Germany
Economic Analysis of Improved Alkaline Water Electrolysis
Feb 2017
Publication
Alkaline water electrolysis (AWE) is a mature hydrogen production technology and there exists a range of economic assessments for available technologies. For advanced AWEs which may be based on novel polymer-based membrane concepts it is of prime importance that development comes along with new configurations and technical and economic key process parameters for AWE that might be of interest for further economic assessments. This paper presents an advanced AWE technology referring to three different sites in Europe (Germany Austria and Spain). The focus is on financial metrics the projection of key performance parameters of advanced AWEs and further financial and tax parameters. For financial analysis from an investor’s (business) perspective a comprehensive assessment of a technology not only comprises cost analysis but also further financial analysis quantifying attractiveness and supply/market flexibility. Therefore based on cash flow (CF) analysis a comprehensible set of metrics may comprise levelised cost of energy or respectively levelized cost of hydrogen (LCH) for cost assessment net present value (NPV) for attractiveness analysis and variable cost (VC) for analysis of market flexibility. The German AWE site turns out to perform best in all three financial metrics (LCH NPV and VC). Though there are slight differences in investment cost and operation and maintenance cost projections for the three sites the major cost impact is due to the electricity cost. Although investment cost is slightly lower and labor cost is significantly lower in Spain the difference can not outweigh the higher electricity cost compared to Germany. Given the assumption that the electrolysis operators are customers directly and actively participating in power markets and based on the regulatory framework in the three countries in this special case electricity cost in Germany is lowest. However as electricity cost is profoundly influenced by political decisions as well as the implementation of economic instruments for transforming electricity systems toward sustainability it is hardly possible to further improve electricity price forecasts.
Mind the Gap—A Socio-Economic Analysis on Price Developments of Green Hydrogen, Synthetic Fuels, and Conventional Energy Carriers in Germany
May 2022
Publication
In recent years the development of energy prices in Germany has been frequently accompanied by criticism and warnings of socio-economic disruptions. Especially with respect to the electricity sector the debate on increasing energy bills was strongly correlated with the energy system transition. However whereas fossil fuels have rapidly increased in price recently renewable substitutes such as green hydrogen and synthetic fuels also enter the markets at comparatively high prices. On the other hand the present fossil fuel supply is still considered too low-priced by experts because societal greenhouse gas-induced environmental impact costs are not yet compensated. In this study we investigate the development of the price gap between conventional energy carriers and their renewable substitutes until 2050 as well as a suitable benchmark price incorporating the societal costs of specific energy carriers. The calculated benchmark prices for natural gas (6.3 ct kWh−1 ) petrol (9.9 ct kWh−1 ) and grey hydrogen from steam methane reformation (12 ct kWh−1 ) are nearly 300% above the actual prices for industry customers in 2020 but below the price peaks of early 2022. In addition the price gap between conventional fuels and green hydrogen will be completely closed before 2050 for all investigated energy carriers. Furthermore prognosed future price developments can be considered rather moderate compared to historic and especially to the recent price dynamics in real terms. A gradual implementation of green hydrogen and synthetic fuels next to increasing CO2 prices however may temporarily lead to further increasing expenses for energy but can achieve lower price levels comparable to those of 2020 in the long term.
Sustainability Assessment of Fuel Cell Buses in Public Transport
May 2018
Publication
Hydrogen fuel cell (H2FC) buses operating in every day public transport services around Europe are assessed for their sustainability against environmental economic and social criteria. As part of this assessment the buses are evaluated against diesel buses both in terms of sustainability and in terms of meeting real world requirements with respect to operational performance. The study concludes that H2FC buses meet operability and performance criteria and are sustainable environmentally when ‘green’ hydrogen is used. The economic sustainability of the buses in terms of affordability achieves parity with their fossil fuel equivalent by 2030 when the indirect costs to human health and climate change are included. Societal acceptance by those who worked with and used the buses supports the positive findings of earlier studies although satisfactory operability and performance are shown to be essential to positive attitudes. Influential policy makers expressed positive sentiments only if ‘green’ hydrogen is used and the affordability issues can be addressed. No “show-stopper” is identified that would prevent future generations from using H2FC buses in public transport on a broad scale due to damage to the environment or to other factors that impinge on quality of life.
Potential of New Business Models for Grid Integrated Water Electrolysis
Feb 2018
Publication
Grid integrated water electrolysers have the potential of coupling electric power systems subjected to high shares of renewable energy sources with sectors of hydrogen demand thus contributing to European decarbonization goals in future. We therefore investigate the business potential of future electrolyser applications in cross-commodity arbitrage trading by applying a complex power market simulation method for future scenarios and different European countries. Based on this we evaluate the potential of additional provision of grid services towards grid operators in order to increase the electrolyser utilization ratio. For this we use a method that identifies measures of transmission grid operators in order to ensure secure grid operation. In this context uncertain hydrogen prices and different sectors of hydrogen demand are addressed through sensitivities of different hydrogen sales prices. The analysis shows a high dependency of business model efficiency on the hydrogen price. While cross-commodity arbitrage trading can achieve profitability for the transportation sector applications for the industry sector and natural gas system are less efficient. The results however indicate that for these less efficient applications grid service provision can be an option of increasing the electrolyser utilization ratio thus increasing its profitability.
Experimental Investigation on the Burning Behavior of Homogenous H2-CO-Air Mixtures in an Obstructed Semi-confined Channel
Sep 2021
Publication
In the current work the combustion behavior of hydrogen-carbon monoxide-air mixtures in semiconfined geometries is investigated in a large horizontal channel facility (dimensions 9 m x 3 m x 0.6 m (L x W x H)) as a part of a joint German nuclear safety project. In the channel with evenly distributed obstacles (blockage ratio 50%) and an open to air ground face homogeneous H2-CO-air mixtures are ignited at one end. The combustion behavior of the mixture is analyzed using the signals of pressure sensors modified thermocouples and ionization probes for flame front detection that are distributed along the channel ceiling. In the experiments various fuel concentrations (cH2 + cCO = 14 to 22 Vol%) with different H2:CO ratios (75:25 50:50 and 25:75) are used and the transition regions for a significant flame acceleration to sonic speed (FA) as well as to a detonation (DDT) are investigated. The conditions for the onset of these transitions are compared with earlier experiments performed in the same facility with H2-air mixtures. The results of this work will help to allow a more realistic estimation of the pressure loads generated by the combustion of H2-CO-air mixtures in obstructed semi-confined geometries.
Hydrogen Blowdown Release Experiments at Different Temperatures in the Discha-facility
Sep 2021
Publication
In this work experiments on horizontal hydrogen jet releases from a 2.815 dm³ volume tank to the ambience are described. For the main experimental series tank valve and release line were cooled down to a temperature of approx. 80 K in a bath of liquid nitrogen. As a reference similar experiments were also performed with the uncooled tank at ambient temperature. The releases were carried out through four nozzles with different circular orifice diameters from 0.5 to 4 mm and started from initial tank pressures from 0.5 to 20 MPa (rel.). During the releases pressures and temperatures inside the vessel as well as inside the release line were measured. Outside the nozzle further temperature and hydrogen concentration measurements were performed along and besides the jet axis. The electrostatic field builtup in the jet was monitored using two field meters in different distances from the release nozzle and optical observation via photo and video-cameras was performed for the visualization of the H2-jet via the BOS-method. The experiments were performed in the frame of the EU-funded project PRESHLY in which several tests of this program were selected for a comparative computational study the results of which will also be presented at this conference. So on the one hand the paper gives a comprehensive description of the facility on the other hands it also describes the experimental procedure and the main findings.
Ammonia Production from Clean Hydrogen and the Implications for Global Natural Gas Demand
Jan 2023
Publication
Non-energy use of natural gas is gaining importance. Gas used for 183 million tons annual ammonia production represents 4% of total global gas supply. 1.5-degree pathways estimate an ammonia demand growth of 3–4-fold until 2050 as new markets in hydrogen transport shipping and power generation emerge. Ammonia production from hydrogen produced via water electrolysis with renewable power (green ammonia) and from natural gas with CO2 storage (blue ammonia) is gaining attention due to the potential role of ammonia in decarbonizing energy value chains and aiding nations in achieving their net-zero targets. This study assesses the technical and economic viability of different routes of ammonia production with an emphasis on a systems level perspective and related process integration. Additional cost reductions may be driven by optimum sizing of renewable power capacity reducing losses in the value chain technology learning and scale-up reducing risk and a lower cost of capital. Developing certification and standards will be necessary to ascertain the extent of greenhouse gas emissions throughout the supply chain as well as improving the enabling conditions including innovative finance and de-risking for facilitating international trade market creation and large-scale project development.
Study of the Microstructural and First Hydrogenation Properties of TiFe Alloy with Zr, Mn and V as Additives
Jul 2021
Publication
In this paper we report the effect of adding Zr + V or Zr + V + Mn to TiFe alloy on microstructure and hydrogen storage properties. The addition of only V was not enough to produce a minimum amount of secondary phase and therefore the first hydrogenation at room temperature under a hydrogen pressure of 20 bars was impossible. When 2 wt.% Zr + 2 wt.% V or 2 wt.% Zr + 2 wt.% V + 2 wt.% Mn is added to TiFe the alloy shows a finely distributed Ti2Fe-like secondary phase. These alloys presented a fast first hydrogenation and a high capacity. The rate-limiting step was found to be 3D growth diffusion controlled with decreasing interface velocity. This is consistent with the hypothesis that the fast reaction is likely to be the presence of Ti2Fe-like secondary phases that act as a gateway for hydrogen.
Simulation of a Hydrogen-Air Diffusion Flame under Consideration of Component-Specific Diffusivities
Mar 2022
Publication
This work deals with the numerical investigation of a three-dimensional laminar hydrogenair diffusion flame in which a cylindrical fuel jet is surrounded by in-flowing air. To calculate the distribution of gas molecules the model solves the species conservation equation for N-1 components using infinity fast chemistry and irreversible chemical reaction. The consideration of the component-specific diffusion has a strong influence on the position of the high-temperature zone as well as on the concentration distribution of the individual gas molecules. The calculations of the developed model predict the radial and axial species and temperature distribution in the combustion chamber comparable to those from previous publications. Deviations due to a changed burner geometry and air supply narrow the flame structure by up to 50% and the high-temperature zones merge toward the central axis. Due to the reduced inflow velocity of the hydrogen the high-temperature zones develop closer to the nozzle inlet of the combustion chamber. As the power increases the length of the cold hydrogen jet increases. Furthermore the results show that the axial profiles of temperature and mass fractions scale quantitatively with the power input by the fuel.
Deployment of Fuel Cell Vehicles and Hydrogen Refueling Station Infrastructure: A Global Overview and Perspectives
Jul 2022
Publication
Hydrogen fuel cell vehicles can complement other electric vehicle technologies as a zeroemission technology and contribute to global efforts to achieve the emission reduction targets. This article spotlights the current deployment status of fuel cells in road transport. For this purpose data collection was performed by the Advanced Fuel Cells Technology Collaboration Programme. Moreover the available incentives for purchasing a fuel cell vehicle in different countries were reviewed and future perspectives summarized. Based on the collected information the development trends in the last five years were analyzed and possible further trends that could see the realization of the defined goals derived. The number of registered vehicles was estimated to be 51437 units with South Korea leading the market with 90% of the vehicles being concentrated in four countries. A total of 729 hydrogen refueling stations were in operation with Japan having the highest number of these. The analysis results clearly indicate a very positive development trend for fuel cell vehicles and hydrogen refueling stations in 2021 with the highest number of new vehicles and stations in a single year paralleling the year’s overall economic recovery. Yet a more ambitious ramp-up in the coming years is required to achieve the set targets.
On the Climate Impacts of Blue Hydrogen Production
Nov 2021
Publication
Natural gas based hydrogen production with carbon capture and storage is referred to as blue hydrogen. If substantial amounts of CO2 from natural gas reforming are captured and permanently stored such hydrogen could be a low-carbon energy carrier. However recent research raises questions about the effective climate impacts of blue hydrogen from a life cycle perspective. Our analysis sheds light on the relevant issues and provides a balanced perspective on the impacts on climate change associated with blue hydrogen. We show that such impacts may indeed vary over large ranges and depend on only a few key parameters: the methane emission rate of the natural gas supply chain the CO2 removal rate at the hydrogen production plant and the global warming metric applied. State-of-the-art reforming with high CO2 capture rates combined with natural gas supply featuring low methane emissions does indeed allow for substantial reduction of greenhouse gas emissions compared to both conventional natural gas reforming and direct combustion of natural gas. Under such conditions blue hydrogen is compatible with low-carbon economies and exhibits climate change impacts at the upper end of the range of those caused by hydrogen production from renewable-based electricity. However neither current blue nor green hydrogen production pathways render fully “net-zero” hydrogen without additional CO2 removal.
Climate Impact Reduction Potentials of Synthetic Kerosene and Green Hydrogen Powered Mid-Range Aircraft Concepts
Jun 2022
Publication
One of aviation’s major challenges for the upcoming decades is the reduction in its climate impact. As synthetic kerosene and green hydrogen are two promising candidates their potentials in decreasing the climate impact is investigated for the mid-range segment. Evolutionary advancements for 2040 are applied first with an conventional and second with an advanced low-NOx and low-soot combustion chamber. Experts and methods from all relevant disciplines are involved starting from combustion turbofan engine overall aircraft design fleet level and climate impact assessment allowing a sophisticated and holistic evaluation. The main takeaway is that both energy carriers have the potential to strongly reduce the fleet level climate impact by more than 75% compared with the reference. Applying a flight-level constraint of 290 and a cruise Mach number of 0.75 causing 5% higher average Direct Operating Costs (DOC) the reduction is even more than 85%. The main levers to achieve this are the advanced combustion chamber an efficient contrail avoidance strategy in this case a pure flight-level constraint and the use of CO2 neutral energy carrier in a descending priority order. Although vehicle efficiency gains only lead to rather low impact reduction they are very important to compensate the increased costs of synthetic fuels or green hydrogen.
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.
Solid-State Hydrogen Storage for a Decarbonized Society
Nov 2021
Publication
Humanity is confronted with one of the most significant challenges in its history. The excessive use of fossil fuel energy sources is causing extreme climate change which threatens our way of life and poses huge social and technological problems. It is imperative to look for alternate energy sources that can replace environmentally destructive fossil fuels. In this scenario hydrogen is seen as a potential energy vector capable of enabling the better and synergic exploitation of renewable energy sources. A brief review of the use of hydrogen as a tool for decarbonizing our society is given in this work. Special emphasis is placed on the possibility of storing hydrogen in solid-state form (in hydride species) on the potential fields of application of solid-state hydrogen storage and on the technological challenges solid-state hydrogen storage faces. A potential approach to reduce the carbon footprint of hydrogen storage materials is presented in the concluding section of this paper.
Boosting the H2 Production Efficiency via Photocatalytic Organic Reforming: The Role of Additional Hole Scavenging System
Nov 2021
Publication
The simultaneous photocatalytic H2 evolution with environmental remediation over semiconducting metal oxides is a fascinating process for sustainable fuel production. However most of the previously reported photocatalytic reforming showed nonstoichiometric amounts of the evolved H2 when organic substrates were used. To explain the reasons for this phenomenon a careful analysis of the products and intermediates in gas and aqueous phases upon the photocatalytic hydrogen evolution from oxalic acid using Pt/TiO2 was performed. A quadrupole mass spectrometer (QMS) was used for the continuous flow monitoring of the evolved gases while high performance ion chromatography (HPIC) isotopic labeling and electron paramagnetic resonance (EPR) were employed to understand the reactions in the solution. The entire consumption of oxalic acid led to a ~30% lower H2 amount than theoretically expected. Due to the contribution of the photoKolbe reaction mechanism a tiny amount of formic acid was produced then disappeared shortly after the complete consumption of oxalic acid. Nevertheless a much lower concentration of formic acid was generated compared to the nonstoichiometric difference between the formed H2 and the consumed oxalic acid. Isotopic labeling measurements showed that the evolved H2 HD and/or D2 matched those of the solvent; however using D2O decreased the reaction rate. Interestingly the presence of KI as an additional hole scavenger with oxalic acid had a considerable impact on the reaction mechanism and thus the hydrogen yield as indicated by the QMS and the EPR measurements. The added KI promoted H2 evolution to reach the theoretically predictable amount and inhibited the formation of intermediates without affecting the oxalic acid degradation rate. The proposed mechanism by which KI boosts the photocatalytic performance is of great importance in enhancing the overall energy efficiency for hydrogen production via photocatalytic organic reforming.
Artificial Intelligence-Based Machine Learning toward the Solution of Climate-Friendly Hydrogen Fuel Cell Electric Vehicles
Jul 2022
Publication
The rapid conversion of conventional powertrain technologies to climate-neutral new energy vehicles requires the ramping of electrification. The popularity of fuel cell electric vehicles with improved fuel economy has raised great attention for many years. Their use of green hydrogen is proposed to be a promising clean way to fill the energy gap and maintain a zero-emission ecosystem. Their complex architecture is influenced by complex multiphysics interactions driving patterns and environmental conditions that put a multitude of power requirements and boundary conditions around the vehicle subsystems including the fuel cell system the electric motor battery and the vehicle itself. Understanding its optimal fuel economy requires a systematic assessment of these interactions. Artificial intelligence-based machine learning methods have been emerging technologies showing great potential for accelerated data analysis and aid in a thorough understanding of complex systems. The present study investigates the fuel economy peaks during an NEDC in fuel cell electric vehicles. An innovative approach combining traditional multiphysics analyses design of experiments and machine learning is an effective blend for accelerated data supply and analysis that accurately predicts the fuel consumption peaks in fuel cell electric vehicles. The trained and validated models show very accurate results with less than 1% error.
Synergistic Value in Vertically Integrated Power-to-Gas Energy Systems
Oct 2019
Publication
In vertically integrated energy systems integration frequently entails operational gains that must be traded off against the requisite cost of capacity investments. In the context of the model analyzed in this study the operational gains are subject to inherent volatility in both the price and the output of the intermediate product transferred within the vertically integrated structure. Our model framework provides necessary and sufficient conditions for the value (NPV) of an integrated system to exceed the sum of two optimized subsystems on their own. We then calibrate the model in Germany and Texas for systems that combine wind energy with Power-to-Gas (PtG) facilities that produce hydrogen. Depending on the prices for hydrogen in different market segments we find that a synergistic investment value emerges in some settings. In the context of Texas for instance neither electricity generation from wind power nor hydrogen production from PtG is profitable on its own in the current market environment. Yet provided both subsystems are sized optimally in relative terms the attendant operational gains from vertical integration more than compensate for the stand-alone losses of the two subsystems.
Towards the Efficient and Time-accurate Simulations of Early Stages of Industrial Explosions
Sep 2021
Publication
Combustion during a nuclear reactor accident can result in pressure loads that are potentially fatal for the structural integrity of the reactor containment or its safety equipment. Enabling efficient modelling of such safety-critical scenarios is the goal of ongoing work. In this paper attention is given to capturing early phases of flame propagation. Transient simulations that are not prohibitively expensive for use at industrial scale are required given that a typical flame propagation study takes a large number of simulation time steps to complete. An improved numerical method used in this work is based on explicit time integration by means of Strong Stability Preserving (SSP) Runge-Kutta schemes. These allow an increased time step size for a given level of accuracy—reducing the overall computational effort. Furthermore a wide range of flow conditions is encountered in analysis of accelerating flames: from incompressible to potentially supersonic. In contrast numerical schemes for spatial discretization would often prove lacking in either stability or accuracy outside the intended flow regime—with density-based schemes being traditionally designed and applied to compressible (Ma>0.3) flows. In the present work a formulation of an all-speed density-based numerical flux scheme is used for simulation of slow flames starting from ignition. Validation was carried out using experiments with spherical lean hydrogen flames at laboratory scale. Turbulence conditions in the experiments correspond to those that can arise in a nuclear reactor containment during an accident. Results show that the new numerical method has the potential to predict flame speed and pressure rise at a reduced computational effort.
Current Legislative Framework for Green Hydrogen Production by Electrolysis Plants in Germany
Mar 2022
Publication
(1) The German energy system transformation towards an entirely renewable supply is expected to incorporate the extensive use of green hydrogen. This carbon-free fuel allows the decarbonization of end-use sectors such as industrial high-temperature processes or heavy-duty transport that remain challenging to be covered by green electricity only. However it remains unclear whether the current legislative framework supports green hydrogen production or is an obstacle to its rollout. (2) This work analyzes the relevant laws and ordinances regarding their implications on potential hydrogen production plant operators. (3) Due to unbundling-related constraints potential operators from the group of electricity transport system and distribution system operators face lacking permission to operate production plants. Moreover ownership remains forbidden for them. The same applies to natural gas transport system operators. The case is less clear for natural gas distribution system operators where explicit regulation is missing. (4) It is finally analyzed if the production of green hydrogen is currently supported in competition with fossil hydrogen production not only by the legal framework but also by the National Hydrogen Strategy and the Amendment of the Renewable Energies Act. It can be concluded that in recent amendments of German energy legislation regulatory support for green hydrogen in Germany was found. The latest legislation has clarified crucial points concerning the ownership and operation of electrolyzers and the treatment of green hydrogen as a renewable energy carrier.
Iron as Recyclable Energy Carrier: Feasibility Study and Kinetic Analysis of Iron Oxide Reduction
Oct 2022
Publication
Carbon-free and sustainable energy storage solutions are required to mitigate climate change. One possible solution especially for stationary applications could be the storage of energy in metal fuels. Energy can be stored through reduction of the oxide with green hydrogen and be released by combustion. In this work a feasibility study for iron as possible metal fuel considering the complete energy cycle is conducted. Based on equilibrium calculations it could be shown that the power-to-power efficiency of the iron/iron oxide cycle is 27 %. As technology development requires a more detailed description of both the reduction and the oxidation a first outlook is given on the kinetic analysis of the reduction of iron oxides with hydrogen. Based on thermogravimetric experiments using Fe2O3 Fe3O4 and FeO it could be shown that the reduction is a three-step process. The maximum reduction rate can be achieved with a hydrogen content of 25 %. Based on the experimental results a reaction mechanism and accompanied kinetic data were developed for description of Fe2O3 reduction with H2 under varying experimental conditions.
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