especially the electrification of the industry sector is highly complex and challenging mainly due to process-specific requirements. In this context there are several industrial processes where the direct and indirect use of electricity is subject to technical restrictions. In order to achieve the national climate goals the fossil energy consumption remaining after the implementation of efficiency and sufficiency measures as well as direct electrification has to be substituted through hydrogen and synthetic gaseous liquid and solid hydrocarbons. As the main research object the role of synthetic fuels in industrial transformation paths is investigated and analyzed by combining individual greenhouse gas abatement measures within the Sector Model Industry. Sector Model Industry is an energy consumption model that performs discrete deterministic energy and emission dynamic calculations with a time horizon up to 2050 at macroeconomic level. The results indicate that the use of synthetic fuels can be expected with a high level of climate protection. The industrial CO2 target in the model makes it necessary to replace CO2 -intensive fossil with renewable fuels. The model uses a total of 163 TWh of synthetic fuels in the climate protection scenario and thus achieves an 88% decrease in CO2 emissions in 2050 compared to 1990. This means that the GHG abatement achieved in industry is within the range of the targeted CO2 mitigation of the overall system in Germany of between 80 and 95% in 2050 compared to 1990. Due to technical restrictions the model mainly uses synthetic methane instead of hydrogen (134 TWh). The results show that despite high costs synthetic fuels are crucial for defossilization as a fall back option in the industrial scenario considering high climate ambition. The scenario does not include hydrogen technologies for heat supply. Accordingly the climate protection scenario uses hydrogen only in the steel industry for the direct reduction of iron (21 TWh). 8 TWh of synthetic oil substitute the same amount of fossil oil in the climate protection scenario. A further analysis conducted on the basis of the model results shows that transformation in the energy system and the use of smart ideas concepts and technologies are a basic prerequisite for enabling the holistic defossilisation of industry. The findings in the research can contribute to the cost-efficient use of synthetic fuels in industry and thus serve as a basis for political decision making. Moreover the results may have a practical relevance not only serving as a solid comparison base for the outcome of other studies but also as input data for further simulation of energy system transformation paths.
Economically Viable Large-scale Hydrogen Liquefaction
Mar 2016
Publication
The liquid hydrogen demand particularly driven by clean energy applications will rise in the near future. As industrial large scale liquefiers will play a major role within the hydrogen supply chain production capacity will have to increase by a multiple of today’s typical sizes. The main goal is to reduce the total cost of ownership for these plants by increasing energy efficiency with innovative and simple process designs optimized in capital expenditure. New concepts must ensure a manageable plant complexity and flexible operability. In the phase of process development and selection a dimensioning of key equipment for large scale liquefiers such as turbines and compressors as well as heat exchangers must be performed iteratively to ensure technological feasibility and maturity. Further critical aspects related to hydrogen liquefaction e.g. fluid properties ortho-para hydrogen conversion and coldbox configuration must be analysed in detail. This paper provides an overview on the approach challenges and preliminary results in the development of efficient as well as economically viable concepts for large-scale hydrogen liquefaction.
Greenhouse Gas Emissions Performance of Electric, Hydrogen and Fossil-Fuelled Freight Trucks with Uncertainty Estimates Using a Probabilistic Life-Cycle Assessment (pLCA)
Jan 2024
Publication
This research conducted a probabilistic life-cycle assessment (pLCA) into the greenhouse gas (GHG) emissions performance of nine combinations of truck size and powertrain technology for a recent past and a future (largely decarbonised) situation in Australia. This study finds that the relative and absolute life-cycle GHG emissions performance strongly depends on the vehicle class powertrain and year of assessment. Life-cycle emission factor distributions vary substantially in their magnitude range and shape. Diesel trucks had lower life-cycle GHG emissions in 2019 than electric trucks (battery hydrogen fuel cell) mainly due to the high carbon-emission intensity of the Australian electricity grid (mainly coal) and hydrogen production (mainly through steam–methane reforming). The picture is however very different for a more decarbonised situation where battery electric trucks in particular provide deep reductions (about 75–85%) in life-cycle GHG emissions. Fuel-cell electric (hydrogen) trucks also provide substantial reductions (about 50–70%) but not as deep as those for battery electric trucks. Moreover hydrogen trucks exhibit the largest uncertainty in emissions performance which reflects the uncertainty and general lack of information for this technology. They therefore carry an elevated risk of not achieving the expected emission reductions. Battery electric trucks show the smallest (absolute) uncertainty which suggests that these trucks are expected to deliver the deepest and most robust emission reductions. Operational emissions (on-road driving and vehicle maintenance combined) dominate life-cycle emissions for all vehicle classes. Vehicle manufacturing and upstream emissions make a relatively small contribution to life-cycle emissions from diesel trucks (
Deep Learning for Wind and Solar Energy Forecasting in Hydrogen Production
Feb 2024
Publication
This research delineates a pivotal advancement in the domain of sustainable energy systems with a focused emphasis on the integration of renewable energy sources—predominantly wind and solar power—into the hydrogen production paradigm. At the core of this scientific endeavor is the formulation and implementation of a deep-learning-based framework for short-term localized weather forecasting specifically designed to enhance the efficiency of hydrogen production derived from renewable energy sources. The study presents a comprehensive evaluation of the efficacy of fully connected neural networks (FCNs) and convolutional neural networks (CNNs) within the realm of deep learning aimed at refining the accuracy of renewable energy forecasts. These methodologies have demonstrated remarkable proficiency in navigating the inherent complexities and variabilities associated with renewable energy systems thereby significantly improving the reliability and precision of predictions pertaining to energy output. The cornerstone of this investigation is the deployment of an artificial intelligence (AI)-driven weather forecasting system which meticulously analyzes data procured from 25 distinct weather monitoring stations across Latvia. This system is specifically tailored to deliver short-term (1 h ahead) forecasts employing a comprehensive sensor fusion approach to accurately predicting wind and solar power outputs. A major finding of this research is the achievement of a mean squared error (MSE) of 1.36 in the forecasting model underscoring the potential of this approach in optimizing renewable energy utilization for hydrogen production. Furthermore the paper elucidates the construction of the forecasting model revealing that the integration of sensor fusion significantly enhances the model’s predictive capabilities by leveraging data from multiple sources to generate a more accurate and robust forecast. The entire codebase developed during this research endeavor has been made available on an open access GIT server.
Benchmark Study for the Simulation of Underground Hydrogen Storage Operations
Aug 2022
Publication
While the share of renewable energy sources increased within the last years with an ongoing upward trend the energy sector is facing the problem of storing large amounts of electrical energy properly. To compensate daily and seasonal fluctuations a sufficient storage system has to be developed. The storage of hydrogen in the subsurface referred to as Underground Hydrogen Storage (UHS) shows potential to be a solution for this problem. Hydrogen produced from excess energy via electrolysis is injected into a subsurface reservoir and withdrawn when required. As hydrogen possesses unique thermodynamic properties many commonly used correlations can not be simply transferred to a system with a high hydrogen content. Mixing processes with the present fluids are essential to be understood to achieve high storage efficiencies. Additionally in the past microbial activity e.g. by methanogenic archaea was observed leading to a changing fluid composition over time. To evaluate the capability of reservoir simulators to cover these processes the present study establishes a benchmark scenario of an exemplary underground hydrogen storage scenario. The benchmark comprises of a generic sandstone gas reservoir and a typical gas storage schedule is defined. Based on this benchmark the present study assesses the capabilities of the commercial simulator Schlumberger ECLIPSE and the open-source simulator DuMux to mimic UHS related processes such as hydrodynamics but also microbial activity. While ECLIPSE offers a reasonable mix of user-friendliness and computation time DuMux allows for a better adjustment of correlations and the implementation of biochemical reactions. The corresponding input data (ECLIPSE format) and relevant results are provided in a repository to allow this simulation study’s reproduction and extension.
Stakeholder Perspectives on the Scale-up of Green Hydrogen and Electrolyzers
Nov 2023
Publication
Green hydrogen is a promising alternative to fossil fuels. However current production capacities for electrolyzers and green hydrogen are not in line with national political goals and projected demand. Considering these issues we conducted semi-structured interviews to determine the narratives of different stakeholders during this transformation as well as challenges and opportunities for the green hydrogen value chain. We interviewed eight experts with different roles along the green hydrogen value chain ranging from producers and consumers of green hydrogen to electrolyzer manufacturers and consultants as well as experts from the political sphere. Most experts see the government as necessary for scale-up by setting national capacity targets policy support and providing subsidies. However the experts also accuse the governments of delaying development through overregulation and long implementation times for regulations. The main challenges that were identified are the current lack of renewable electricity and demand for green hydrogen. Demand for green hydrogen is influenced by supply costs which partly depend on prices for electrolyzers. However one key takeaway of the interviews is the skeptical assessments by the experts on the currently discussed estimates for price reduction potential of electrolyzers. While demand supply and prices are all factors that influence each other they result in feedback loops in investment decisions for the energy and manufacturing industries. A second key takeaway is that according to the experts current investment decisions in new production capacities are not solely dependent on short-term financial gains but also based on expected first mover advantages. These include experience and market share which are seen as factors for opportunities for future financial gains. Summarized the results present several challenges and opportunities for green hydrogen and electrolyzers and how to address them effectively. These insights contribute to a deeper understanding of the dynamics of the emerging green hydrogen value chain.
The Effects of Hydrogen Research and Innovation on International Hydrogen Trade
Feb 2024
Publication
Climate change and the pressure to decarbonize as well as energy security concerns have drawn the attention of policymakers and the industry to hydrogen energy. To advance the hydrogen economy at a global scale research and innovation progress is of significant importance among others. However previous studies have provided only limited quantitative evidence of the effects of research and innovation on the formation of a global hydrogen market. Instead they postulate rather than empirically support this relationship. Therefore this study analyzes the effects of research and innovation measured by scientific publications patents and standards on bilateral hydrogen trade flows for 32 countries between 1995 and 2019 in a gravity model of trade using regression analyses and Poisson Pseudo Maximum Likelihood (PPML) estimation. The main results of the PPML estimation show that research and innovation progress is indeed associated with increased trade especially with patenting and (international) standardization enhancing hydrogen export volumes. As policy implications we derive that increased public R&D funding can help increase the competitiveness of hydrogen energy and boost market growth along with infrastructure support and harmonized standards and regulations.
Performance Assessment of a 25 kW Solid Oxide Cell Module for Hydrogen Production and Power Generation
Jan 2024
Publication
Hydrogen produced via water electrolysis from renewable electricity is considered a key energy carrier to defossilize hard-to-electrify sectors. Solid oxide cells (SOC) based reactors can supply hydrogen not only in electrolysis but also in fuel cell mode when operating with (synthetic) natural gas or biogas at low conversion (polygeneration mode). However the scale-up of SOC reactors to the multi-MW scale is still a research topic. Strategies for transient operation depending on electricity intermittency still need to be developed. In this work a unique testing environment for SOC reactors allows reversible operation demonstrating the successful switching between electrolysis (− 75 kW) and polygeneration (25 kW) modes. Transient and steady state experiments show promising performance with a net hydrogen production of 53 kg day− 1 in SOEL operation with ca. − 75 kW power input. The experimental results validate the scaling approach since the reactor shows homogenous temperature profiles.
Assessing the Implications of Hydrogen Blending on the European Energy System towards 2050
Dec 2023
Publication
With the aim of reducing carbon emissions and seeking independence from Russian gas in the wake of the conflict in Ukraine the use of hydrogen in the European Union is expected to rise in the future. In this regard hydrogen transport via pipeline will become increasingly crucial either through the utilization of existing natural gas infrastructure or the construction of new dedicated hydrogen pipelines. This study investigates the effects of hydrogen blending in existing pipelines on the European energy system by the year 2050 by introducing hydrogen blending sensitivities to the Global Energy System Model (GENeSYS-MOD). Results indicate that hydrogen demand in Europe is inelastic and limited by its high costs and specific use cases with hydrogen production increasing by 0.17% for 100%-blending allowed compared to no blending allowed. The availability of hydrogen blending has been found to impact regional hydrogen production and trade with countries that can utilize existing natural gas pipelines such as Norway experiencing an increase in hydrogen and synthetic gas exports from 44.0 TWh up to 105.9 TWh in 2050 as the proportion of blending increases. Although the influence of blending on the overall production and consumption of hydrogen in Europe is minimal the impacts on the location of production and dependence on imports must be thoroughly evaluated in future planning efforts.
Analysis of the Levelized Cost of Renewable Hydrogen in Austria
Mar 2023
Publication
Austria is committed to the net-zero climate goal along with the European Union. This requires all sectors to be decarbonized. Hereby hydrogen plays a vital role as stated in the national hydrogen strategy. A report commissioned by the Austrian government predicts a minimum hydrogen demand of 16 TWh per year in Austria in 2040. Besides hydrogen imports domestic production can ensure supply. Hence this study analyses the levelized cost of hydrogen for an off-grid production plant including a proton exchange membrane electrolyzer wind power and solar photovoltaics in Austria. In the first step the capacity factors of the renewable electricity sources are determined by conducting a geographic information system analysis. Secondly the levelized cost of electricity for wind power and solarphotovoltaics plants in Austria is calculated. Thirdly the most cost-efficient portfolio of wind power and solar photovoltaics plants is determined using electricity generation profiles with a 10-min granularity. The modelled system variants differ among location capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. Finally selected variables are tested for their sensitivities. With the applied model the hydrogen production cost for decentralized production plants can be calculated for any specific location. The levelized cost of hydrogen estimates range from 3.08 EUR/kg to 13.12 EUR/kg of hydrogen whereas it was found that the costs are most sensitive to the capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. The novelty of the paper stems from the model applied that calculates the levelized cost of renewable hydrogen in an off-grid hydrogen production system. The model finds a cost-efficient portfolio of directly coupled wind power and solar photovoltaics systems for 80 different variants in an Austria-specific context.
Subsurface Porous Media Hydrogen Storage - Scenario Development and Simulation
Aug 2015
Publication
Subsurface porous media hydrogen storage could be a viable option to mitigate shortages in energy supply from renewable sources. In this work a scenario for such a storage is developed and the operation is simulated using a numerical model. A hypothetical storage site is developed based on an actual geological structure. The results of the simulations show that the storage can supply about 20 % of the average demand in electrical energy of the state of Schleswig-Holstein Germany for a week-long period.
Energy Management of Hydrogen Hybrid Electric Vehicles - A Potential Analysis
Jan 2024
Publication
The hydrogen combustion engine (H2 ICE) is known to be able to burn H2 producing no CO2 emissions and extremely low engine-out NOeo emissions. In this work the potential to reduce the NOeo emissions through the implementation of electric hybridization of an H2 ICE-equipped passenger car (H2 -HEV) combined with a dedicated energy management system (EMS) is discussed. Achieving a low H2 consumption and low NOeo emissions are conflicting objectives the trade-off of which depends on the EMS and can be represented as a Pareto front. The dynamic programming algorithm is used to calculate the Pareto-optimal EMS calibrations for various driving missions. Through the utilization of a dedicated energy management calibration H2 -HEVs exhibit the potential to decrease the NOeo x emissions by more than 90% while decreasing the H2 consumption by over 16% compared to a comparable non-hybridized H2 -vehicle. The present paper represents the initial potential analysis suggesting that H2 -HEVs are a viable option towards a CO2 -free mobility with extremely low NOeo emissions.
Pathways to the Hydrogen Economy: A Multidimensional Analysis of the Technological Innovation Systems of Germany and South Korea
Aug 2023
Publication
The global trend towards decarbonization and the demand for energy security have put hydrogen energy into the spotlight of industry politics and societies. Numerous governments worldwide are adopting policies and strategies to facilitate the transition towards hydrogen-based economies. To assess the determinants of such transition this study presents a comparative analysis of the technological innovation systems (TISs) for hydrogen technologies in Germany and South Korea both recognized as global front-runners in advancing and implementing hydrogen-based solutions. By providing a multi-dimensional assessment of pathways to the hydrogen economy our analysis introduces two novel and crucial elements to the TIS analysis: (i) We integrate the concept of ‘quality infrastructure’ given the relevance of safety and quality assurance for technology adoption and social acceptance and (ii) we emphasize the social perspective within the hydrogen TIS. To this end we conducted 24 semi-structured expert interviews applying qualitative open coding to analyze the data. Our results indicate that the hydrogen TISs in both countries have undergone significant developments across various dimensions. However several barriers still hinder the further realization of a hydrogen economy. Based on our findings we propose policy implications that can facilitate informed policy decisions for a successful hydrogen transition.
The Role of Hydrogen for a Greenhouse Gas-neutral Germany by 2045
May 2023
Publication
This paper aims to provide a holistic analysis of the role of hydrogen for achieving greenhouse gas neutrality in Germany. For that purpose we apply an integrated energy system model which includes all demand sectors of the German energy system and optimizes the transformation pathway from today's energy system to a future cost-optimal energy system. We show that 412 TWh of hydrogen are needed in the year 2045 mostly in the industry and transport sector. Particularly the use of about 267 TWh of hydrogen in industry is essential as there are no cost-effective alternatives for the required emission reduction in the chemical industry or in steel production. Furthermore we illustrate that the German hydrogen supply in the year 2045 requires both an expansion of domestic electrolyzer capacity to 71 GWH2 and hydrogen imports from other European countries and Northern Africa of about 196 TWh. Moreover flexible operation of electrolyzers is cost-optimal and crucial for balancing the intermittent nature of volatile renewable energy sources. Additionally a conducted sensitivity analysis shows that full domestic hydrogen supply in Germany is possible but requires an electrolyzer capacity of 111 GWH2.
Green Hydrogen Production: Integrating Environmental and Social Criteria to Ensure Sustainability
Jul 2023
Publication
Hydrogen is experiencing an unprecedented global hype. Hydrogen is globally discussed as a possible future energy carrier and regarded as the urgently needed building block for the much needed carbon-neutral energy transition of hard-to-abate sectors to mitigate the effects of global warming. This article provides synthesised measurable sustainability criteria for analysing green hydrogen production proposals and strategies. Drawn from expert interviews and an extensive literature review this article proposes that a sustainable hydrogen production should consider six impact categories; Energy transition Environment Basic needs Socio-economy Electricity supply and Project planning. The categories are broken down into sixteen measurable sustainability criteria which are determined with related indicators. The article concludes that low economic costs can never be the only decisive criterion for the hydrogen production; social aspects must be integrated along the entire value chain. The compliance with the criteria may avoid social and ecological injustices in the planning of green hydrogen projects and increases inter alia the social welfare of the affected population.
What Does the Public Know About Technological Solutions for Achieving Carbon Neutrality? Citizens' Knowledge of Energy Transition and the Role of Media
Aug 2023
Publication
The present study explores the relation between media use and knowledge in the context of the energy transition. To identify relevant knowledge categories we relied on the expertise of an interdisciplinary research team. Based on this expertise we identified awareness-knowledge of changes in the energy system and principles-knowledge of hydrogen as important knowledge categories. With data obtained from a nationwide online survey of the German-speaking population (n = 2025) conducted in August 2021 we examined the level of knowledge concerning both categories in the German population. Furthermore we studied its associations with exposure to journalistic media and direct communication from non-media actors (e.g. scientists). Our results revealed a considerable lack of knowledge for both categories. Considering the media variables we found only weak and in some cases even negative relations with the use of journalistic media or other actors that spread information online. However we found comparably strong associations between both knowledge categories and the control variables of sex education and personal interest. We use these results to open up a general discussion of the role of the media in knowledge acquisition processes.
Environmental and Material Criticality Assessment of Hydrogen Production via Anion Exchange Membrane Electrolysis
Oct 2023
Publication
The need to drastically reduce greenhouse gas emissions is driving the development of existing and new technologies to produce and use hydrogen. Anion exchange membrane electrolysis is one of these rapidly developing technologies and presents promising characteristics for efficient hydrogen production. However the environmental performance and the material criticality of anion exchange membrane electrolysis must be assessed. In this work prospective life cycle assessment and criticality assessment are applied first to identify environmental and material criticality hotspots within the production of anion exchange membrane electrolysis units and second to benchmark hydrogen production against proton exchange membrane electrolysis. From an environmental point of view the catalyst spraying process heavily dominates the ozone depletion impact category while the production of the membrane represents a hotspot in terms of the photochemical ozone formation potential. For the other categories the environmental impacts are distributed across different components. The comparison of hydrogen production via anion exchange membrane electrolysis and proton exchange membrane electrolysis shows that both technologies involve a similar life-cycle environmental profile due to similar efficiencies and the leading role of electricity generation for the operation of electrolysis. Despite the fact that for proton exchange membrane electrolysis much less material is required due to a higher lifetime anion exchange membrane electrolysis shows significantly lower raw material criticality since it does not rely on platinum-group metals. Overall a promising environmental and material criticality performance of anion exchange membrane electrolysis for hydrogen production is concluded subject to the expected technical progress for this technology.
Evaluation of the Impact of Gaseous Hydrogen on Pipeline Steels Utilizing Hollow Specimen Technique and μCT
Feb 2024
Publication
The high potential of hydrogen as a key factor on the pathway towards a climate neutral economy leads to rising demand in technical applications where gaseous hydrogen is used. For several metals hydrogen-metal interactions could cause a degradation of the material properties. This is especially valid for low carbon and highstrength structural steels as they are commonly used in natural gas pipelines and analyzed in this work. This work provides an insight to the impact of hydrogen on the mechanical properties of an API 5L X65 pipeline steel tested in 60 bar gaseous hydrogen atmosphere. The analyses were performed using the hollow specimen technique with slow strain rate testing (SSRT). The nature of the crack was visualized thereafter utilizing μCT imaging of the sample pressurized with gaseous hydrogen in comparison to one tested in an inert atmosphere. The combination of the results from non-conventional mechanical testing procedures and nondestructive imaging techniques has shown unambiguously how the exposure to hydrogen under realistic service pressure influences the mechanical properties of the material and the appearance of failure.
Regional Capabilities and Hydrogen Adoption Barriers
Dec 2023
Publication
Hydrogen is gaining importance to decarbonize the energy system and tackle the climate crisis. This exploratory study analyzes three focus groups with representatives from relevant organizations in a Northern German region that has unique beneficial characteristics for the transition to a hydrogen economy. Based upon this data (1) a category system of innovation adoption barriers for hydrogen technologies is developed (2) decision levels associated with the barriers are identified (3) detailed insights on how decision levels contribute to the adoption barriers are provided and (4) the barriers are evaluated in terms of their importance. Our analysis adds to existing literature by focusing on short-term barriers and exploring relevant decision levels and their associated adoption barriers. Our main results comprise the following: flaws in the funding system complex approval procedures lack of networks and high costs contribute to hydrogen adoption barriers. The (Sub-)State level is relevant for the uptake of the hydrogen economy. Regional entities have leeway to foster the hydrogen transition especially with respect to the distribution infrastructure. Funding policy technological suitability investment and operating costs and the availability of distribution infrastructure and technical components are highly important adoption barriers that alone can impede the transition to a hydrogen economy.
Natural Hydrogen in the Energy Transition: Fundamentals, Promise, and Enigmas
Oct 2023
Publication
Beyond its role as an energy vector a growing number of natural hydrogen sources and reservoirs are being discovered all over the globe which could represent a clean energy source. Although the hydrogen amounts in reservoirs are uncertain they could be vast and they could help decarbonize energy-intensive economic sectors and facilitate the energy transition. Natural hydrogen is mainly produced through a geochemical process known as serpentinization which involves the reaction of water with low-silica ferrous minerals. In favorable locations the hydrogen produced can become trapped by impermeable rocks on its way to the atmosphere forming a reservoir. The safe exploitation of numerous natural hydrogen reservoirs seems feasible with current technology and several demonstration plants are being commissioned. Natural hydrogen may show variable composition and require custom separation purification storage and distribution facilities depending on the location and intended use. By investing in research in the mid-term more hydrogen sources could become exploitable and geochemical processes could be artificially stimulated in new locations. In the long term it may be possible to leverage or engineer the interplay between microorganisms and geological substrates to obtain hydrogen and other chemicals in a sustainable manner.
Blue Hydrogen and Industrial Base Products: The Future of Fossil Fuel Exporters in a Net-zero World
May 2022
Publication
Is there a place for today’s fossil fuel exporters in a low-carbon future? This study explores trade channels between energy exporters and importers using a novel electricity-hydrogen-steel energy systems model calibrated to Norway a major natural gas producer and Germany a major energy consumer. Under tight emission constraints Norway can supply Germany with electricity (blue) hydrogen or natural gas with re-import of captured CO2. Alternatively it can use hydrogen to produce steel through direct reduction and supply it to the world market an export route not available to other energy carriers due to high transport costs. Although results show that natural gas imports with CO2 capture in Germany is the least-cost solution avoiding local CO2 handling via imports of blue hydrogen (direct or embodied in steel) involves only moderately higher costs. A robust hydrogen demand would allow Norway to profitably export all its natural gas production as blue hydrogen. However diversification into local steel production as one example of easy-to-export industrial base products offers an effective hedge against the possibility of lower European blue hydrogen demand. Looking beyond Europe the findings of this study are also relevant for the world’s largest energy exporters (e.g. OPEC+) and importers (e.g. developing Asia). Thus it is recommended that large hydrocarbon exporters consider a strategic energy export transition to a diversified mix of blue hydrogen and climate-neutral industrial base products.
Techno-economic Analysis of Underground Hydrogen Storage in Europe
Dec 2023
Publication
Hydrogen storage is crucial to developing secure renewable energy systems to meet the European Union’s 2050 carbon neutrality objectives. However a knowledge gap exists concerning the site-specific performance and economic viability of utilizing underground gas storage (UGS) sites for hydrogen storage in Europe. We compile information on European UGS sites to assess potential hydrogen storage capacity and evaluate the associated current and future costs. The total hydrogen storage potential in Europe is 349 TWh of working gas energy (WGE) with site-specific capital costs ranging from $10 million to $1 billion. Porous media and salt caverns boasting a minimum storage capacity of 0.5 TWh WGE exhibit levelized costs of $1.5 and $0.8 per kilogram of hydrogen respectively. It is estimated that future levelized costs associated with hydrogen storage can potentially decrease to as low as $0.4 per kilogram after three experience cycles. Leveraging these techno-economic considerations we identify suitable storage sites.
Regime-driven Niches and Institutional Entrepreneurs: Adding Hydrogen to Regional Energy Systems in Germany
Nov 2023
Publication
In recent years production and supply of hydrogen has gained significant attention within the German energy transition. This is due to increasingly urgent pressures to mitigate climate change and geopolitical imperatives to substitute natural gas. Hydrogen is seen as an important cross-sectoral energy carrier serving multiple functions including heat production for industry and households fuel for transportation and energy storage for stabilization of electricity supply. In the context of various funding mechanisms on several administrative levels regional value chains for green hydrogen supply are emerging. To date however few studies analyzing regional hydrogen systems exist. Due to its high projected demand of energy sources for heating industrial processes and mobility Germany appears to be a very relevant research area in this emerging field. Situated within the concept of the multi-level perspective this article examines the way how regional “niches” of green hydrogen evolve and how they are organized. The study takes an evolutionary perspective in analyzing processes of embedding green hydrogen infrastructures in regional energy regimes which entered “re-configuration”-pathways. It argues that the congruence of available resources for renewable electricity established networks of institutional entrepreneurs and access to higher level funding are conditions which put incumbent regime-actors in favorable positions to implement green hydrogen niches. Conversely the embedding of green hydrogen infrastructures in regional energy systems is a case in point of how the attributes of niches in particular technological domains can be used to explain the transition pathway entered by a surrounding energy regime.
3D Modeling of the Different Boiling Regimes During Spill and Spreading of Liquid Hydrogen
Nov 2012
Publication
In a future energy generation market the storage of energy is going to become increasingly important. Besides classic ways of storage like pumped storage hydro power stations etc the production of hydrogen will play an important role as an energy storage system. Hydrogen may be stored as a liquefied gas (LH2) on a long term base as well as for short term supply of fuel stations to ensure a so called “green” mobility. The handling with LH2 has been subject to several recent safety studies. In this context reliable simulation tools are necessary to predict the spill and spreading of LH2 during an accidental release. This paper deals with the different boiling regimes: film boiling transition boiling and nucleation boiling after a release and their modeling by means of an inhouse-code for wall evaporation which is implemented in the commercial CFD code ANSYS CFX. The paper will describe the model its implementation and validation against experimental data such as the HSL LH2 spill experiments.
Potential-risk and No-regret Options for Urban Energy System Design - A Sensitivity Analysis
Jan 2024
Publication
This study identifies supply options for sustainable urban energy systems which are robust to external system changes. A multi-criteria optimization model is used to minimize greenhouse gas (GHG) emissions and financial costs of a reference system. Sensitivity analyses examine the impact of changing boundary conditions related to GHG emissions energy prices energy demands and population density. Options that align with both financial and emission reduction and are robust to system changes are called “no-regret” options. Options sensitive to system changes are labeled as “potential-risk” options.<br/>There is a conflict between minimizing GHG emissions and financial costs. In the reference case the emission-optimized scenario enables a reduction of GHG emissions (-93%) but involves higher costs (+160%) compared to the financially-optimized scenario.<br/>No-regret options include photovoltaic systems decentralized heat pumps thermal storages electricity exchange between sub-systems and with higher-level systems and reducing energy demands through building insulation behavioral changes or the decrease of living space per inhabitant. Potential-risk options include solar thermal systems natural gas technologies high-capacity battery storages and hydrogen for buildiing energy supply.<br/>When energy prices rise financially-optimized systems approach the least-emission system design. The maximum profitability of natural gas technologies was already reached before the 2022 European energy crisis.
Experimental Evaluation of Dynamic Operating Concepts for Alkaline Water Electrolyzers Powered by Renewable Energy
Dec 2021
Publication
Synthetic current density profiles with wind and photovoltaic power characteristics were calculated by autoregressive-moving-average (ARMA) models for the experimental evaluation of dynamic operating concepts for alkaline water electrolyzers powered by renewable energy. The selected operating concepts included switching between mixed and split electrolyte cycles and adapting the liquid electrolyte volume flow rate depending on the current density. All experiments were carried out at a pressure of 7 bar a temperature of 60 °C and with an aqueous potassium hydroxide solution with 32 wt.% KOH as the electrolyte. The dynamic operating concepts were compared to stationary experiments with mixed electrolyte cycles and the experimental evaluation showed that the selected operating concepts were able to reduce the gas impurity compared to the reference operating conditions without a noticeable increase of the cell potential. Therefore the overall system efficiency and process safety could be enhanced by this approach.
Hydrogen Storage Capacity of Salt Caverns and Deep Aquifers Versus Demand for Hydrogen Storage: A Case Study of Poland
Nov 2023
Publication
Geological structures in deep aquifers and salt caverns can play an important role in large-scale hydrogen storage. However more work needs to be done to address the hydrogen storage demand for zero-emission energy systems. Thus the aim of the article is to present the demand for hydrogen storage expressed in the number of salt caverns in bedded rock salt deposits and salt domes or the number of structures in deep aquifers. The analysis considers minimum and maximum hydrogen demand cases depending on future energy system configurations in 2050. The method used included the estimation of the storage capacity of salt caverns in bedded rock salt deposits and salt domes and selected structures in deep aquifers. An estimation showed a large hydrogen storage potential of geological structures. In the case of analyzed bedded rock salt deposits and salt domes the average storage capacity per cavern is 0.05–0.09 TWhH2 and 0.06–0.20 TWhH2 respectively. Hydrogen storage capacity in analyzed deep aquifers ranges from 0.016 to 4.46 TWhH2. These values indicate that in the case of the upper bound for storage demand there is a need for the 62 to 514 caverns depending on considered bedded rock salt deposits and salt domes or the 9 largest analyzed structures in deep aquifers. The results obtained are relevant to the discussion on the global hydrogen economy and the methodology can be used for similar considerations in other countries.
The Race Between Hydrogen and Heat Pumps for Space and Water Heating: A Model-based Scenario Analysis
Nov 2023
Publication
This paper analyses different levels and means of the electrification of space and hot water heating using an explorative modelling approach. The analysis provides guidance to the ongoing discussion on favourable pathways for heating buildings and the role of secondary energy carriers such as hydrogen or synthetic fuels. In total 12 different scenarios were modelled with decarbonisation pathways until 2050 which cover all 27 member states of the European Union. Two highly detailed optimisation models were combined to cover the building stock and the upstream energy supply sector. The analysis shows that decarbonisation pathways for space and water heating based on large shares of heat pumps have at least 11% lower system costs in 2050 than pathways with large shares of hydrogen or synthetic fuels. This translates into system cost savings of around €70 bn. Heat pumps are cost-efficient in decentralised systems and in centralised district heating systems. Hence heat pumps should be the favoured option to achieve a cost-optimal solution for heating buildings. Accordingly the paper makes a novel and significant contribution to understanding suitable and cost-efficient decarbonisation pathways for space and hot water heating via electrification. The results of the paper can provide robust guidance for policymakers.
Comparative Life Cycle Assessment of Battery and Fuel Cell Electric Cars, Trucks, and Buses
Mar 2024
Publication
Addressing the pressing challenge of global warming reducing greenhouse gas emissions in the transportation sector is a critical imperative. Battery and fuel cell electric vehicles have emerged as promising solutions for curbing emissions in this sector. In this study we conducted a comprehensive life cycle assessment (LCA) for typical passenger vehicles heavy-duty trucks and city buses using either proton-exchange membrane fuel cells or Li-ion batteries with different cell chemistries. To ensure accuracy we supplemented existing studies with data from the literature particularly for the recycling phase as database limitations were encountered. Our results highlight that fuel cell and battery systems exhibit large emissions in the production phase. Recycling can significantly offset some of these emissions but a comparison of the technologies examined revealed considerable differences. Overall battery electric vehicles consistently outperform fuel cell electric vehicles regarding absolute greenhouse gas emissions. Hence we recommend prioritizing battery electric over fuel cell vehicles. However deploying fuel cell electric vehicles could become attractive in a hydrogen economy scenario where other factors e. g. the conversion and storage of surplus renewable electricity via electrolysis become important.
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