Austria

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria’s current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria’s total energy consumption. To decarbonize energy consumption a substantial increase in energy generation from renewable energy is required. This increase will add to the seasonality of energy supply and amplifies the seasonality in energy demand. In this paper the seasonality of energy supply and demand in a Net-Zero Scenario are analyzed for Austria and requirements for hydrogen storage derived. We looked into the potential usage of hydrogen in Austria and the economics of hydrogen generation and technology and market developments to assess the Levelized Cost of Hydrogen (LCOH). Then we cover the energy consumption in Austria followed by the REN potential. The results show that incremental potential of up to 140 TWh for hydropower photovoltaic (PV) and wind exists in Austria. Hydropower generation and PV is higher in summer- than in wintertime while wind energy leads to higher energy generation in wintertime. The largest incremental potential is PV with agrivoltaic systems significantly increasing the area amenable for PV compared with PV usage only. Battery Electric Vehicles (BEV) and Fuel Cell Vehicles (FCV) use energy more efficiently than Internal Combustion Engine (ICE) cars; however the use of hydrogen for electricity generation significantly decreases the efficiency due to electricity–hydrogen– electricity conversion. The increase in REN use and the higher demand for energy in Austria in wintertime require seasonal storage of energy. We developed three scenarios Externally Dependent Scenario (EDS) Balanced Energy Scenario (BES) or Self-Sustained Scenario (SSS) for Austria. The EDS scenario assumes significant REN import to Austria whereas the SSS scenario relies on REN generation within Austria. The required hydrogen storage would be 10.82 bn m3 for EDS 13.34 bn m3 for BES and 18.69 bn m3 for SSS. Gas and oil production in Austria and the presence of aquifers indicates that sufficient storage capacity might be available. Significant technology development is required to be able to implement hydrogen as an energy carrier and to balance seasonal energy demand and supply.

Achieving climate neutrality requires a massive transformation of current energy systems. Fossil energy sources must be replaced with renewable ones. Renewable energy sources with reasonable potential such as photovoltaics or wind power provide electricity. However since chemical energy carriers are essential for various sectors and applications the need for renewable gases comes more and more into focus. This paper determines the Austrian green hydrogen potential produced exclusively from electricity surpluses. In combination with assumed sustainable methane production the resulting renewable gas import demand is identified based on two fully decarbonised scenarios for the investigated years 2030 2040 and 2050. While in one scenario energy efficiency is maximised in the other scenario significant behavioural changes are considered to reduce the total energy consumption. A techno-economic analysis is used to identify the economically reasonable national green hydrogen potential and to calculate the averaged levelised cost of hydrogen (LCOH2) for each scenario and considered year. Furthermore roll-out curves for the necessary expansion of national electrolysis plants are presented. The results show that in 2050 about 43% of the national gas demand can be produced nationally and economically (34 TWh green hydrogen 16 TWh sustainable methane). The resulting national hydrogen production costs are comparable to the expected import costs (including transport costs). The most important actions are the quick and extensive expansion of renewables and electrolysis plants both nationally and internationally

The EU aims for complete decarbonisation. Therefore renewable generation must be massively expanded and the energy and exergy efficiency of the entire system must be significantly increased. To increase exergy efficiency a holistic consideration of the energy system is necessary. This work analyses the optimal technology mix to maximise exergy efficiency in a fully decarbonised energy system. An exergy-based optimisation model is presented and analysed. It considers both the energy supply system and the final energy application. The optimisation is using Austria as a case study with targeted renewable generation capacities of 2030. The results show that despite this massive expansion and the maximum exergy efficiency about half of the primary energy still be imported. Overall exergy efficiency can be raised from today's 34% (Sejkora et al. 2020) to 56%. The major increase in exergy efficiency is achieved in the areas of heat supply (via complete excess heat utilisation and heat pumps) and transport (via electric and fuel cell drives). The investigated exergy optimisation results in an increase of the final electrical energy demand by 44% compared to the current situation. This increase leads to mainly positive residual loads despite a significant expansion of renewable generation. Negative residual loads are used to provide heat and hydrogen.

Hydrogen is a key enabler of a sustainable society. Refurbishment of the existing natural gas infrastructure for up to 100% H2 is considered one of the most energy- and resource-efficient energy transportation methods. The question remains whether the transportation of 100% H2 with reasonable adaptions of the infrastructure and comparable energy amounts to natural gas is possible. The well-known critical components for refurbishment such as increased compressor power reduced linepack as well as pipeline transport efficiencies and their influencing factors were considered based on thermodynamic calculations with a step-by-step overview. A H2 content of 20–30% results in comparable operation parameters to pure natural gas. In addition to transport in pipelines decentralized H2 production will also play an important role in addressing future demands.

The maritime shipping sector is a major contributor to CO₂ emissions and this figure is expected to rise in coming decades. With the intent of reducing emissions from this sector this research proposes the utilization of the jet stream to transport a combination of cargo and hydrogen using airships or balloons at altitudes of 10–20 km. The jet streams flow in the mid-latitudes predominantly in a west–east direction reaching an average wind speed of 165 km/h. Using this combination of high wind speeds and reliable direction hydrogen-filled airships or balloons could carry hydrogen with a lower fuel requirement and shorter travel time compared to conventional shipping. Jet streams at different altitudes in the atmosphere were used to identify the most appropriate circular routes for global airship travel. Round-the-world trips would take 16 days in the Northern Hemisphere and 14 in the Southern Hemisphere. Hydrogen transport via the jet stream due to its lower energy consumption and shorter cargo delivery time access to cities far from the coast could be a competitive alternative to maritime shipping and liquefied hydrogen tankers in the development of a sustainable future hydrogen economy.

This review focuses on the reduction of iron oxides using hydrogen as a reducing agent. Due to increasing requirements from environmental issues a change of process concepts in the iron and steel industry is necessary within the next few years. Currently crude steel production is mainly based on fossil fuels and emitting of the climate-relevant gas carbon dioxide is integral. One opportunity to avoid or reduce greenhouse gas emissions is substituting hydrogen for carbon as an energy source and reducing agent. Hydrogen produced via renewable energies allows carbon-free reduction and avoids forming harmful greenhouse gases during the reduction process. The thermodynamic and kinetic behaviors of reduction with hydrogen are summarized and discussed in this review. The effects of influencing parameters such as temperature type of iron oxide grain size etc. are shown and compared with the reduction behavior of iron oxides with carbon monoxide. Different methods to describe the kinetics of the reduction progress and the role of the apparent activation energy are shown and proofed regarding their plausibility.

Pursued climate goals require reduced greenhouse gas emissions by substituting fossil fuels with energy from renewable sources in all energy-consuming processes. On a large-scale this can mainly be achieved through electricity from wind and sun which are subject to intermittency. To efficiently integrate this variable energy a coupling of the power sector to the residential transport industry and commercial/trade sector is often promoted called sector coupling (SC). Nevertheless our literature review indicates that SC is frequently misinterpreted and its scope varies among available research from exclusively considering the use of excess renewable electricity to a rather holistic view of integrated energy systems including excess heat or even biomass sources. The core objective of this article is to provide a thorough understanding of the SC concept through an analysis of its origin and its main purpose as described in the current literature. We provide a structured categorization of SC derived from our findings and critically discuss its remaining challenges as well as its value for renewable energy systems. We find that SC is rooted in the increasing use of variable renewable energy sources and its main assets are the flexibility it provides for renewable energy systems decarbonization potential for fossil-fuel-based end-consumption sectors and consequently reduced dependency on oil and gas extracting countries. However the enabling technologies face great challenges in their economic feasibility because of the uncertain future development of competing solutions.

A simulation tool called HYDRA to optimize individual hydrogen infrastructure layouts is presented. The different electrolyzer technologies namely proton exchange membrane electrolysis anion exchange membrane electrolysis alkaline electrolysis and solid oxide electrolysis as well as hydrogen storage possibilities are described in more detail and evaluated. To illustrate the application opportunities of HYDRA three project examples are discussed. The examples include central and decentral applications while taking the usage of hydrogen into account.

This article investigates the potential of renewable and low-carbon fuel production for the maritime shipping sector using Sweden as a case in focus. Techno-economic modelling and socio-technical transition studies are combined to explore the conditions opportunities and barriers to decarbonising the maritime shipping industry. A set of scenarios have been developed considering demand assumptions and potential instruments such as carbon price energy tax and blending mandate. The study finds that there are opportunities for decarbonising the maritime shipping industry by using renewable marine fuels such as advanced biofuels (e.g. biomethanol) electrofuels (e.g. e-methanol) and hydrogen. Sweden has tremendous resource potential for bio-based and hydrogen-based renewable liquid fuel production. In the evaluated system boundary biomethanol presents the cheapest technology option while e-ammonia is the most expensive one. Green electricity plays an important role in the decarbonisation of the maritime sector. The results of the supply chain optimisation identify the location sites and technology in Sweden as well as the trade flows to bring the fuels to where the bunker facilities are potentially located. Biomethanol and hydrogen-based marine fuels are cost-effective at a carbon price beyond 100 €/tCO2 and 200 €/tCO2 respectively. Linking back to the socio-technical transition pathways the study finds that some shipping companies are in the process of transitioning towards using renewable marine fuels thereby enabling niche innovations to break through the carbon lock-in and eventually alter the socio-technical regime while other shipping companies are more resistant. Overall there is increasing pressure from (inter)national energy and climate policy-making to decarbonise the maritime shipping industry.

To achieve the shift to renewable energies efficient energy storage is of the upmost importance. Hydrogen as a chemical energy storage represents a promising technology due to its high gravimetric energy density. However the most efficient form of hydrogen storage still remains an open question. Absorption-based storage of hydrogen in metal hydrides offers high volumetric energy densities as well as safety advantages. In this work technical economic and environmental aspects of different metal hydride materials are investigated. An overview of the material properties production methods as well as possibilities for enhancement of properties are presented. Furthermore impacts on material costs abundance of raw materials and dependency on imports are discussed. Advantages and disadvantages of selected materials are derived and may serve as a decision basis for material selection based on application. Further research on enhancement of material properties as well as on the system level is required for widespread application of metal hydrides.