Austria
A Bird’s-Eye View on Polymer-Based Hydrogen Carriers for Mobile Applications
Oct 2022
Publication
Globally reducing CO2 emissions is an urgent priority. The hydrogen economy is a system that offers long-term solutions for a secure energy future and the CO2 crisis. From hydrogen production to consumption storing systems are the foundation of a viable hydrogen economy. Each step has been the topic of intense research for decades; however the development of a viable safe and efficient strategy for the storage of hydrogen remains the most challenging one. Storing hydrogen in polymer-based carriers can realize a more compact and much safer approach that does not require high pressure and cryogenic temperature with the potential to reach the targets determined by the United States Department of Energy. This review highlights an outline of the major polymeric material groups that are capable of storing and releasing hydrogen reversibly. According to the hydrogen storage results there is no optimal hydrogen storage system for all stationary and automotive applications so far. Additionally a comparison is made between different polymeric carriers and relevant solid-state hydrogen carriers to better understand the amount of hydrogen that can be stored and released realistically.
Hydrogen Deep Ocean Link: A Global Sustainable Interconnected Energy Grid
Mar 2022
Publication
The world is undergoing a substantial energy transition with an increasing share of intermittent sources of energy on the grid which is increasing the challenges to operate the power grid reliably. An option that has been receiving much focus after the COVID pandemic is the development of a hydrogen economy. Challenges for a hydrogen economy are the high investment costs involved in compression storage and long-distance transportation. This paper analyses an innovative proposal for the creation of hydrogen ocean links. It intends to fill existing gaps in the creation of a hydrogen economy with the increase in flexibility and viability for hydrogen production consumption compression storage and transportation. The main concept behind the proposals presented in this paper consists of using the fact that the pressure in the deep sea is very high which allows a thin and cheap HDPE tank to store and transport large amounts of pressurized hydrogen in the deep sea. This is performed by replacing seawater with pressurized hydrogen and maintaining the pressure in the pipes similar to the outside pressure. Hydrogen Deep Ocean Link has the potential of increasing the interconnectivity of different regional energy grids into a global sustainable interconnected energy system.
State-of-the-art Expansion Planning of Integrated Power, Natural Gas, and Hydrogen Systems
Apr 2022
Publication
Renewable hydrogen is considered key in the transition towards a carbon-neutral future. This is due to its spatio-temporal storage and sector coupling potential which has seen it referred to as energy vector. However many unresolved issues remain regarding hydrogen's large-scale deployment e.g. least-cost production optimal facility siting and overall implications on power and energy systems. Expansion planning provides an option to study these issues in the holistic context of energy systems. To this end this article presents a comprehensive review on state-of-the-art expansion planning models that consider integrated power natural gas and hydrogen systems. We cluster the existing literature in terms of modelling themes and scope study the applied systematic modelling characteristics and conduct an in-depth analysis of the technical model features regarding hydrogen technologies and natural gas infrastructure. Finally we identify and discuss research gaps in the existing literature.
Simulation-Assisted Determination of the Start-Up Time of a Polymer Electrolyte Fuel Cell
Nov 2021
Publication
Fuel starvation is a major cause of anode corrosion in low temperature polymer electrolyte fuel cells. The fuel cell start-up is a critical step as hydrogen may not yet be evenly distributed in the active area leading to local starvation. The present work investigates the hydrogen distribution and risk for starvation during start-up and after nitrogen purge by extending an existing computational fluid dynamic model to capture transient behavior. The results of the numerical model are compared with detailed experimental analysis on a 25 cm2 triple serpentine flow field with good agreement in all aspects and a required time step size of 1 s. This is two to three orders of magnitude larger than the time steps used by other works resulting in reasonably quick calculation times (e.g. 3 min calculation time for 1 s of experimental testing time using a 2 million element mesh).
Hydrogen Production by Methane Pyrolysis in Molten Binary Copper Alloys
Sep 2023
Publication
The utilization of hydrogen as an energy carrier and reduction agent in important industrial sectors is considered a key parameter on the way to a sustainable future. Steam reforming of methane is currently the most industrially used process to produce hydrogen. One major drawback of this method is the simultaneous generation of carbon dioxide. Methane pyrolysis represents a viable alternative as the basic reaction produces no CO2 but solid carbon besides hydrogen. The aim of this study is the investigation of different molten copper alloys regarding their efficiency as catalytic media for the pyrolysis of methane in an inductively heated bubble column reactor. The conducted experiments demonstrate a strong influence of the catalyst in use on the one hand on the conversion rate of methane and on the other hand on the properties of the produced carbon. Optimization of these parameters is of crucial importance to achieve the economic competitiveness of the process.
Refurbishment of Natural Gas Pipelines towards 100% Hydrogen—A Thermodynamic-Based Analysis
Dec 2022
Publication
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.
Green Hydrogen-Based Direct Reduction for Low-Carbon Steelmaking
May 2020
Publication
The European steel industry aims at a CO2 reduction of 80–95% by 2050 ensuring that Europe will meet the requirements of the Paris Agreement. As the reduction potentials of the current steelmaking routes are low the transfer toward breakthrough-technologies is essential to reach these goals. Hydrogen-based steelmaking is one approach to realize CO2-lean steelmaking. Therefore the natural gas (NG)-based direct reduction (DR) acts as a basis for the first step of this transition. The high flexibility of this route allows the gradual addition of hydrogen and in a long-term view runs the process with pure hydrogen. Model-based calculations are performed to assess the possibilities for injecting hydrogen. Therefore NG- and hydrogen-based DR models are developed to create new process know-how and enable an evaluation of these processes in terms of energy demand CO2-reduction potentials and so on. The examinations show that the hydrogen-based route offers a huge potential for green steelmaking which is strongly depending on the carbon footprint of the electricity used for the production of hydrogen. Only if the carbon intensity is less than about 120 g CO2 kWh1 the hydrogen-based process emits less CO2 than the NG-based DR process.
The Economics and the Environmental Benignity of Different Colors of Hydrogen
Feb 2022
Publication
Due to the increasing greenhouse gas emissions as well as due to the rapidly increasing use of renewable energy sources in the electricity generation over the last years interest in hydrogen is rising again. Hydrogen can be used as a storage for renewable energy balancing the whole energy systems and contributing to the decarbonization of the energy system especially of the industry and the transport sector. The major objective of this paper is to discuss various ways of hydrogen production depending on the primary energy sources used. Moreover the economic and environmental performance of three major hydrogen colors as well as major barriers for faster deployment in fuel cell vehicles are analyzed. The major conclusion is that the full environmental benefits of hydrogen use are highly dependent on the hydrogen production methods and primary sources used. Only green hydrogen with electricity from wind PV and hydro has truly low emissions. All other sources like blue hydrogen with CCUS or electrolysis using the electricity grid have substantially higher emissions coming close to grey hydrogen production. Another conclusion is that it is important to introduce an international market for hydrogen to lower costs and to produce hydrogen where conditions are best. Finally the major open question remaining is whether e including all external costs of all energy carriers hydrogen of any color may become economically competitive in any sector of the energy system. The future success of hydrogen is very dependent on technological development and resulting cost reductions as well as on future priorities and the corresponding policy framework. The policy framework should support the shift from grey to green hydrogen.
Achieving Carbon-neutral Iron and Steelmaking in Europe Through the Deployment of Bioenergy with Carbon Capture and Storage
Jan 2019
Publication
The 30 integrated steel plants operating in the European Union (EU) are among the largest single-point CO2 emitters in the region. The deployment of bioenergy with carbon capture and storage (bio-CCS) could significantly reduce their emission intensities. In detail the results demonstrate that CO2 emission reduction targets of up to 20% can be met entirely by biomass deployment. A slow CCS technology introduction on top of biomass deployment is expected as the requirement for emission reduction increases further. Bio-CCS could then be a key technology particularly in terms of meeting targets above 50% with CO2 avoidance costs ranging between €60 and €100 tCO2−1 at full-scale deployment. The future of bio-CCS and its utilisation on a larger scale would therefore only be viable if such CO2 avoidance cost were to become economically appealing. Small and medium plants in particular would economically benefit from sharing CO2 pipeline networks. CO2 transport however makes a relatively small contribution to the total CO2 avoidance cost. In the future the role of bio-CCS in the European iron and steelmaking industry will also be influenced by non-economic conditions such as regulations public acceptance realistic CO2 storage capacity and the progress of other mitigation technologies.
Assessment and Recommendations for a Fossil Free Future for Track Work Machinery
Oct 2021
Publication
Current railway track work machinery is mainly operated with diesel fuel. As a result track maintenance of Austrian Federal Railways (OeBB) amounts to nearly 9000 t CO2 equivalent per year according to calculations from Graz University of Technology. OeBB’s total length of railway lines only accounts for 0.56% of the world’s length of lines. This indicates huge potential for mitigating greenhouse gas emissions considering the need for track maintenance worldwide. Environmental concerns have led to the introduction of alternative drives in the transport sector. Until now R&D (Research & Development) of alternative propulsion technologies for track work machinery has been widely neglected. This paper examines the possibility of achieving zero direct emissions during maintenance and construction work in railways by switching to alternative drives. The goal is to analyze alternative propulsion solutions arising from the transport sector and to assess their applicability to track work machinery. Research results together with a calculation tool show that available battery technology is recommendable for energy demands lower than 300 kWh per construction shift. Hydrogen fuel cell technology is an alternative for energy demands higher than 800 kWh. For machinery with energy requirements in between enhancements in battery technology are necessary and desirable for the coming years.
Role of Grain Boundaries in Hydrogen Embrittlement of Alloy 725: Single and Bi-crystal Microcantilever Bending Study
Jan 2022
Publication
In situ electrochemical microcantilever bending tests were conducted in this study to investigate the role of grain boundaries (GBs) in hydrogen embrittlement (HE) of Alloy 725. Specimens were prepared under three different heat treatment conditions and denoted as solution-annealed (SA) aged (AG) and over-aged (OA) samples. For single-crystal beams in an H-containing environment all three heat-treated samples exhibited crack formation and propagation; however crack propagation was more severe in the OA sample. The anodic extraction of H presented similar results as those under the H-free condition indicating the reversibility of the H effect under the tested conditions. Bi-crystal micro-cantilevers bent under H-free and H-charged conditions revealed the significant role of the GB in the HE of the beams. The results indicated that the GB in the SA sample facilitated dislocation dissipation whereas for the OA sample it caused the retardation of crack propagation. For the AG sample testing in an H-containing environment led to the formation of a sharp severe crack along the GB path.
Underground Hydrogen Storage: Application of Geochemical Modelling in a Case Study in the Molasse Basin, Upper Austria
Feb 2019
Publication
Hydrogen storage in depleted gas fields is a promising option for the large-scale storage of excess renewable energy. In the framework of the hydrogen storage assessment for the “Underground Sun Storage” project we conduct a multi-step geochemical modelling approach to study fluid–rock interactions by means of equilibrium and kinetic batch simulations. With the equilibrium approach we estimate the long-term consequences of hydrogen storage whereas kinetic models are used to investigate the interactions between hydrogen and the formation on the time scales of typical storage cycles. The kinetic approach suggests that reactions of hydrogen with minerals become only relevant over timescales much longer than the considered storage cycles. The final kinetic model considers both mineral reactions and hydrogen dissolution to be kinetically controlled. Interactions among hydrogen and aqueous-phase components seem to be dominant within the storage-relevant time span. Additionally sensitivity analyses of hydrogen dissolution kinetics which we consider to be the controlling parameter of the overall reaction system were performed. Reliable data on the kinetic rates of mineral dissolution and precipitation reactions specifically in the presence of hydrogen are scarce and often not representative of the studied conditions. These uncertainties in the kinetic rates for minerals such as pyrite and pyrrhotite were investigated and are discussed in the present work. The proposed geochemical workflow provides valuable insight into controlling mechanisms and risk evaluation of hydrogen storage projects and may serve as a guideline for future investigations.
Role of Hydrogen-based Energy Carriers as an Alternative Option to Reduce Residual Emissions Associated with Mid-century Decarbonization Goals
Mar 2022
Publication
Hydrogen-based energy carriers including hydrogen ammonia and synthetic hydrocarbons are expected to help reduce residual carbon dioxide emissions in the context of the Paris Agreement goals although their potential has not yet been fully clarified in light of their competitiveness and complementarity with other mitigation options such as electricity biofuels and carbon capture and storage (CCS). This study aimed to explore the role of hydrogen in the global energy system under various mitigation scenarios and technology portfolios using a detailed energy system model that considers various energy technologies including the conversion and use of hydrogen-based energy carriers. The results indicate that the share of hydrogen-based energy carriers generally remains less than 5% of global final energy demand by 2050 in the 2 ◦C scenarios. Nevertheless such carriers contribute to removal of residual emissions from the industry and transport sectors under specific conditions. Their share increases to 10–15% under stringent mitigation scenarios corresponding to 1.5 ◦C warming and scenarios without CCS. The transport sector is the largest consumer accounting for half or more of hydrogen production followed by the industry and power sectors. In addition to direct usage of hydrogen and ammonia synthetic hydrocarbons converted from hydrogen and carbon captured from biomass or direct air capture are attractive transport fuels growing to half of all hydrogen-based energy carriers. Upscaling of electrification and biofuels is another common cost-effective strategy revealing the importance of holistic policy design rather than heavy reliance on hydrogen.
Exergy as Criteria for Efficient energy Systems - Maximising Energy Efficiency from Resource to Energy Service, an Austrian Case Study
Sep 2021
Publication
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.
Energy Management of Heavy-duty Fuel Cell Vehicles in Real-world Driving Scenarios: Robust Design of Strategies to Maximize the Hydrogen Economy and System Lifetime
Feb 2021
Publication
Energy management is a critical issue for the advancement of fuel cell vehicles because it significantly influences their hydrogen economy and lifetime. This paper offers a comprehensive investigation of the energy management of heavy-duty fuel cell vehicles for road freight transportation. An important and unique contribution of this study is the development of an extensive and realistic representation of the vehicle operation which includes 1750 hours of real-world driving data and variable truck loading conditions. This framework is used to analyze the potential benefits and drawbacks of heuristic optimal and predictive energy management strategies to maximize the hydrogen economy and system lifetime of fuel cell vehicles for road freight transportation. In particular the statistical evaluation of the effectiveness and robustness of the simulation results proves that it is necessary to consider numerous and realistic driving scenarios to validate energy management strategies and obtain a robust design. This paper shows that the hydrogen economy can be maximized as an individual target using the available driving information achieving a negligible deviation from the theoretical limit. Furthermore this study establishes that heuristic and optimal strategies can significantly reduce fuel cell transients to improve the system lifetime while retaining high hydrogen economies. Finally this investigation reveals the potential benefits of predictive energy management strategies for the multi-objective optimization of the hydrogen economy and system lifetime.
Mid-century Net-zero Emissions Pathways for Japan: Potential Roles of Global Mitigation Scenarios in Informing National Decarbonisation Strategies
Jan 2024
Publication
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.
Porosity and Thickness Effect of Pd–Cu–Si Metallic Glasses on Electrocatalytic Hydrogen Production and Storage
Aug 2021
Publication
This contribution places emphasis on tuning pore architecture and film thickness of mesoporous Pd–Cu–Si thin films sputtered on Si/SiO2 substrates for enhanced electrocatalytic and hydrogen sorption/desorption activity and their comparison with the state-of-the-art thin film electrocatalysts. Small Tafel slope of 43 mV dec–1 for 1250 nm thick coatings with 2 µm diameter pores with 4.2 µm interspacing (H2) electrocatalyst with comparable hydrogen overpotentials to the literature suggests its use for standard fuel cells. The largest hydrogen sorption has been attained for the 250 nm thick electrocatalyst on 5 µm pore diameter and 12 µm interspacing (2189 µC cm–2 per CV cycle) making it possible for rapid storage systems. Moreover the charge transfer resistance described by an equivalent circuit model has an excellent correlation with Tafel slopes. Along with its very low Tafel slope of 42 mV dec–1 10 nm thick H2 pore design electrocatalyst has the highest capacitive response of ∼0.001 S sn cm–2 and is promising to be used as a nano-charger and hydrogen sensor.
Expectations as a Key to Understanding Actor Strategies in the Field of Fuel Cell and Hydrogen Vehicles
Feb 2012
Publication
Due to its environmental impact the mobility system is increasingly under pressure. The challenges to cope with climate change air quality depleting fossil resources imply the need for a transition of the current mobility system towards a more sustainable one. Expectations and visions have been identified as crucial in the guidance of such transitions and more specifically of actor strategies. Still it remained unclear why the actors involved in transition activities appear to change their strategies frequently and suddenly. The empirical analysis of the expectations and strategies of three actors in the field of hydrogen and fuel cell technology indicates that changing actor strategies can be explained by rather volatile expectations related to different levels. Our case studies of the strategies of two large car manufacturers and the German government demonstrate that the car manufacturers refer strongly to expectations about the future regime while expectations related to the socio-technical landscape level appear to be crucial for the strategy of the German government.
Interlinking the Renewable Electricity and Gas Sectors: A Techno-Economic Case Study for Austria
Oct 2021
Publication
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
Air Mass Flow and Pressure Optimisation of a PEM Fuel Cell Range Extender System
Aug 2022
Publication
In order to eliminate the local CO2 emissions from vehicles and to combat the associated climate change the classic internal combustion engine can be replaced by an electric motor. The two most advantageous variants for the necessary electrical energy storage in the vehicle are currently the purely electrochemical storage in batteries and the chemical storage in hydrogen with subsequent conversion into electrical energy by means of a fuel cell stack. The two variants can also be combined in a battery electric vehicle with a fuel cell range extender so that the vehicle can be refuelled either purely electrically or using hydrogen. The air compressor a key component of a PEM fuel cell system can be operated at different air excess and pressure ratios which influence the stack as well as the system efficiency. To asses the steady state behaviour of a PEM fuel cell range extender system a system test bench utilising a commercially available 30 kW stack (96 cells 409 cm2 cell area) was developed. The influences of the operating parameters (air excess ratio 1.3 to 1.7 stack temperature 20 °C–60 °C air compressor pressure ratio up to 1.67 load point 122 mA/cm2 to 978 mA/cm2) on the fuel cell stack voltage level (constant ambient relative humidity of 45%) and the corresponding system efficiency were measured by utilising current voltage mass flow temperature and pressure sensors. A fuel cell stack model was presented which correlates closely with the experimental data (0.861% relative error). The air supply components were modelled utilising a surface fit. Subsequently the system efficiency of the validated model was optimised by varying the air mass flow and air pressure. It is shown that higher air pressures and lower air excess ratios increase the system efficiency at high loads. The maximum achieved system efficiency is 55.21% at the lowest continuous load point and 43.74% at the highest continuous load point. Future work can utilise the test bench or the validated model for component design studies to further improve the system efficiency.
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