Germany

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.

Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och-Function [1] was fitted on the measured cyclic lifetimes.<br/><br/>The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increased by approximately 60 %. Both S-N curves show a distinct S-shape but also significant differences. Under LH2 environment the transition from LCF- to HCF-region as well as the transition to the fatigue limit is shifted to higher cyclic lifetimes compared to ambient test results. The investigation of the crack surfaces showed distinct differences between ambient and LH2 conditions. These observed differences are important factors in the fatigue behavior change.

Proton exchange membrane water electrolysis (PEMWE) is a key technology for future sustainable energy systems. Proton exchange membrane (PEM) electrolysis cells use iridium one of the scarcest elements on earth as catalyst for the oxygen evolution reaction. In the present study the expected iridium demand and potential bottlenecks in the realization of PEMWE for hydrogen production in the targeted GW a−1 scale are assessed in a model built on three pillars: (i) an in-depth analysis of iridium reserves and mine production (ii) technical prospects for the optimization of PEM water electrolyzers and (iii) PEMWE installation rates for a market ramp-up and maturation model covering 50 years. As a main result two necessary preconditions have been identified to meet the immense future iridium demand: first the dramatic reduction of iridium catalyst loading in PEM electrolysis cells and second the development of a recycling infrastructure for iridium catalysts with technical end-of-life recycling rates of at least 90%.

Industrial hydrogen production via alkaline water electrolysis (AEL) is a mature hydrogen production method. One argument in favor of AEL when supplied with renewable energy is its environmental superiority against conventional fossil-based hydrogen production. However today electricity from the national grid is widely utilized for industrial applications of AEL. Also the ban on asbestos membranes led to a change in performance patterns making a detailed assessment necessary. This study presents a comparative Life Cycle Assessment (LCA) using the GaBi software (version 6.115 thinkstep Leinfelden-Echterdingen Germany) revealing inventory data and environmental impacts for industrial hydrogen production by latest AELs (6 MW Zirfon membranes) in three different countries (Austria Germany and Spain) with corresponding grid mixes. The results confirm the dependence of most environmental effects from the operation phase and specifically the site-dependent electricity mix. Construction of system components and the replacement of cell stacks make a minor contribution. At present considering the three countries AEL can be operated in the most environmentally friendly fashion in Austria. Concerning the construction of AEL plants the materials nickel and polytetrafluoroethylene in particular used for cell manufacturing revealed significant contributions to the environmental burden.

The increasing feed-in of intermittent renewable energy sources into the electricity grids worldwide is currently leading to technical challenges. Stationary energy storage systems provide a cost-effective and efficient solution in order to facilitate the growing penetration of renewable energy sources. Major technical and economical challenges for energy storage systems are related to lifetime efficiency and monetary returns. Holistic simulation tools are needed in order to address these challenges before investing in energy storage systems. One of these tools is SimSES a holistic simulation framework specialized in evaluating energy storage technologies technically and economically. With a modular approach SimSES covers various topologies system components and storage technologies embedded in an energy storage application. This contribution shows the capabilities and benefits of SimSES by providing in-depth knowledge of the implementations and models. Selected functionalities are demonstrated with two use cases showing the easy-to-use simulation framework while providing detailed technical analysis for expert users. Hybrid energy storage systems consisting of lithium-ion and redox-flow batteries are investigated in a peak shaving application while various system topologies are analyzed in a frequency containment reserve application. The results for the peak shaving case study show a benefit in favor of the hybrid system in terms of overall cost and degradation behavior in applications that have a comparatively low energy throughput during lifetime. In terms of system topology a cascaded converter approach shows significant improvements in efficiency for the frequency containment reserve application.

With a growing need for replacing fossil fuels with cleaner alternatives hydrogen has emerged as a viable candidate for providing heat and power. However stable and safe combustion of hydrogen is not simple and as such a number of key issues have been identified that need to be understood for a safe design of combustion chambers. One such issue is the higher propensity of hydrogen flames to flashback compared to that for methane flames. The flashback problem is coupled with higher burner temperatures that could cause strong thermal stresses in burners and could hinder their performance. In order to systematically investigate flashback in premixed hydrogen-air flames for finding a global flashback criteria in this study we use numerical simulations as a basic tool to study flashback limits of slit burners. Flashback limits are found for varying geometrical parameters and equivalence ratios and the sensitivity of each parameter on the flashback limit and burner temperatures are identified and analyzed. It is shown that the conventional flashback correlation with critical velocity gradient does not collapse the flashback data as it does not take into account stretch induced preferential diffusion effects. A new Karlovitz number definition is introduced with physical insights that collapses the flashback data at all tested conditions in an excellent manner.

Alternative and especially renewable marine fuels are needed to reduce the environmental and climate impacts of the shipping sector. This paper investigates the business case for hydrogen as an alternative fuel in a new-built vessel utilizing fuel cells and liquefied hydrogen. A real option approach is used to model the optimal time and costs for investment as well as the value of deferring an investment as a result of uncertainty. This model is then used to assess the impact of a carbon tax on a ship owner’s investment decision. A low carbon tax results in ship owners deferring investments which then slows the uptake of the technology. We recommend that policymakers set a high carbon tax at an early stage in order to help hydrogen compete with fossil fuels. A clear and timely policy design promotes further investments and accelerates the uptake of new technologies that can fulfill decarbonization targets.

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.

In order to limit the effects of climate change the carbon dioxide emissions associated with the energy sector need to be reduced. Significant reductions can be achieved by using appropriate technologies and policies. In the context of recent discussions about climate change and energy transition this article critically reviews some technologies policies and frequently discussed solutions. The options for carbon emission reductions are grouped into (1) generation of secondary energy carriers (2) end-use energy sectors and (3) sector interdependencies. The challenges on the way to a decarbonized energy sector are identified with respect to environmental sustainability security of energy supply economic stability and social aspects. A global carbon tax is the most promising instrument to accelerate the process of decarbonization. Nevertheless this process will be very challenging for humanity due to high capital requirements the competition among energy sectors for decarbonization options inconsistent environmental policies and public acceptance of changes in energy use.

Since the 1970s hydrogen has been considered as a possible energy carrier for the storage of renewable energy. The main focus has been on addressing the ultimate challenge: developing an environmentally friendly successor for gasoline. This very ambitious goal has not yet been fully reached as discussed in this review but a range of new lightweight hydrogen-containing materials has been discovered with fascinating properties. State-of-the-art and future perspectives for hydrogen-containing solids will be discussed with a focus on metal borohydrides which reveal significant structural flexibility and may have a range of new interesting properties combined with very high hydrogen densities.