Germany

Green hydrogen is a cornerstone in the global quest for a carbon-neutral future offering transformative potential for decarbonizing transportation. This study investigates its role by assessing the feasibility of a large-scale hydrogen refueling station in Germany focusing on integrating renewable energy sources. A hydrogen demand model with a 10-min time resolution to refuel 30 trucks and 20 vans (1019 kg/day) is combined with a techno-economic optimization model to evaluate a hybrid energy system utilizing wind solar and grid electricity. Scenario-based analysis reveals that Levelized Cost of Hydrogen ranges from 13.92 to 18.12 €/kg primarily influenced by electricity costs. Excess electricity sales can reduce this cost to 13.34–16.92 €/kg. On-site wind energy reduces storage and grid reliance achieving the lowest hydrogen cost. Unlike prior studies this work combines temporally resolved hydrogen demand profiles with comprehensive techno-economic modeling offering unprecedented insights into decentralized green hydrogen systems for heavy-duty transport. By bridging critical gaps in the scalability and economic feasibility of Power-to-Hydrogen systems it provides viable strategies for advancing green hydrogen infrastructure.

An important component of the deep decarbonization of the worldwide energy system is to build up the large-scale utilization of hydrogen to substitute for fossil fuels in all sectors including industry the electricity sector transportation and heating. Hence apart from reducing hydrogen production costs establishing an efficient and suitable infrastructure for the storage transportation and distribution of hydrogen becomes essential. This article provides a technically detailed overview of the state-of-the-art technologies for hydrogen infrastructure including the physical- and material-based hydrogen storage technologies. Physical-based storage means the storage of hydrogen in its compressed gaseous liquid or supercritical state. Hydrogen storage in the form of liquid-organic hydrogen carriers metal hydrides or power fuels is denoted as material-based storage. Furthermore primary ways to transport hydrogen such as land transportation via trailer and pipeline overseas shipping and some related commercial data are reviewed. As the key results of this article hydrogen storage and transportation technologies are compared with each other. This comparison provides recommendations for building appropriate hydrogen infrastructure systems according to different application scenarios.

Wind power-to-gas concepts have a high potential to sustainably cover the increasing demand for hydrogen as an energy carrier and raw material as it has been shown in the past that there is an enormous potential in energy overproduction which currently remains unused due to the shutdown of wind turbines. Thus there is barely experience in maritime production offshore storage and transport of large quantities of liquid hydrogen (LH2) due to the developing market. Instead tank designs refer to heavy standard onshore storage and transport applications with vacuum insulated double wall hulls made from austenitic stainless steel and comparatively high thermal diffusivity and conductivity. This reduces cost effectiveness due to inevitable boil-off and disregards some other requirements such as mechanical and cyclic strength and high corrosion resistance. Hence new concepts for LH2 tanks are required for addressing these issues. Two innovative technical concepts from space travel and high-temperature applications were adopted combined and qualified for use in the wind-power-to-gas scenario. The focus was particularly on the high requirements for transport weight insulation and cryogenic durability. The first concept part consisted of the implementation of FRP (fiber-reinforced plastics)–steel hybrid tanks which have a high potential as a hull for LH2 tanks. However these hybrid tanks are currently only used in the space sector. Questions still arise regarding interactions with coatings production material temperature resilience and design for commercial use. Thermally sprayed thermal barrier coatings (TBC) in turn show promising potential for surfaces subject to high thermal and mechanical stress. However the application is currently limited to use at high temperatures and needed to be extended to the cryogenic temperature range. The research on this second part of the concept thus focused on the validation of standard MCrAlY alloys and innovative (partially) amorphous metal coatings with regard to mechanical-technological and insulating properties in the low temperature range. This article gives an overview regarding the achieved results including manufacturing and measurements on a small tank demonstrator.

The green hydrogen economy is evolving rapidly accompanied by the need to establish trading routes on a global scale. Currently several technologies arecompeting for a leadership role in future hydrogen value chains. Within thiscontext liquid organic hydrogen carrier (LOHC) technology represents an excellent solution for large-scale storage and safe transportation of hydrogen.This article presents LOHC technology recent progress as well as further potential of this technology with focus on benzyltoluene as the carrier material.Furthermore this contribution offers an insight into previous and ongoingproject development activities led by Hydrogenious LOHC Technologies togetherwith an evaluation of the economic viability and an overview of the regulatory aspects of LOHC technology.

To enable a sustainable and socially accepted hydrogen and methanol economy it is crucial to prioritize green and water-conscious production. In this review we reveal that there is a significant research gap regarding comprehensive assessments of such production methods. We present an innovative process chain consisting of adsorption-based direct air capture solid oxide electrolysis and methanol synthesis to address this issue. To allow future comprehensive techno-economic assessments we perform a systematic literature review and harmonization of the techno-economic parameters of the process chain’s technologies. Based on the conducted literature review we find that the long-term median specific energy demand of adsorption-based direct air capture is expected to decrease to 204 kWhel/tCO2 and 1257 kWhth/tCO2 while the capture cost is expected to decrease to 162 €2024/tCO2 with a relative high uncertainty. The evaluated sources expect a future increase in system efficiency of solid oxide electrolysis to 80% while the purchase equipment costs are expected to decrease significantly. Finally we demonstrate the feasibility of the process chain from a technoeconomic perspective and show a potential reduction in external heat demand of the DAC unit of up to 34% when integrated in the process chain.

The high potential of hydrogen as a key factor on the pathway towards a climate neutral economy leads to rising demand in technical applications where gaseous hydrogen is used. For several metals hydrogen-metal interactions could cause a degradation of the material properties. This is especially valid for low carbon and highstrength structural steels as they are commonly used in natural gas pipelines and analyzed in this work. This work provides an insight to the impact of hydrogen on the mechanical properties of an API 5L X65 pipeline steel tested in 60 bar gaseous hydrogen atmosphere. The analyses were performed using the hollow specimen technique with slow strain rate testing (SSRT). The nature of the crack was visualized thereafter utilizing μCT imaging of the sample pressurized with gaseous hydrogen in comparison to one tested in an inert atmosphere. The combination of the results from non-conventional mechanical testing procedures and nondestructive imaging techniques has shown unambiguously how the exposure to hydrogen under realistic service pressure influences the mechanical properties of the material and the appearance of failure.

Green hydrogen has the potential to decarbonize hard-to-abate sectors and processes and should therefore play an important role in the energy system in achieving climate goals. However the main hydrogen supply is still based on fossil fuels and only limited amounts of electrolyzers have been installed. Switching from fossil-based fuel sources to green hydrogen is highly dependent on when and at what price green hydrogen will become available which in turn is dependent on the technological development of electrolyzers. In this paper we apply the experience curve methodology to project the capital expenditure and electrical consumption developments of the three main electrolysis technologies: alkaline proton exchange membrane and solid oxide electrolysis. Based on our calculations we expect that both AEL and PEM will reach similar costs by 2030 of around 300 e per kW and SOEC will remain the most expensive technology with a considerable cost reduction down to 828 e per kW. The electrical consumptions will fall to 4.23 kWh per Nm3 for AEL 3.86 kWh per Nm3 for PEM and 3.05 kWh per Nm3 for SOEC. Based on this technological progress we calculate that the levelized cost of hydrogen will be reduced to 2.43–3.07 e per kg. To reach lower levelized cost of hydrogen notable reductions in electricity (purchase) cost are required.

Hydrogen storage technologies are key enablers for the development of low-emission sustainable energy supply chains primarily due to the versatility of hydrogen as a clean energy carrier. Hydrogen can be utilized in both stationary and mobile power applications and as a lowenvironmental-impact energy source for various industrial sectors provided it is produced from renewable resources. However efficient hydrogen storage remains a significant technical challenge. Conventional storage methods such as compressed and liquefied hydrogen suffer from energy losses and limited gravimetric and volumetric energy densities highlighting the need for innovative storage solutions. One promising approach is hydrogen storage in metal hydrides which offers advantages such as high storage capacities and flexibility in the temperature and pressure conditions required for hydrogen uptake and release depending on the chosen material. However these systems necessitate the careful management of the heat generated and absorbed during hydrogen absorption and desorption processes. Thermal energy storage (TES) systems provide a means to enhance the energy efficiency and cost-effectiveness of metal hydride-based storage by effectively coupling thermal management with hydrogen storage processes. This review introduces metal hydride materials for hydrogen storage focusing on their thermophysical thermodynamic and kinetic properties. Additionally it explores TES materials including sensible latent and thermochemical energy storage options with emphasis on those that operate at temperatures compatible with widely studied hydride systems. A detailed analysis of notable metal hydride–TES coupled systems from the literature is provided. Finally the review assesses potential future developments in the field offering guidance for researchers and engineers in advancing innovative and efficient hydrogen energy systems.

Cryogenic liquid is often stored in a vacuum insulated Dewar vessel for a high efficiency of thermal insulation. Multi-layer insulation (MLI) can be further applied in the double-walled vacuum space to reduce the heat transfer from the environment to the stored cryogenic fluid. However in loss-of-vacuum accident (LOVA) scenarios heat flux across the MLI will raise to orders of magnitudes larger than with an intact vacuum shield. The cryogenic liquid will boil intensively and pressurize the vessel due to the heat ingress. The pressurization endangers the integrity of the vessel and poses an extra catastrophic risk if the vapor is flammable e.g. hydrogen. Therefore safety valves have to be designed and installed appropriately to make sure the pressure is limited to acceptable levels. In this work the dynamic process of the heat and mass transfers in the LOVA scenarios is studied theoretically. The mass deposition - desublimation of gaseous nitrogen on cryogenic surfaces is modeled as it provides the dominant contribution of the thermal load to the cryogenic fluid. The conventional heat convection and radiation are modeled too although they play only secondary roles as realized in the course of the study. The temperature dependent thermal properties of e.g. gaseous and solid nitrogen and stainless steel are used to improve the accuracy of calculation in the cryogenic temperature range. Presented methodology enabling the computation of thermodynamic parameters in the cryogenic storage system during LOVA scenarios provides further support for the future risk assessment and safety system design.

This study presents sector-coupled PyPSA-Earth: a novel global open-source energy system optimization model that incorporates major demand sectors and energy carriers in high spatial and temporal resolution to enable energy transition studies worldwide. The model includes a workflow that automatically downloads and processes the necessary demand supply and transmission data to co-optimize investment and operation of energy systems of countries or regions of Earth. The workflow provides the user with tools to forecast future demand scenarios and allows for custom user-defined data in several aspects. Sector-coupled PyPSA-Earth introduces novelty by offering users a comprehensive methodology to generate readily available sector-coupled data and model of any region worldwide starting from raw and open data sources. The model provides flexibility in terms of spatial and temporal detail allowing the user to tailor it to their specific needs. The capabilities of the model are demonstrated through two showcases for Egypt and Brazil. The Egypt case quantifies the relevant role of PV exceeding 35 GW and electrolysis in Suez and Damietta regions for meeting 16% of the EU hydrogen demand. Complementarily the Brazil case confirms the model’s ability in handling hydrogen planning infrastructure including repurposing of existing gas networks which results in 146 M€ lower costs than building new pipelines. The results prove the suitability of sector-coupled PyPSA-Earth to meet the needs of policymakers developers and scholars in advancing the energy transition. The authors invite the interested individuals and institutions to collaborate in the future developments of the model within PyPSA meets Earth initiative.