Germany
Overview of First Outcomes of PNR Project HYTUNNEL-CS
Sep 2021
Publication
Dmitry Makarov,
Donatella Cirrone,
Volodymyr V. Shentsov,
Sergii Kashkarov,
Vladimir V. Molkov,
Z. Xu,
Mike Kuznetsov,
Alexandros G. Venetsanos,
Stella G. Giannissi,
Ilias C. Tolias,
Knut Vaagsaether,
André Vagner Gaathaug,
Mark R. Pursell,
Wayne M. Rattigan,
Frank Markert,
Luisa Giuliani,
L.S. Sørensen,
A. Bernad,
Mercedes Sanz Millán,
U. Kummer,
Christian Brauner,
Paola Russo,
J. van den Berg,
F. de Jong,
Tom Van Esbroeck,
M. Van De Veire,
Didier Bouix,
Gilles Bernard-Michel,
Sergey Kudriakov,
Etienne Studer,
Domenico Ferrero,
Joachim Grüne and
G. Stern
The paper presents the first outcomes of the experimental numerical and theoretical studies performed in the funded by Fuel Cell and Hydrogen Joint Undertaking (FCH2 JU) project HyTunnel-CS. The project aims to conduct pre-normative research (PNR) to close relevant knowledge gaps and technological bottlenecks in the provision of safety of hydrogen vehicles in underground transportation systems. Pre normative research performed in the project will ultimately result in three main outputs: harmonised recommendations on response to hydrogen accidents recommendations for inherently safer use of hydrogen vehicles in underground traffic systems and recommendations for RCS. The overall concept behind this project is to use inter-disciplinary and inter-sectoral prenormative research by bringing together theoretical modelling and experimental studies to maximise the impact. The originality of the overall project concept is the consideration of hydrogen vehicle and underground traffic structure as a single system with integrated safety approach. The project strives to develop and offer safety strategies reducing or completely excluding hydrogen-specific risks to drivers passengers public and first responders in case of hydrogen vehicle accidents within the currently available infrastructure.
Import Options for Chemical Energy Carriers from Renewable Sources to Germany
Feb 2024
Publication
Import and export of fossil energy carriers are cornerstones of energy systems world-wide. If energy systems are to become climate neutral and sustainable fossil carriers need to be substituted with carbon neutral alternatives or electrified if possible. We investigate synthetic chemical energy carriers hydrogen methane methanol ammonia and Fischer-Tropsch fuels produced using electricity from Renewable Energy Source (RES) as fossil substitutes. RES potentials are obtained from GIS-analysis and hourly resolved time-series are derived using reanalysis weather data. We model the sourcing of feedstock chemicals synthesis and transport along nine different Energy Supply Chains to Germany and compare import options for seven locations around the world against each other and with domestically sourced alternatives on the basis of their respective cost per unit of hydrogen and energy delivered. We find that for each type of chemical energy carrier there is an import option with lower costs compared to domestic production in Germany. No single exporting country or energy carrier has a unique cost advantage since for each energy carrier and country there are cost-competitive alternatives. This allows exporter and infrastructure decisions to be made based on other criteria than energy and cost. The lowest cost means for importing of energy and hydrogen are by hydrogen pipeline from Denmark Spain and Western Asia and Northern Africa starting at 36 EUR/MWhLHV to 42 EUR/MWhLHV or 1.0 EUR/kgH2 to 1.3 EUR/kgH2 (in 2050 assuming 5% p.a. capital cost). For complex energy carriers derived from hydrogen like methane ammonia methanol or Fischer-Tropsch fuels imports from Argentina by ship to Germany are lower cost than closer exporters in the European Union or Western Asia and Northern Africa. For meeting hydrogen demand direct hydrogen imports are more attractive than indirect routes using methane methanol or ammonia imports and subsequent decomposition to hydrogen because of high capital investment costs and energetic losses of the indirect routes. We make our model and data available under open licenses for adaptation and reuse.
Underground Hydrogen Storage: Application of Geochemical Modelling in a Case Study in the Molasse Basin, Upper Austria
Feb 2019
Publication
Hydrogen storage in depleted gas fields is a promising option for the large-scale storage of excess renewable energy. In the framework of the hydrogen storage assessment for the “Underground Sun Storage” project we conduct a multi-step geochemical modelling approach to study fluid–rock interactions by means of equilibrium and kinetic batch simulations. With the equilibrium approach we estimate the long-term consequences of hydrogen storage whereas kinetic models are used to investigate the interactions between hydrogen and the formation on the time scales of typical storage cycles. The kinetic approach suggests that reactions of hydrogen with minerals become only relevant over timescales much longer than the considered storage cycles. The final kinetic model considers both mineral reactions and hydrogen dissolution to be kinetically controlled. Interactions among hydrogen and aqueous-phase components seem to be dominant within the storage-relevant time span. Additionally sensitivity analyses of hydrogen dissolution kinetics which we consider to be the controlling parameter of the overall reaction system were performed. Reliable data on the kinetic rates of mineral dissolution and precipitation reactions specifically in the presence of hydrogen are scarce and often not representative of the studied conditions. These uncertainties in the kinetic rates for minerals such as pyrite and pyrrhotite were investigated and are discussed in the present work. The proposed geochemical workflow provides valuable insight into controlling mechanisms and risk evaluation of hydrogen storage projects and may serve as a guideline for future investigations.
Assessing the Social Acceptance of Key Technologies for the German Energy Transition
Jan 2022
Publication
Background: The widespread use of sustainable energy technologies is a key element in the transformation of the energy system from fossil-based to zero-carbon. In line with this technology acceptance is of great importance as resistance from the public can slow down or hinder the construction of energy technology projects. The current study assesses the social acceptance of three energy technologies relevant for the German energy transition: stationary battery storage biofuel production plants and hydrogen fuel station. Methods: An online survey was conducted to examine the public’s general and local acceptance of energy technologies. Explored factors included general and local acceptance public concerns trust in relevant stakeholders and attitudes towards financial support. Results: The results indicate that general acceptance for all technologies is slightly higher than local acceptance. In addition we discuss which public concerns exist with regard to the respective technologies and how they are more strongly associated with local than general acceptance. Further we show that trust in stakeholders and attitudes towards fnancial support is relatively high across the technologies discussed. Conclusions: Taken together the study provides evidence for the existence of a “general–local” gap despite measuring general and local acceptance at the same level of specifcity using a public sample. In addition the collected data can provide stakeholders with an overview of worries that might need to be addressed when planning to implement a certain energy project.
Power-to-gas and the Consequences: Impact of Higher Hydrogen Concentrations in Natural Gas on Industrial Combustion Processes
Sep 2017
Publication
Operators of public electricity grids today are faced with the challenge of integrating increasing numbers of renewable and decentralized energy sources such as wind turbines and photovoltaic power plants into their grids. These sources produce electricity in a very inconstant manner due to the volatility of wind and solar power which further complicates power grid control and management. One key component that is required for modern energy infrastructures is the capacity to store large amounts of energy in an economically feasible way.<br/>One solution that is being discussed in this context is “power-to-gas” i.e. the use of surplus electricity to produce hydrogen (or even methane with an additional methanation process) which is then injected into the public natural gas grid. The huge storage capacity of the gas grid would serve as a buffer offering benefits with regards to sustainability and climate protection while also being cost-effective since the required infrastructure is already in place.<br/>One consequence would be however that the distributed natural gas could contain larger and fluctuating amounts of hydrogen. There is some uncertainty how different gas-fired applications and processes react to these changes. While there have already been several investigations for domestic appliances (generally finding that moderate amounts of H2 do not pose any safety risks which is the primary focus of domestic gas utilization) there are still open questions concerning large-scale industrial gas utilization. Here in addition to operational safety factors like efficiency pollutant emissions (NOX) process stability and of course product quality have to be taken into account.<br/>In a German research project Gas- und Wärme-Institut Essen e. V. (GWI) investigated the impact of higher and fluctuating hydrogen contents (up to 50 vol.-% much higher than what is currently envisioned) on a variety of industrial combustion systems using both numerical and experimental methods. The effects on operational aspects such as combustion behavior flame monitoring and pollutant emissions were analyzed.<br/>Some results of these investigations will be presented in this contribution.
Multi-Objective Optimization-Based Health-Conscious Predictive Energy Management Strategy for Fuel Cell Hybrid Electric Vehicles
Feb 2022
Publication
The Energy Management Strategy (EMS) in Fuel Cell Hybrid Electric Vehicles (FCHEVs) is the key part to enhance optimal power distribution. Indeed the most recent works are focusing on optimizing hydrogen consumption without taking into consideration the degradation of embedded energy sources. In order to overcome this lack of knowledge this paper describes a new health-conscious EMS algorithm based on Model Predictive Control (MPC) which aims to minimize the battery degradation to extend its lifetime. In this proposed algorithm the health-conscious EMS is normalized in order to address its multi-objective optimization. Then weighting factors are assigned in the objective function to minimize the selected criteria. Compared to most EMSs based on optimization techniques this proposed approach does not require any information about the speed profile which allows it to be used for real-time control of FCHEV. The achieved simulation results show that the proposed approach reduces the economic cost up to 50% for some speed profile keeping the battery pack in a safe range and significantly reducing energy sources degradation. The proposed health-conscious EMS has been validated experimentally and its online operation ability clearly highlighted on a PEMFC delivery postal vehicle.
Aboveground Hydrogen Storage - Assessment of the Potential Market Releveance in a Carbon-Neutral European Energy System
Mar 2024
Publication
Hydrogen storage is expected to play a crucial role in the comprehensive defossilization of energy systems. In this context the focus is typically on underground hydrogen storage (e.g. in salt caverns). However aboveground storage which is independent of geological conditions and might offer other technical advantages could provide systemic benefits and thereby gain shares in the hydrogen storage market. Against this background this paper examines the market relevance of aboveground compared to underground hydrogen storage. Using the opensource energy system model and optimization framework of Europe PyPSA-Eur the influence of geological independence storage cost relations and technical storage characteristics (i.e. efficiencies) on mentioned market relevance of aboveground hydrogen storage are investigated. Further the expectable market relevance based on current cost projections for the future is assessed. The studies show that in terms of hydrogen capacities aboveground hydrogen storage plays a considerably smaller role compared to underground hydrogen storage. Even when assuming comparatively low aboveground storage cost it will not exceed 1.7% (1.9 TWhH2LHV) of total hydrogen storage capacities in a cost-optimal European energy system. Regarding the amounts of annually stored hydrogen aboveground storage could play a larger role reaching a maximum share of 32.5% (168 TWhH2 LHV a-1) of total stored hydrogen throughout Europe. However these shares are only achievable for low cost storage in particularly suited energy system supply configurations. For higher aboveground storage costs or lower efficiencies shares drop below 10% sharply. The analysis identifies some especially influential factors for achieving higher market relevance. Besides storage costs the demand-orientation of a particular aboveground storage system (e.g. hydrogen storage at demand pressure levels) plays an essential role in market relevance. Further overall efficiency can be a beneficial factor. Still current projections of future techno-economic characteristics show that aboveground hydrogen storage is too expensive or too inefficient compared to underground storage. Therefore to achieve notable market relevance rather drastic cost reductions beyond current expectations would be needed for all assessed aboveground hydrogen storage technologies.
Knowledge and Technology Transfer via Publications, Patents, Standards: Exploring the Hydrogen Technological Innovation System
Nov 2022
Publication
Clean technologies play a crucial role in reducing greenhouse gas emissions and protecting the climate. Hydrogen is a promising energy carrier and fuel that can be used in many applications. We explore the global hydrogen technological innovation system (TIS) by analyzing the three knowledge and technology transfer channels of publications patents and standards. Since the adoption of hydrogen technologies requires trust in their safety this study specifically also focuses on hydrogen safety. Our results show that general and hydrogen safety research has increased significantly while patenting experienced stagnation. An analysis of the non-patent literature in safety patents shows little recognition of scientific publications. Similarly publications are under-represented in the analyzed 75 international hydrogen and fuel cell standards. This limited transfer of knowledge from published research to standards points to the necessity for greater involvement of researchers in standardization. We further derive implications for the hydrogen TIS and recommendations for a better and more impactful alignment of the three transfer channels.
Water Electrolysis: From Textbook Knowledge to the Latest Scientific Strategies and Industrial Developments
May 2022
Publication
Replacing fossil fuels with energy sources and carriers that are sustainable environmentally benign and affordable is amongst the most pressing challenges for future socio-economic development. To that goal hydrogen is presumed to be the most promising energy carrier. Electrocatalytic water splitting if driven by green electricity would provide hydrogen with minimal CO2 footprint. The viability of water electrolysis still hinges on the availability of durable earth-abundant electrocatalyst materials and the overall process efficiency. This review spans from the fundamentals of electrocatalytically initiated water splitting to the very latest scientific findings from university and institutional research also covering specifications and special features of the current industrial processes and those processes currently being tested in large-scale applications. Recently developed strategies are described for the optimisation and discovery of active and durable materials for electrodes that ever-increasingly harness first principles calculations and machine learning. In addition a technoeconomic analysis of water electrolysis is included that allows an assessment of the extent to which a large-scale implementation of water splitting can help to combat climate change. This review article is intended to cross-pollinate and strengthen efforts from fundamental understanding to technical implementation and to improve the ‘junctions’ between the field’s physical chemists materials scientists and engineers as well as stimulate much-needed exchange among these groups on challenges encountered in the different domains.
Green Hydrogen in Europe: Do Strategies Meet Expectations?
Dec 2021
Publication
The possibility of producing hydrogen as an energy carrier or raw material through electrolysis of water so-called green hydrogen has been on the table as a technological option for a long time. However low conversion efficiency and a dubious climate balance have stood in the way of large-scale application ever since. Within the last three to four years however this view has changed significantly. In addition to technological improvements the increasing speed of the expansion of volatile renewable energies in Europe has also contributed to this since in principle a nearly climate-neutral utilisation of excess generation is possible through the use of hydrogen as an energy carrier in electrolysis. In addition hydrogen or products derived from it can be used in a variety of ways as a final energy carrier in all energy-intensive activities: industry heating and transport. For this reason green hydrogen production could play a key role in interconnecting all energy consuming sectors (sector coupling) a long-term goal necessary for achieving the decarbonisation of the European economy.
Methane Pyrolysis for CO2-Free H2 Production: A Green Process to Overcome Renewable Energies Unsteadiness
Aug 2020
Publication
The Carbon2Chem project aims to convert exhaust gases from the steel industry into chemicals such as methanol to reduce CO2 emissions. Here H2 is required for the conversion of CO2 into methanol. Although much effort is put to produce H2 from renewables the use of fossil fuels especially natural gas seems to be fundamental in the short term. For this reason the development of clean technologies for the processing of natural gas with a low environmental impact has become a topic of utmost importance. In this context methane pyrolysis has received special attention to produce CO2-free H2.
Protocol for Heavy-duty Hydrogen Refueling: A Modelling Benchmark
Sep 2021
Publication
For the successful deployment of the Heavy Duty (HD) hydrogen vehicles an associated infrastructure in particular hydrogen refueling stations (HRS) should be reliable compliant with regulations and optimized to reduce the related costs. FCH JU project PRHYDE aims to develop a sophisticated protocol dedicated to HD applications. The target of the project is to develop protocol and recommendations for an efficient refueling of 350 500 and 700 bar HD tanks of types III and IV. This protocol is based on modeling results as well as experimental data. Different partners of the PRHYDE European project are closely working together on this target. However modeling approaches and corresponding tools must first be compared and validated to ensure the high level of reliability for the modeling results. The current paper presents the benchmark performed in the frame of the project by Air Liquide Engie Wenger Engineering and NREL. The different models used were compared and calibrated to the configurations proposed by the PRHYDE project. In addition several scenarios were investigated to explore different cases with high ambient temperatures.
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.
Mathematical Modeling of Unstable Transport in Underground Hydrogen Storage
Apr 2015
Publication
Within the framework of energy transition hydrogen has a great potential as a clean energy carrier. The conversion of electricity into hydrogen for storage and transport is an efficient technological solution capable of significantly reducing the problem of energy shortage. Underground hydrogen storage (UHS) is the best solution to store the large amount of excess electrical energy arising from the excessive over-production of electricity with the objective of balancing the irregular and intermittent energy production typical of renewable sources such as windmills or solar. Earlier studies have demonstrated that UHS should be qualitatively identical to the underground storage of natural gas. Much later however it was revealed that UHS is bound to incur peculiar difficulties as the stored hydrogen is likely to be used by the microorganisms present in the rocks for their metabolism which may cause significant losses of hydrogen. This paper demonstrates that besides microbial activities the hydrodynamic behavior of UHS is very unique and different from that of a natural gas storage.
Carbon Footprint and Energy Transformation Analysis of Steel Produced via a Direct Reduction Plant with an Integrated Electric Melting Unit
Aug 2022
Publication
The production of fat steel products is commonly linked to highly integrated sites which include hot metal generation via the blast furnace basic oxygen furnace (BOF) continuous casting and subsequent hot-rolling. In order to reach carbon neutrality a shift away from traditional carbon-based metallurgy is required within the next decades. Direct reduction (DR) plants are capable to support this transition and allow even a stepwise reduction in CO2 emissions. Nevertheless the implementation of these DR plants into integrated metallurgical plants includes various challenges. Besides metallurgy product quality and logistics special attention is given on future energy demand. On the basis of carbon footprint methodology (ISO 14067:2019) diferent scenarios of a stepwise transition are evaluated and values of possible CO2equivalent (CO2eq) reduction are coupled with the demand of hydrogen electricity natural gas and coal. While the traditional blast furnace—BOF route delivers a surplus of electricity in the range of 0.7 MJ/kg hot-rolled coil; this surplus turns into a defcit of about 17 MJ/ kg hot-rolled coil for a hydrogen-based direct reduction with an integrated electric melting unit. On the other hand while the product carbon footprint of the blast furnace-related production route is 2.1 kg CO2eq/kg hot-rolled coil; this footprint can be reduced to 0.76 kg CO2eq/kg hot-rolled coil for the hydrogen-related route provided that the electricity input is from renewable energies. Thereby the direct impact of the processes of the integrated site can even be reduced to 0.15 kg CO2eq/ kg hot-rolled coil. Yet if the electricity input has a carbon footprint of the current German or European electricity grid mix the respective carbon footprint of hot-rolled coil even increases up to 3.0 kg CO2eq/kg hot-rolled coil. This underlines the importance of the availability of renewable energies.
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.
System Analysis and Requirements Derivation of a Hydrogen-electric Aircraft Powertrain
Sep 2022
Publication
In contrast to sustainable aviation fuels for use in conventional combustion engines hydrogen-electric powertrains constitute a fundamentally novel approach that requires extensive effort from various engineering disciplines. A transient system analysis has been applied to a 500 kW shaft-power-class powertrain. The model was fed with high-level system requirements to gain a fundamental understanding of the interaction between sub-systems and components. Transient effects such as delays in pressure build up heat transfer and valve operation substantially impact the safe and continuous operation of the propulsion system throughout a typical mission profile which is based on the Daher TBM850. The lumped-parameters network solver provides results quickly which are used to derive requirements for subsystems and components which support their in-depth future development. E.g. heat exchanger transfer rates and pressure drop of the motor's novel hydrogen cooling system are established. Furthermore improvements to the system architecture such as a compartmentalization of the tank are identified.
Derivation and Validation of a Reference Data-based Real Gas Model for Hydrogen
Mar 2023
Publication
Hydrogen plays an important role for the decarbonization of the energy sector. In its gaseous form it is stored at pressures of up to 1000 bar at which real gas effects become relevant. To capture these effects in numerical simulations accurate real gas models are required. In this work new correlation equations for relevant hydrogen properties are developed based on the Reference Fluid Thermodynamic and Transport Properties Database (REFPROP). Within the regarded temperature (150e400 K) and pressure (0.1e1000 bar) range this approach yields a substantially improved accuracy compared to other databased correlations. Furthermore the developed equations are validated in a numerical simulation of a critical flow Venturi nozzle. The results are in much better accordance with experimental data compared to a cubic equation of state model. In addition the simulation is even slightly faster.
Implementation of Fuel Cells in Aviation from a Maintenance, Repair and Overhaul Perspective
Dec 2022
Publication
Hydrogen is one of the most promising power sources for meeting the aviation sector’s long-term decarbonization goals. Although on-board hydrogen systems namely fuel cells are extensively researched the maintenance repair and overhaul (MRO) perspective remains mostly unaddressed. This paper analyzes fuel cells from an MRO standpoint based on a literature review and comparison with the automotive sector. It also examines how well the business models and key resources of MRO providers are currently suited to provide future MRO services. It is shown that fuel cells require extensive MRO activities and that these are needed to meet the aviation sector’s requirements for price safety and especially durability. To some extent experience from the automotive sector can be built upon particularly with respect to facility requirements and qualification of personnel. Yet MRO providers’ existing resources only partially allow them to provide these services. MRO providers’ underlying business models must adapt to the implementation of fuel cells in the aviation sector. MRO providers and services should therefore be considered and act as enablers for the introduction of fuel cells in the aviation industry.
Solar Hydrogen Fuel Generation from Wastewater—Beyond Photoelectrochemical Water Splitting: A Perspective
Oct 2022
Publication
Green hydrogen—a carbon-free renewable fuel—has the capability to decarbonise a variety of sectors. The generation of green hydrogen is currently restricted to water electrolysers. The use of freshwater resources and critical raw materials however limits their use. Alternative water splitting methods for green hydrogen generation via photocatalysis and photoelectrocatalysis (PEC) have been explored in the past few decades; however their commercial potential still remains unexploited due to the high hydrogen generation costs. Novel PEC-based simultaneous generation of green hydrogen and wastewater treatment/high-value product production is therefore seen as an alternative to conventional water splitting. Interestingly the organic/inorganic pollutants in wastewater and biomass favourably act as electron donors and facilitate the dual-functional process of recovering green hydrogen while oxidising the organic matter. The generation of green hydrogen through the dual-functional PEC process opens up opportunities for a “circular economy”. It further enables the end-of-life commodities to be reused recycled and resourced for a better life-cycle design while being economically viable for commercialisation. This review brings together and critically analyses the recent trends towards simultaneous wastewater treatment/biomass reforming while generating hydrogen gas by employing the PEC technology. We have briefly discussed the technical challenges associated with the tandem PEC process new avenues techno-economic feasibility and future directions towards achieving net neutrality.
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