Germany

In which way and in which sectors will renewable energy be integrated in the German Energy System by 2030 2040 and 2050? How can the resulting energy system be characterised following a −95% greenhouse gas emission reduction scenario? Which role will hydrogen play? To address these research questions techno-economic energy system modelling was performed. Evaluation of the resulting operation of energy technologies was carried out from a system and a business point of view. Special consideration of gas technologies such as hydrogen production transport and storage was taken as a large-scale and long-term energy storage option and key enabler for the decarbonisation of the non-electric sectors. The broad set of results gives insight into the entangled interactions of the future energy technology portfolio and its operation within a coupled energy system. Amongst other energy demands CO2 emissions hydrogen production and future power plant capacities are presented. One main conclusion is that integrating the first elements of a large-scale hydrogen infrastructure into the German energy system already by 2030 is necessary for ensuring the supply of upscaling demands across all sectors. Within the regulatory regime of 2020 it seems that this decision may come too late which jeopardises the achievement of transition targets within the horizon 2050.

Underground hydrogen storage is a potential way to balance seasonal fluctuations in energy production from renewable energies. The risks of hydrogen storage in depleted gas fields include the conversion of hydrogen to CH4(g) and H2S(g) due to microbial activity gas–water–rock interactions in the reservoir and cap rock which are connected with porosity changes and the loss of aqueous hydrogen by diffusion through the cap rock brine. These risks lead to loss of hydrogen and thus to a loss of energy. A hydrogeochemical modeling approach is developed to analyze these risks and to understand the basic hydrogeochemical mechanisms of hydrogen storage over storage times at the reservoir scale. The one-dimensional diffusive mass transport model is based on equilibrium reactions for gas–water–rock interactions and kinetic reactions for sulfate reduction and methanogenesis. The modeling code is PHREEQC (pH-REdox-EQuilibrium written in the C programming language). The parameters that influence the hydrogen loss are identified. Crucial parameters are the amount of available electron acceptors the storage time and the kinetic rate constants. Hydrogen storage causes a slight decrease in porosity of the reservoir rock. Loss of aqueous hydrogen by diffusion is minimal. A wide range of conditions for optimized hydrogen storage in depleted gas fields is identified.

Electrocatalytic water splitting is the key process for the formation of green fuels for energy transport and storage in a sustainable energy economy. Besides electricity it requires water an aspect that seldomly has been considered until recently. As freshwater is a limited resource (<1% of earth's water) lately plentiful reports were published on direct seawater (around 96.5% of earth's water) splitting without or with additives (buffers or bases). Alternatively the seawater can be split in two steps where it is first purified by reverse osmosis and then split in a conventional water electrolyser. This quantitative analysis discusses the challenges of the direct usage of non-purified seawater. Further herein we compare the energy requirements and costs of seawater purification with those of conventional water splitting. We find that direct seawater splitting has substantial drawbacks compared to conventional water splitting and bears almost no advantage. In short it is less promising than the two-step scenario as the capital and operating costs of water purification are insignificant compared to those of electrolysis of pure water.

With Japan’s current plans to reach a fully decarbonized society by 2050 and establish a hydrogen society substantial changes to its energy system need to be made. Due to the limited land availability in Japan significant amounts of hydrogen are planned to be imported to reach both targets. In this paper a novel stochastic version of the open-source multi-sectoral Global Energy System Model in conjunction with a power system dispatch model is used to analyze the impacts of both availability and price of hydrogen imports on the transformation of the Japanese energy system considering a net-zero emission target. This analysis highlights that hydrogen poses a valuable resource in specific sectors of the energy system. Therefore importing hydrogen can indeed positively impact energy system developments although up to 19mt of hydrogen will be imported in the case with the cheapest available hydrogen. In contrast without any hydrogen imports power demand nearly doubles in 2050 compared to 2019 due to extensive electrification in non-electricity sectors. However hydrogen imports are not necessarily required to reach net-zero emissions. In all cases however large-scale investments into renewable energy sources need to be made.

Achieving the goals of the Paris Agreement requires increased global climate action especially towards the production and use of synthetic e-fuels. This paper focuses on aviation and maritime transport and the role of green hydrogen for indirect electrification of industry sectors. Based on a sound analysis of existing multilateral cooperation the paper proposes four potential initiatives to increase climate ambition of the G20 countries in the respective policy field: a Sustainable e-Kerosene Alliance a Sustainable e-fuel Alliance for Maritime Shipping a Hard-to-Abate Sector Partnership and a Global Supply-demand-partnership.

The full report can be found here on the Umweltbundesamt website

The Life Cycle Sustainability Assessment (LCSA) is a proven method for sustainability assessment. However the interpretation phase of an LCSA is challenging because many different single results are obtained. Additionally performing a Multi-Criteria Decision Analysis (MCDA) is one way—not only for LCSA—to gain clarity about how to interpret the results. One common form of MCDAs are outranking methods. For these type of methods it becomes of utmost importance to clarify when results become preferable. Thus thresholds are commonly used to prevent decisions based on results that are actually indifferent between the analyzed options. In this paper a new approach is presented to identify and quantify such thresholds for Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) based on uncertainty of Life Cycle Impact Assessment (LCIA) methods. Common thresholds and this new approach are discussed using a case study on finding a preferred location for sustainable industrial hydrogen production comparing three locations in European countries. The single LCSA results indicated different preferences for the environmental economic and social assessment. The application of PROMETHEE helped to find a clear solution. The comparison of the newly-specified thresholds based on LCIA uncertainty with default thresholds provided important insights of how to interpret the LCSA results regarding industrial hydrogen production.

In the future hydrogen (H2) will play a significant role in the sustainable supply of energy and raw materials to various sectors. Therefore the electrolysis of water required for industrial‐ scale H2 production represents a key component in the generation of renewable electricity. Within the scope of fundamental research work on cell components for polymer electrolyte membrane (PEM) electrolyzers and application‐oriented living labs an MW electrolysis system was used to further improve industrial‐scale electrolysis technology in terms of its basic structure and systems‐ related integration. The planning of this work as well as the analytical and technical approaches taken along with the essential results of research and development are presented herein. The focus of this study is the test facility for a megawatt PEM electrolysis stack with the presentation of the design processing and assembly of the main components of the facility and stack.

Green hydrogen produced by power‐to‐gas will play a major role in the defossilization of the energy system as it offers both carbon‐neutral chemical energy and the chance to provide flexibility. This paper provides an extensive analysis of hydrogen production in decentralized energy systems as well as possible operation modes (H2 generation or system flexibility). Modelling was realized for municipalities—the lowest administrative unit in Germany thus providing high spatial resolution—in the linear optimization framework OEMOF. The results allowed for a detailed regional analysis of the specific operating modes and were analyzed using full‐load hours share of used negative residual load installed capacity and levelized cost of hydrogen to derive the operation mode of power‐to‐gas to produce hydrogen. The results show that power‐to‐gas is mainly characterized by constant hydrogen production and rarely provides flexibility to the system. Main drivers of this dominant operation mode include future demand for hydrogen and the fact that high full‐load hours reduce hydrogen‐production costs. However changes in the regulatory market and technical framework could promote more flexibility and support possible use cases for the central technology to succeed in the energy transition.

Hydrogen produced in a polymer electrolyte membrane (PEM) electrolyzer must be stored under high pressure. It is discussed whether the gas should be compressed in subsequent gas compressors or by the electrolyzer. While gas compressor stages can be reduced in the case of electrochemical compression safety problems arise for thin membranes due to the undesired permeation of hydrogen across the membrane to the oxygen side forming an explosive gas. In this study a PEM system is modeled to evaluate the membrane-specific total system efficiency. The optimum efficiency is given depending on the external heat requirement permeation cell pressure current density and membrane thickness. It shows that the heat requirement and hydrogen permeation dominate the maximum efficiency below 1.6 V while above the cell polarization is decisive. In addition a pressure-optimized cell operation is introduced by which the optimum cathode pressure is set as a function of current density and membrane thickness. This approach indicates that thin membranes do not provide increased safety issues compared to thick membranes. However operating an N212-based system instead of an N117-based one can generate twice the amount of hydrogen at the same system efficiency while only one compressor stage must be added.

Achieving climate-neutrality requires considerable investment in energy storage systems (ESS) to integrate variable renewable energy sources into the grid. However investments into ESS are often unprofitable in particular for grid-scale battery storage and green hydrogen technologies prompting many actors to call for policy intervention. This study investigates investor-specific risk-return preferences for ESS investment and derives policy recommendations. Insights are drawn from 1605 experimental investment-related decisions obtained from 42 high-level institutional investors and utility representatives. Results reveal that both investor groups view revenue stacking as key to making ESS investment viable. While the expected return on investment is the most important project characteristic risk-return preferences for other features diverge between groups. Institutional investors appear more open to exploring new technological ventures (20% of utility respondents would not consider making investments into solar photovoltaic-hydrogen) whereas utilities seem to prefer greenfield projects (23% of surveyed institutional investors rejected such projects). Interestingly both groups show strong aversion towards energy market price risk. Institutional investors require a premium of 6.87 percentage points and utilities 5.54 percentage points for moving from a position of fully hedged against market price risk to a scenario where only 20% of revenue is fixed underlining the need for policy support.

The industrial sector is the world’s second largest emitter of greenhouse gases hence a methodology for decarbonizing factory systems is crucial for achieving global climate goals. Hydrogen is an important medium for the transition towards carbon neutral factories due to its broad applicability within the factory including its use in electricity and heat generation and as a process gas or fuel. One of the main challenges is the identification of economically and environmentally suitable design scenarios such as for the entire value chain for hydrogen generation and application. For example the infrastructure for renewable electricity hydrogen generation hydrogen conversion (e.g. into synthetic fuels) storage and transport systems as well as application in the factory. Due to the high volatility of energy generation and the related dynamic interdependencies within a factory system a valid technical economic and environmental evaluation of benefits induced by hydrogen technologies can only be achieved using digital factory models. In this paper we present a framework to integrate hydrogen technologies into factory systems. This enables decision makers to identify promising measures according to their expected impact and collect data for appropriate factory modelling. Furthermore a concept for factory modelling and simulation is presented and demonstrated in a case study from the electronics industry assessing the use of hydrogen for decentralized power and heat generation.

Hydrogen mobility is one option for reducing local emissions avoiding greenhouse gas (GHG) emissions and moving away from a mainly oil-based transport system towards a diversification of energy sources. As hydrogen production can be based on a broad variety of technologies already existing or under development a comprehensive assessment of the different supply chains is necessary regarding not only costs but also diverse environmental impacts. Therefore in this paper a broad variety of hydrogen production technologies using different energy sources renewable and fossil are exemplarily assessed with the help of a Life Cycle Assessment and a cost assessment for Germany. As environmental impacts along with the impact category Climate change five more advanced impact categories are assessed. The results show that from an environmental point of view PEM and alkaline electrolysis are characterized by the lowest results in five out of six impact categories. Supply chains using fossil fuels in contrast have the lowest supply costs; this is true e.g. for steam methane reforming. Solar powered hydrogen production shows low impacts during hydrogen production but high impacts for transport and distribution to Germany. There is no single supply chain that is the most promising for every aspect assessed here. Either costs have to be lowered further or supply chains with selected environmental impacts have to be modified.

Power-to-X processes where renewable energy is converted into storable liquids or gases are considered to be one of the key approaches for decarbonizing energy systems and compensating for the volatility involved in generating electricity from renewable sources. In this context the production of “green” hydrogen and hydrogen-based derivatives is being discussed and tested as a possible solution for the energy-intensive industry sector in particular. Given the sharp ongoing increases in electricity and gas prices and the need for sustainable energy supplies in production systems non-energy-intensive companies should also be taken into account when considering possible utilization paths for hydrogen. This work focuses on the following three utilization paths: “hydrogen as an energy storage system that can be reconverted into electricity” “hydrogen mobility” for company vehicles and “direct hydrogen use”. These three paths are developed modeled simulated and subsequently evaluated in terms of economic and environmental viability. Different photovoltaic system configurations are set up for the tests with nominal power ratings ranging from 300 kWp to 1000 kWp. Each system is assigned an electrolyzer with a power output ranging between 200 kW and 700 kW and a fuel cell with a power output ranging between 5 kW and 75 kW. There are also additional variations in relation to the battery storage systems within these basic configurations. Furthermore a reference variant without battery storage and hydrogen technologies is simulated for each photovoltaic system size. This means that there are ultimately 16 variants to be simulated for each utilization path. The results show that these utilization paths already constitute a reasonable alternative to fossil fuels in terms of costs in variants with a suitable energy system design. For the “hydrogen as an energy storage system” path electricity production costs of between 43 and 79 ct/kWh can be achieved with the 750 kWp photovoltaic system. The “hydrogen mobility” is associated with costs of 12 to 15 ct/km while the “direct hydrogen use” path resulted in costs of 8.2 €/kg. Environmental benefits are achieved in all three paths by replacing the German electricity mix with renewable energy sources produced on site or by substituting hydrogen for fossil fuels. The results confirm that using hydrogen as a storage medium in manufacturing companies could be economically and environmentally viable. These results also form the basis for further studies e.g. on detailed operating strategies for hydrogen technologies in scenarios involving a combination of multiple utilization paths. The work also presents the simulation-based method developed in this project which can be transferred to comparable applications in further studies.

The anticipated upscaling of hydrogen energy applications will involve the storage and transport of hydrogen at cryogenic conditions. Understanding the potential hazard arising from leaks in high-pressure cryogenic storage is needed to improve hydrogen safety. The manuscript reports a series of numerical simulations with detailed chemistry for the transient evolution of ignited high-pressure cryogenic hydrogen jets. The study aims to gain insight of the ignition processes flame structures and dynamics associated with the transient flame evolution. Numerical simulations were firstly conducted for an unignited jet released under the same cryogenic temperature of 80 K and pressure of 200 bar as the considered ignited jets. The predicted hydrogen concentrations were found to be in good agreement with the experimental measurements. The results informed the subsequent simulations of the ignited jets involving four different ignition locations. The predicted time series snapshots of temperature hydrogen mass fraction and the flame index are analyzed to study the transient evolution and structure of the flame. The results show that a diffusion combustion layer is developed along the outer boundary of the jet and a side diffusion flame is formed for the near-field ignition. For the far-field ignition an envelope flame is observed. The flame structure contains a diffusion flame on the outer edge and a premixed flame inside the jet. Due to the complex interactions between turbulence fuel-air mixing at cryogenic temperature and chemical reactions localized spontaneous ignition and transient flame extinguishment are observed. The predictions also captured the experimentally observed deflagration waves in the far-field ignited jets.

Hydrogen dispersion in stagnant environment resulting from blowdown of a vessel storing the gas at cryogenic temperature is simulated using different CFD codes and modelling strategies. The simulations are based on the DISCHA experiments that were carried out by Karlsruhe Institute of Technology (KIT) and Pro-Science (PS). The selected test for the current study involves hydrogen release from a 2.815 dm3 volume tank with an initial pressure of 200 barg and temperature 80 K. During the release the hydrogen pressure in the tank gradually decreased. A total of about 139 gr hydrogen is released through a 4 mm diameter. The temperature time series and the temperature decay rate of the minimum value predicted by the different codes are compared with each other and with the experimentally measured ones. Recommendations for future experimental setup and for modeling approaches for similar releases are provided based on the present analysis. The work is carried out within the EU-funded project PRESLHY.

With the rising threat of climate change green hydrogen is increasingly seen as the high-capacity energy storage and transport medium of the future. This creates an opportunity for low- and middle-income countries to leverage their high renewable energy potential to produce use and export low-cost green hydrogen creating environmental and economic development benefits. While identifying ideal locations for green hydrogen production is critical for countries when defining their green hydrogen strategies there has been a paucity of adequate geospatial planning approaches suitable to low- and middle-income countries. It is essential for these countries to identify green hydrogen production sites which match demand to expected use cases such that their strategies are economically sustainable. This paper therefore develops a novel geospatial cost modelling method to optimize the location of green hydrogen production across different use cases with a focus on suitability to low- and middle-income countries. This method is applied in Kenya to investigate the potential hydrogen supply chain for three use cases: ammonia-based fertilizer freight transport and export. We find hydrogen production costs of e3.7–9.9/kgH2 are currently achievable across Kenya depending on the production location chosen. The cheapest production locations are identified to the south and south-east of Lake Turkana. We show that ammonia produced in Kenya can be cost-competitive given the current energy crisis and that Kenya could export hydrogen to Rotterdam with costs of e7/kgH2 undercutting current market prices regardless of the carrier medium. With expected techno-economic improvements hydrogen production costs across Kenya could drop to e1.8–3.0/kgH2 by 2030.

Hydrogen safety is an important topic for hydrogen energy application. Unintended hydrogen releases and combustions are potential accident scenarios which are of great interest for developing and updating the safety codes and standards. In this paper hydrogen releases and delayed ignitions were studied.

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.

The valorization of integrated steelworks process off-gases as feedstock for synthesizing methane and methanol is in line with European Green Deal challenges. However this target can be generally achieved only through process off-gases enrichment with hydrogen and use of cutting-edge syntheses reactors coupled to advanced control systems. These aspects are addressed in the RFCS project i3 upgrade and the central role of hydrogen was evident from the first stages of the project. First stationary scenario analyses showed that the required hydrogen amount is significant and existing renewable hydrogen production technologies are not ready to satisfy the demand in an economic perspective. The poor availability of low-cost green hydrogen as one of the main barriers for producing methane and methanol from process off-gases is further highlighted in the application of an ad-hoc developed dispatch controller for managing hydrogen intensified syntheses in integrated steelworks. The dispatch controller considers both economic and environmental impacts in the cost function and although significant environmental benefits are obtainable by exploiting process off-gases in the syntheses the current hydrogen costs highly affect the dispatch controller decisions. This underlines the need for big scale green hydrogen production processes and dedicated green markets for hydrogen-intensive industries which would ensure easy access to this fundamental gas paving the way for a C-lean and more sustainable steel production.

Environmental emissions global warming and energy-related concerns have accelerated the advancements in conventional vehicles that primarily use internal combustion engines. Among the existing technologies hydrogen fuel cell electric vehicles and fuel cell hybrid electric vehicles may have minimal contributions to greenhouse gas emissions and thus are the prime choices for environmental concerns. However energy management in fuel cell electric vehicles and fuel cell hybrid electric vehicles is a major challenge. Appropriate control strategies should be used for effective energy management in these vehicles. On the other hand there has been significant progress in artificial intelligence machine learning and designing data-driven intelligent controllers. These techniques have found much attention within the community and state-of-the-art energy management technologies have been developed based on them. This manuscript reviews the application of machine learning and intelligent controllers for prediction control energy management and vehicle to everything (V2X) in hydrogen fuel cell vehicles. The effectiveness of data-driven control and optimization systems are investigated to evolve classify and compare and future trends and directions for sustainability are discussed.

The use of fossil fuels has caused many environmental issues including greenhouse gas emissions and associated climate change. Several studies have focused on mitigating this problem. One dynamic direction for emerging sources of future renewable energy is the use of hydrogen energy. In this research we evaluate the sourcing decision for a hydrogen supply chain in the context of a case study in Thailand using group decision making analysis for policy implications. We use an integrative multi-criteria decision analysis (MCDA) tool which includes an analytic hierarchy process (AHP) fuzzy AHP (FAHP) and data envelopment analysis (DEA) to analyze weighted criteria and sourcing alternatives using data collected from a group of selected experts. A list of criteria related to sustainability paradigms and sourcing decisions for possible use of hydrogen energy including natural gas coal biomass and water are evaluated. Our results reveal that political acceptance is considered the most important criterion with a global weight of 0.514 in the context of Thailand. Additionally natural gas is found to be the foreseeable source for hydrogen production in Thailand with a global weight of 0.313. We also note that the analysis is based on specific data inputs and that an alternative with a lower score does not imply that the source is not worth exploring.

Germany the European Union member state with the largest fiscal space and its leading manufacturer of industrial goods is pursuing an ambitious hydrogen strategy aiming at establishing itself as a major technology provider and importer of green hydrogen. The success of its hydrogen strategy represents not only a key element in realizing the European vision of climate neutrality but also a central driver of an emerging global hydrogen economy. This article provides a detailed review of German policy highlighting its prominent international dimension and its implications for the development of a global renewable hydrogen economy. It provides an overview of the strategy’s central goals and how these have evolved since the launch of the strategy in 2020. Next it moves on to provide an overview of the strategy’s main areas of intervention and highlights corresponding policy instruments. For this we draw on a comprehensive assessment of hydrogen policy instruments which have been systematically analyzed and coded. This was complemented by a detailed analysis of policy documents and information gathered in six interviews with government officials and staff of key implementing agencies. The article places particular emphasis on the strategy’s international dimension. While less significant in financial terms than domestic hydrogen-related spending it represents a defining feature of the German hydrogen strategy setting it apart from strategies in other major economies. The article closes with a reflection on the key features of the strategy compared to other important countries identifies gaps of the strategy and discusses important avenues for future research.

Biomass gasification is a versatile thermochemical process that can be used for direct energy applications and the production of advanced liquid and gaseous energy carriers. In the present work the results are presented concerning the H2 production at a high purity grade from biomass feedstocks via steam/oxygen gasification. The data demonstrating such a process chain were collected at an innovative gasification prototype plant coupled to a portable purification system (PPS). The overall integration was designed for gas conditioning and purification to hydrogen. By using almond shells as the biomass feedstock from a product gas with an average and stable composition of 40%-v H2 21%-v CO 35%-v CO2 2.5%-v CH4 the PPS unit provided a hydrogen stream with a final concentration of 99.99%-v and a gas yield of 66.4%.

The goals of the long-term tests were to see the impact of blends of hydrogen and natural gas on the technical condition of the appliances and their performance after several hours of operation. To do so they were run through an accelerated test program amounting to more than 3000 testing hours for the boilers and more than 2500 testing hours for the cookers. The percentage of hydrogen in the test gas was 30% by volume. Three boilers and two cookers were tested by DGC and two boilers by GWI. This report describes the test protocol the results and analysis on the seven appliances tested.

This paper analyses some possible means by which renewable power could be integrated into the steel manufacturing process with techniques such as blast furnace gas recirculation (BF-GR) furnaces that utilize carbon capture a higher share of electrical arc furnaces (EAFs) and the use of direct reduced iron with hydrogen as reduction agent (H-DR). It is demonstrated that these processes could lead to less dependence on—and ultimately complete independence from—coal. This opens the possibility of providing the steel industry with power and heat by coupling to renewable power generation (sector coupling). In this context it is shown using the example of Germany that with these technologies reductions of 47–95% of CO2 emissions against 1990 levels and 27–95% of primary energy demand against 2008 can be achieved through the integration of 12–274 TWh of renewable electrical power into the steel industry. Thereby a substantial contribution to reducing CO2 emissions and fuel demand could be made (although it would fall short of realizing the German government’s target of a 50% reduction in power consumption by 2050).