Austria

Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density low driving range and the higher propensity to deplete the energy storage before reaching the destination especially at low ambient temperatures. When the battery is depleted stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist however most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures) the thermal design for this specific application (available heat exchanger area zero vehicle speed air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system which is used in the Mobile Hydrogen Powersupply. Subsequently simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2 of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 436 °C. Furthermore the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery the highest possible ambient temperature is 42 °C. When the charging power is decreased operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements which are: sizing of fuel cell or battery trailer design and heat exchanger area operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.

Maximizing hydrogen utilization is crucial for improving the efficiency of proton exchange membrane (PEM) fuel cell systems. Ideally all supplied hydrogen reacts within the fuel cell. However nitrogen and water backdiffusion necessitate periodic purging of the anode recirculation path. Excessive purging leads to hydrogen losses while insufficient purging increases side reactions lowering fuel cell voltage and directly reducing effi ciency. This study investigates optimizing both hydrogen utilization and stack efficiency by adjusting purge valve actuation in a PEM fuel cell system. Results show that reducing purging from the reference increases hydrogen utilization by 0.79% points to 98.2% resulting in efficiency improvement of 0.72% points to 47.21% based on higher heating value. Moreover adjusting the purge valve actuation is the sole method for controlling the hydrogen stoichiometric ratio in ejector-based anode recirculation systems. Therefore precise purge valve operation is critical for maximizing both hydrogen utilization and PEM fuel cell efficiency.

The central role of hydrogen in the EU’s decarbonization strategy has increased the importance of critical raw materials. To address this the EU has taken legislative steps including the 2023 Critical Raw Materials Act (CRMA) to ensure a stable supply. Using a leader–follower Stackelberg game framework this study analyzes CRM market dynamics integrating CRMA compliance through rules on sourcing and stockpiling value chain resilience via the inclusion of supply diversification strategies and geopolitical influences by modeling exporter behaviors and trade dependencies. Results highlight the potential for strategic behavior by major exporters stressing the benefits of diversifying export sources and maintaining strategic stockpiles to stabilize supply. The findings provide insights into the EU’s efforts to secure CRM supplies key to achieving decarbonization goals and fostering a sustainable energy transition. Future research should explore alternative cost-reduction strategies mitigate exporter market power and evaluate the implications for pricing mechanisms market outcomes and consumer welfare

Energy systems increasingly rely on the synergistic operations of the electricity and hydrogen markets pursuing decarbonization. In this context it is necessary to develop tools capable of representing the interactions between these two markets to understand the role of hydrogen as an energy vector. This paper introduces a bi-level optimization model that captures the interactions between the electricity and hydrogen markets positioning hydrogen generators as strategic electricity price makers in the power market. The model can be efficiently solved and applied to real-world scenarios by reformulating it as a Mixed Integer Linear Program. The case studies analyze spot market behaviors when hydrogen generators are modeled as price makers in the electricity market. First single-period simulations reveal the effects of price-making and next a year-long simulation assesses broader implications. The findings demonstrate that conventional modeling assumptions such as the price-taker hydrogen generators in the electricity market and constant production cost hypothesis lead to non-optimal hydrogen generation strategies that raise electricity prices while reducing the profit of hydrogen generators and the hydrogen market social welfare. These results highlight the need for models that accurately reflect the interdependencies between these two energy markets.

To achieve deep decarbonization renewable energy generation must be substantially increased. The technologies with the lowest levelized cost of electricity (LCOE) are land-based photovoltaics (PVs) and wind energy. Agri-PVs offer the potential for dual land use combining energy generation with agricultural activities. However the costs of agri-PVs are higher than those of ground-mounted PV. To enhance the competitiveness of agri-PV we investigate the synergies between agri-PVs and hydrogen electrolysis through process simulation. Additionally we analyse current technological developments in agri-PVs based on a market analysis of start-up companies. Our results indicate that the levelized cost of hydrogen (LCOH) can be comparable for agri-PVs and ground-mounted PVs due to the somewhat smoother electricity generation for the same installed capacity. The market analysis reveals the emergence of a technology ecosystem that integrates agri-PVs with next-generation agricultural technologies such as sensors robotics and artificial intelligence (AI) agents along with localized electricity generation forecasting. The integrated agri-PV and hydrogen generation system has significant global scaling potential for renewable energy generation. Furthermore it positively impacts local economies and energy resilience may reduce water scarcity in agriculture and leverages advancements in AI robotics PV and hydrogen generation technologies.

This study investigates the effect of Oxygen-Enriched Combustion on hydrogen-enriched natural gas (H2 -NG) fuel mixtures at a semi-industrial scale (up to 60 kW). The analysis focuses on flame structure temperature distribu tion in the furnace NOx emissions and potential fuel savings. A multi-fuel multi-oxidizer jet burner was used to compare two oxygen enrichment configurations: premixed with air (PM) and air-pure O2 (AO) independent feed. The O2 -enriched flames remained stable across the entire fuel range. OH* chemiluminescence imaging for the H2 -NG fuel mixture delivering 50 concentration kW revealed that higher O2 increases the OH* intensity narrows and elongates the flame transitions from buoyancy- to momentum-driven shape and relocates the reaction zone. At 50 % oxygen enrichment level (OEL) flame shape OH* intensity and temperature profiles resembled pure O combustion. Up to 29 % OEL furnace temperature profiles were similar to those 2 of air-fuel combustion. The power required to maintain 1300 ± 25 ◦C at the reference position decreases with O2 enrichment. Higher OELs resulted in a sharp increase in NOx emissions. The effect of hydrogen enrichment on NOx levels was significantly less pronounced than that of oxygen enrichment. The rise in NOx emissions correlates with increased OH* in tensities. For a 50 % H2 2 blend increasing the O concentration in the oxidizer from 21 % to 50 % resulted in a 27 % reduction in flue gas heat losses. Utilizing O2 co-produced with H2 could be strategic for reducing fuel consumption facilitating the adoption of hydrogen-based energy systems.

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.

Japan has formulated a net-zero emissions target by 2050. Existing scenarios consistent with this target generally depend on carbon dioxide removal (CDR). In addition to domestic mitigation actions the import of low-carbon energy carriers such as hydrogen and synfuels and negative emissions credits are alternative options for achieving net-zero emissions in Japan. Although the potential and costs of these actions depend on global energy system transition characteristics which can potentially be informed by the global integrated assessment models they are not considered in current national scenario assessments. This study explores diverse options for achieving Japan's net-zero emissions target by 2050 using a national energy system model informed by international energy trade and emission credits costs estimated with a global energy system model. We found that demand-side electrification and approximately 100 Mt-CO2 per year of CDR implementation equivalent to approximately 10% of the current national CO2 emissions are essential across all net-zero emissions scenarios. Upscaling of domestically generated hydrogen-based alternative fuels and energy demand reduction can avoid further reliance on CDR. While imports of hydrogen-based energy carriers and emission credits are effective options annual import costs exceed the current cost of fossil fuel imports. In addition import dependency reaches approximately 50% in the scenario relying on hydrogen imports. This study highlights the importance of considering global trade when developing national net-zero emissions scenarios and describes potential new roles for global models.

Green hydrogen is an important technology in the energy transition with potential to decarbonize industrial processes increase renewable energy use and reduce reliance on fossil fuels yet it currently accounts for less than 1% of global hydrogen demand. One promising approach to expand production is the direct coupling of photovoltaic–electrolyzer systems. In this study overall and sub-system efficiencies were analyzed for different system setups coupling points and operating conditions such as temperature and irradiance. The highest overall system efficiencies were found to be more than 18%. The effect of varying irradiances on the coupled efficiency was not more than 5.7%. Different system designs optimized for different irradiances led to effects such as an increase in current density at the electrolyzer and thus an increase in the overvoltage which resulted in an overall efficiency loss of more than 3%. A key finding was that aligning the PV maximum power point with the electrolyzer polarization curve enables consistently high system efficiencies across the investigated irradiances. The findings were validated with two real life systems reproducing the coupling efficiencies of the model with 12%–14% including loss factors and approximately 18% for a direct coupled system respectively

To reduce fossil fuel dependency in shipping adopting alternative fuels and innovative propulsion systems is essential. Solid Oxide Fuel Cells (SOFC) powered by hydrogen carriers represent a promising solution. This study investigates a multi-fuel SOFC system for ocean-going vessels capable of operating with ammonia methanol or hydrogen thus enhancing bunkering flexibility. A thermodynamic model is developed to simulate the performance of a 3 kW small-scale system subsequently scaling up to a 10 MW configuration to meet the power demand of a container ship used as the case study. Results show that methanol is the most efficient fueling option reaching a system efficiency of 58% while ammonia and hydrogen reach slightly lower values of about 55% and 51% respectively due to higher auxiliary power consumption. To assess technical feasibility two installation scenarios are considered for accommodating multiple fuel tanks. The first scenario seeks the optimal fuel share equivalent to the diesel tank’s chemical energy (17.6 GWh) minimizing mass increase. The second scenario optimizes the fuel share within the available tank volume (1646 m3 ) again minimizing mass penalties. In both cases feasibility results have highlighted that changes are needed in terms of cargo reduction equal to 20.3% or alternatively in terms of lower autonomy with an increase in refueling stops. These issues can be mitigated by the benefits of increased bunkering flexibility