Germany

In this study Distribution of Relaxation Times (DRT) was successfully demonstrated in the analysis of the impedance spectra of High-Temperature Polymer Electrolyte Membrane Fuel Cells (HT-PEMFC) doped with phosphoric acid. Electrochemical impedance spectroscopy (EIS) was performed and the quality of the recorded spectra was verified by Kramers-Kronig relations. DRT was then applied to the measured spectra and polarization losses were separated on the basis of their typical time constants. The main features of the distribution function were assigned to the cell’s polarization processes by selecting appropriate experimental conditions. DRT can be used to identify individual internal HT-PEMFC fuel cell phenomena without any a-priori knowledge about the physics of the system. This method has the potential to further improve EIS spectra interpretation with either equivalent circuits or physical models.

This research aims to determine the position and the breakthrough trajectory of sustainable energy technologies. Fine-grained insights into these breakthrough positions and trajectories are limited. This research seeks to fill this gap by analyzing sustainable energy technologies’ breakthrough positions and trajectories in terms of development application and upscaling. To this end the breakthrough positions and trajectories of seven sustainable energy technologies i.e. hydrogen from seawater electrolysis hydrogen airplanes inland floating photovoltaics redox flow batteries hydrogen energy for grid balancing hydrogen fuel cell electric vehicles and smart sustainable energy houses are analyzed. This is guided by an extensively researched and literature-based model that visualizes and describes these technologies’ experimentation and demonstration stages. This research identifies where these technologies are located in their breakthrough trajectory in terms of the development phase (prototyping production process and organization and niche market creation and sales) experiment and demonstration stage (technical organizational and market) the form of collaboration (public–private private–public and private) physical location (university and company laboratories production sites and marketplaces) and scale-up type (demonstrative and first-order and second-order transformative). For scientists this research offers the opportunity to further refine the features of sustainable energy technologies’ developmental positions and trajectories at a detailed level. For practitioners it provides insights that help to determine investments in various sustainable energy technologies.

This study offers a comprehensive analysis of the feasibility of green hydrogen economies in Western and Southern African regions focusing on the ECOWAS and SADC countries. Utilizing a novel approach based on composite indicators the research evaluates the potential readiness and overall feasibility of green hydrogen production and export across these regions. The study incorporates various factors including the technical potential of renewable energy sources water resource availability energy security and existing infrastructure for transport and export. Country-specific analyses reveal unique insights into the diverse potential of nations like South Africa Lesotho Ghana Nigeria Angola and Namibia each with its unique strengths and challenges in the context of green hydrogen. The research findings underscore the complexity of developing green hydrogen economies highlighting the need for nuanced region-specific approaches that consider technical socioeconomic geopolitical and environmental factors. The paper concludes that cooperation and integration between countries in the regions may be crucial for the success of a future green hydrogen economy

Climate change is projected to have substantial economic social and environmental impacts worldwide. Currently the leading solutions for hydrogen storage are in salt caverns and depleted natural gas reservoirs. However the required geological formations are limited to certain regions. To increase alternatives for hydrogen storage this paper proposes storing hydrogen in pipes filled with gravel in lakes hydropower and pumped hydro storage reservoirs. Hydrogen is insoluble in water non-toxic and does not threaten aquatic life. Results show the levelized cost of hydrogen storage to be 0.17 USD kg−1 at 200 m depth which is competitive with other large scale hydrogen storage options. Storing hydrogen in lakes hydropower and pumped hydro storage reservoirs increases the alternatives for storing hydrogen and might support the development of a hydrogen economy in the future. The global potential for hydrogen storage in reservoirs and lakes is 3 and 12 PWh respectively. Hydrogen storage in lakes and reservoirs can support the development of a hydrogen economy in the future by providing abundant and cheap hydrogen storage.

By passing the delegated acts supplementing the revised Renewable Energy Directive the European Commission has recently set a regulatory benchmark for the classifcation of green hydrogen in the European Union. Controversial reactions to the restricted power purchase for electrolyser operation refect the need for more clarity about the efects of the delegated acts on the cost and the renewable characteristics of green hydrogen. To resolve this controversy we compare diferent power purchase scenarios considering major uncertainty factors such as electricity prices and the availability of renewables in various European locations. We show that the permission for unrestricted electricity mix usage does not necessarily lead to an emission intensity increase partially debilitating concerns by the European Commission and could notably decrease green hydrogen production cost. Furthermore our results indicate that the transitional regulations adopted to support a green hydrogen production ramp-up can result in similar cost reductions and ensure high renewable electricity usage.

Green hydrogen will play a crucial role in the future of emission reduction in air traffic in the long-term as it will completely eliminate CO2 emissions and significantly reduce other pollutants such as contrails and nitrogen oxides. Hydrogen offers a promising alternative to kerosene for short- and medium-haul flights particularly through direct combustion and hydrogen fuel cell technology in new aircraft concepts. Against the background of the immense capital-intensive infrastructure adjustments that are required at airports for this purpose and the simultaneously high future hydrogen demand for the shipping industry this paper analyses the emission savings potential in Europe if airports near seaports would switch to hydrogen-powered flight connections.

The decarbonization of industrial process heat is one of the bigger challenges of the global energy transition. Process heating accounts for about 20% of final energy demand in Germany and the situation is similar in other industrialized nations around the globe. Process heating is indispensable in the manufacturing processes of products and materials encountered every day ranging from food beverages paper and textiles to metals ceramics glass and cement. At the same time process heating is also responsible for significant greenhouse gas emissions as it is heavily dependent on fossil fuels such as natural gas and coal. Thus process heating needs to be decarbonized. This review article explores the challenges of decarbonizing industrial process heat and then discusses two of the most promising options the use of electric heating technologies and the substitution of fossil fuels with low-carbon hydrogen in more detail. Both energy carriers have their specific benefits and drawbacks that have to be considered in the context of industrial decarbonization but also in terms of necessary energy infrastructures. The focus is on high-temperature process heat (>400 ◦C) in energy-intensive basic materials industries with examples from the metal and glass industries. Given the heterogeneity of industrial process heating both electricity and hydrogen will likely be the most prominent energy carriers for decarbonized high-temperature process heat each with their respective advantages and disadvantages.

Underground hydrogen storage in porous rocks is a promising method to stabilize renewable energy fluctuations. However data on the geochemical reactivity of hydrogen with reservoir rocks and its potential effects on reservoir performance are limited. This study investigates the geochemical reactivity of hydrogen with Bunt sandstein reservoir sandstones from northern Germany collected at a depth of about 2.5 km. Experiments were performed at 100 ◦C and 150 bar hydrogen partial pressure for four weeks examining scenarios with dry hydrogen synthetic saline fluid with hydrogen synthetic saline fluid with helium (as a control) and an oxidation environment (air). We measured permeability porosity magnetic susceptibility and fluid element concentration before and after the experiments. Results showed no significant mineral changes attributed to hydrogen. Mag netic susceptibility indicated no formation of magnetic minerals such as magnetite and pyrrhotite. Minor var iations in permeability and porosity were attributed to anhydrite dissolution from fluid chemistry nonequilibrium. Overall our findings suggest hydrogen interactions with Buntsandstein sandstone (no pyrite content) at temperatures up to 100 ◦C do not risk hydrogen loss or reservoir performance degradation.

The defossilization of industry has far-reaching implications regarding the future demand for hydrogen and other forms of energy. This paper presents and applies a fundamental bottom-up model that relies on techno-economic data of industrial production processes. Its aim is to identify across a range of scenarios the most cost-effective low-carbon options considering a variety of production systems. Subsequently it derives the hydrogen and electricity demand that would result from the implementation of these least-cost low-carbon options in process industries in Germany. Aligning with the German government's target year for achieving climate neutrality this study’s reference year is 2045. The primary contribution lies in analyzing which hydrogen-based and direct electrification solutions would be cost-effective for a range of energy price levels under climate-neutral industrial production and what the resulting hydrogen and electricity demand would be. To this end the methodology of this paper comprises the following steps: selection of the relevant industries (I) definition of conventional reference production systems and their low-carbon options (II) investigation and processing of the techno-economic data of the standardized production systems (III) establishment of a scenario framework (IV) determination of the least-cost low-carbon solution of a conventional reference production system under the scenario assumptions made (V) and estimation of the resulting hydrogen and electricity demand (VI). According to the results the expected industrial hydrogen consumption in 2045 ranges from 255 TWh for higher hydrogen prices in or above the range of onshore wind-based green hydrogen supply costs to up to 542 TWh for very low hydrogen prices corresponding to typical blue hydrogen production costs. Meanwhile the direct electricity consumption of the process industries in the results ranges from 122 TWh for these rather low hydrogen prices to 368 TWh for the higher hydrogen prices in the region of or above the hydrogen supply costs from the electrolysis of energy from an onshore wind farm. Most of the break-even hydrogen prices that are relevant to the choice of low-carbon options are in the range of the benchmark purchase costs for blue hydrogen and green hydrogen produced from offshore wind power which span between €40 per MWh and €97 per MWh.

The green-hydrogen sector has created considerable expectations in the Global South about export-oriented development and industrial path creation. However whether and how these expectations are really materializing requires further scrutiny. This article develops a conceptual approach that we call governance of futuremaking. Thereby we want to understand how actors try to coordinate their expectations about future economic development in different contexts and across scales over time. We conceptualize the emergence of new regional development trajectories as resulting from the use of governance instruments with an increasing bindingness which reflect the interplay between governance of and by expectations. Based on this approach we analyze and compare green-hydrogen activities in Namibia and South Africa. We find that future-making is becoming more binding in both countries but has not resulted in path creation yet.