Germany
Fostering Macroeconomic Research on Hydrogen-Powered Aviation: A Systematic Literature Review on General Equilibrium Models
Feb 2023
Publication
Hydrogen is a promising fuel to decarbonize aviation but macroeconomic studies are currently missing. Computable general equilibrium (CGE) models are suitable to conduct macroeconomic analyses and are frequently employed in hydrogen and aviation research. The main objective of this paper is to investigate existing CGE studies related to (a) hydrogen and (b) aviation to derive a macroeconomic research agenda for hydrogen-powered aviation. Therefore the well-established method of systematic literature review is conducted. First we provide an overview of 18 hydrogen-related and 27 aviation-related CGE studies and analyze the literature with respect to appropriate categories. Second we highlight key insights and identify research gaps for both the hydrogen and aviation-related CGE literature. Our findings comprise inter alia hydrogen’s current lack of cost competitiveness and the macroeconomic relevance of air transportation. Research gaps include among others a stronger focus on sustainable hydrogen and a more holistic perspective on the air transportation system. Third we derive implications for macroeconomic research on hydrogen-powered aviation including (I) the consideration of existing modeling approaches (II) the utilization of interdisciplinary data and scenarios (III) geographical suitability (IV) the application of diverse policy tools and (V) a holistic perspective. Our work contributes a meaningful foundation for macroeconomic studies on hydrogen-powered aviation. Moreover we recommend policymakers to address the macroeconomic perspectives of hydrogen use in air transportation.
Sector Coupling and Business Models Towards Sustainability: The Case of the Hydrogen Vehicle Industry
Mar 2022
Publication
The concept of sector coupling has been gaining increased momentum in political discourses during 18 the past few years but it has only recently received the attention of international academics. The 19 private sector is particularly relevant to foster sector coupling through entrepreneurial action – 20 specifically innovative business models for more sustainable technologies are needed to promote a 21 transition towards more sustainability. So far however the literature on business models from a 22 sector coupling perspective is scarce yet strongly emerging. To address the identified research gaps 23 and enhance the current knowledge on the emerging hydrogen vehicle industry and sector coupling 24 this study adopts a qualitative and exploratory research approach and builds on information gained 25 in 103 semi-structured interviews to discuss emerging business models in Germany. In particular 33 26 business cases have been analyzed. Anchoring business model theory to the concept of sector 27 coupling this study identifies 12 business model archetypes in the emerging hydrogen vehicle 28 industry and its value chain. It can be shown that while the market is still emerging and the market 29 players are not defined and are evolving companies are currently engaged in finding their position 30 along the value chain fostering vertical integration and promoting cooperation between the 31 different sectors. While this study is relevant for both the academia and the industry it is particularly 2 32 interesting for policy makers shaping the future of sustainable development specifically considering 33 integrated energy systems.
Underground Bio-methanation: Concept and Potential
Feb 2020
Publication
As a major part of the energy turn around the European Union and other countries are supporting the development of renewable energy technologies to decrease nuclear and fossil energy production. Therefore efficient use of renewable energy resources is one challenge as they are influenced by environmental conditions and hence the intensity of resources such as wind or solar power fluctuates. To secure constant energy supply suitable energy storage and conversion techniques are required. An upcoming solution is the utilization and storage of hydrogen or hydrogen-rich natural gas in porous formations in the underground. In the past microbial methanation was observed as a side effect during these gas storage operations. The concept of underground bio-methanation arised which uses the microbial metabolism to convert hydrogen and carbon dioxide into methane. The concept consists of injecting gaseous hydrogen and carbon dioxide into an underground structure during energy production peaks which are subsequently partly converted into methane. The resulting methane-rich gas mixture is withdrawn during high energy demand. The concept is comparable to engineered bio-reactors which are already locally integrated into the gas infrastructure. In both technologies the conversion process of hydrogen into methane is driven by hydrogenotrophic methanogenic archaea present in the aqueous phase of the natural underground or above-ground engineered reactor. Nevertheless the porous medium in the underground provides compared to the engineered bio-reactors a larger interface between the gas and aqueous phase caused by the enormous volume in the underground porous media. The following article summarizes the potential and concept of underground methanation and the current state of the art in terms of laboratory investigations and pilot tests. A short system potential analysis shows that an underground bio-reactor with a storage capacity of 850 Mio. Sm3 could deliver methane to more than 600000 households based on a hydrogen production from renewable energies.
Green Hydrogen Production Potential in West Africa – Case of Niger
Jul 2022
Publication
Niger offers the possibility of producing green hydrogen due to its high solar energy potential. Due to the still growing domestic oil and coal industry the use of green hydrogen in the country currently seems unlikely at the higher costs of hydrogen as an energy vector. However the export of green hydrogen to industrialized countries could be an option. In 2020 a hydrogen partnership has been established between Germany and Niger. The potential import of green hydrogen represents an option for Germany and other European countries to decarbonize domestic energy supply. Currently there are no known projects for the electrolytic production of hydrogen in Niger. In this work potential hydrogen demand across electricity and transport sectors is forecasted until 2040. The electricity demand in 2040 is expected at 2934 GWh and the gasoline and diesel demand at 964 m3 and 2181 m3 respectively. Accordingly the total hydrogen needed to supply electricity and the transport sector (e.g. to replace 1% gasoline and diesel demand in 2040) is calculated at 0.0117 Mt. Only a small fraction of 5% of the land area in Niger would be sufficient to generate the required electricity from solar PV to produce hydrogen.
Biological CO2-Methanation: An Approach to Standardization
May 2019
Publication
Power-to-Methane as one part of Power-to-Gas has been recognized globally as one of the key elements for the transition towards a sustainable energy system. While plants that produce methane catalytically have been in operation for a long time biological methanation has just reached industrial pilot scale and near-term commercial application. The growing importance of the biological method is reflected by an increasing number of scientific articles describing novel approaches to improve this technology. However these studies are difficult to compare because they lack a coherent nomenclature. In this article we present a comprehensive set of parameters allowing the characterization and comparison of various biological methanation processes. To identify relevant parameters needed for a proper description of this technology we summarized existing literature and defined system boundaries for Power-to-Methane process steps. On this basis we derive system parameters providing information on the methanation system its performance the biology and cost aspects. As a result three different standards are provided as a blueprint matrix for use in academia and industry applicable to both biological and catalytic methanation. Hence this review attempts to set the standards for a comprehensive description of biological and chemical methanation processes.
Simulation of Hydrogen Mixing and Par Operation During Accidental Release in an LH2 Carrier Engine Room
Sep 2021
Publication
Next-generation LH2 carriers may use the boil-off gas from the cargo tanks as additional fuel for the engine. As a consequence hydrogen pipes will enter the room of the ship’s propulsion system and transport hydrogen to the main engine. The hydrogen distribution resulting from a postulated hydrogen leak inside the room of the propulsion system has been analyzed by means of Computational Fluid Dynamics (CFD). In a subsequent step simulations with passive auto-catalytic recombiners (PARs) were carried out in order to investigate if the recombiners can increase the safety margins during such accident scenarios. CFD enables a 3D prediction of the transient distribution with a high resolution allowing to identify local accumulation of hydrogen and consequently to identify optimal PAR positions as well as to demonstrate the efficiency of the PARs. The simulation of the unmitigated reference case reveals a strong natural circulation driven by the density difference of hydrogen and the incoming cold air from the ventilation system. Globally this natural circulation dilutes the hydrogen and removes a considerable amount from the room of the ship’s propulsion system via the ventilation ducts. However a hydrogen accumulation beyond the flammability limit is identified below the first ceiling above the leak position and the back-side wall of the engine room. Based on these findings suitable positions for recombiners were identified. The design objectives of the PAR system were on the one hand to provide both high instantaneous and integral removal rate and on the other hand to limit build-up of flammable clouds by means of depletion and PAR induced mixing processes. The simulations performed with three different PAR arrangements (variation of large and<br/>small PAR units at different positions) confirm that the PARs reduce efficiently the hydrogen<br/>accumulations.
Law and Policy Review on Green Hydrogen Potential in ECOWAS Countries
Mar 2022
Publication
This paper aims to review existing energy-sector and hydrogen-energy-related legal policy and strategy documents in the ECOWAS region. To achieve this aim current renewable-energyrelated laws acts of parliament executive orders presidential decrees administrative orders and memoranda were analyzed. The study shows that ECOWAS countries have strived to design consistent legal instruments regarding renewable energy in developing comprehensive legislation and bylaws to consolidate it and to encourage investments in renewable energy. Despite all these countries having a legislative basis for regulating renewable energy there are still weaknesses that revolve around the law and policy regarding its possible application in green hydrogen production and use. The central conclusion of this review paper is that ECOWAS member states presently have no official hydrogen policies nor bylaws in place. The hydrogen rise presents a challenge and opportunity for members to play an important role in the fast-growing global hydrogen market. Therefore these countries need to reform their regulatory frameworks and align their policies by introducing green hydrogen production in order to accomplish their green economy transition for the future and to boost the continent’s sustainable development.
Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies
Jul 2020
Publication
The economic and ecological production of green hydrogen by water electrolysis is one of the major challenges within Carbon2Chem and other power-to-X projects. This paper presents an evaluation of the different water electrolysis technologies with respect to their specific energy demand carbon footprint and the forecast production costs in 2030. From a current perspective alkaline water electrolysis is evaluated as the most favorable technology for the cost-effective production of low-carbon hydrogen with fluctuating renewables.
The More the Merrier? Actors and Ideas in the Evolution of Germany Hydrogen Policy Discourse
Feb 2023
Publication
Hydrogen has set high hopes for decarbonization due to its flexibility and ability to decarbonize sectors of the economy where direct electrification appears unviable. Broad hydrogen policies have therefore started to emerge. Nevertheless it is still a rather niche technology not integrated or adopted at scale and not regulated through particular policy provisions. The involved stakeholders are thus still rushing to set the agenda over the issue. All this plays out publicly and shapes the public discourse. This paper explores how the composition of stakeholders their positions and the overall discourse structure have developed and accompanied the political agenda-setting in the early public debate on hydrogen in Germany. We use discourse network analysis of media where stakeholders' claims-making is documented and their positions can be tracked over time. The public discourse on hydrogen in Germany shows the expected evolution of statements in connection with the two milestones chosen for the analyses the initiation of the Gas 2030 Dialogue and the publication of the National Hydrogen Strategy. Interestingly the discourse was comparatively feeble in the immediate aftermath of the respective milestones but intensified in a consolidation phase around half a year later. Sequencing the discourse and contextualizing its content relative to political societal and economic conditions in a diachronic way is essential because it helps to avoid misinterpreting the development of stakeholders' standpoints as conflict-driven rather than mere repositioning. Thus we observed no discourse “polarization” even though potentially polarizing issues were already present in the debate.
Design of Fuel Cell Systems for Aviation: Representative Mission Profiles and Sensitivity Analyses
Apr 2019
Publication
The global transition to a clean and sustainable energy infrastructure does not stop at aviation. The European Commission defined a set of environmental goals for the “Flight Path 2050”: 75% CO2 reduction 90% NOx reduction and 65% perceived noise reduction. Hydrogen as an energy carrier fulfills these needs while it would also offer a tenable and flexible solution for intermittent large-scale energy storage for renewable energy networks. If hydrogen is used as an energy carrier there is no better device than a fuel cell to convert its stored chemical energy. In order to design fuel cell systems for passenger aircraft it is necessary to specify the requirements that the system has to fulfill. In this paper a statistical approach to analyze these requirements is presented which accounts for variations in the flight mission profile. Starting from a subset of flight data within the desired class (e.g. mid-range inter-European flights) a stochastic model of the random mission profile is inferred. This model allows for subsequent predictions under uncertainty as part of the aircraft design process. By using Monte Carlo-based sampling of flight mission profiles the range of necessary component sizes as well as optimal degrees of hybridization with a battery is explored and design options are evaluated. Furthermore Monte Carlo-based sensitivity analysis of performance parameters explores the potential of future technological developments. Results suggest that the improvement of the specific power of the fuel cell is the deciding factor for lowering the energy system mass. The specific energy of the battery has a low influence but acts in conjunction with the specific power of the fuel cell.
Life Cycle Costing Approaches of Fuel Cell and Hydrogen Systems: A Literature Review
Apr 2023
Publication
Hydrogen is a versatile energy carrier which can be produced from variety of feedstocks stored and transported in various forms for multi-functional end-uses in transportation energy and manufacturing sectors. Several regional national and supra-national climate policy frameworks emphasize the need value and importance of Fuel cell and Hydrogen (FCH) technologies for deep and sector-wide decarbonization. Despite these multi-faceted advantages familiar and proven FCH technologies such as alkaline electrolysis and proton-exchange membrane fuel cell (PEMFC) often face economic technical and societal barriers to mass-market adoption. There is no single unified standardized and globally harmonized normative definition of costs. Nevertheless the discussion and debates surrounding plausible candidates and/or constituents integral for assessing the economics and value proposition of status-quo as well as developmental FCH technologies are steadily increasing—Life Cycle Costing (LCC) being one of them if not the most important outcome of such exercises.<br/>To that end this review article seeks to improve our collective understanding of LCC of FCH technologies by scrutinizing close to a few hundred publications drawn from representative databases—SCOPUS and Web of Science encompassing several tens of technologies for production and select transportation storage and end-user utilization cases. This comprehensive review forms part of and serves as the basis for the Clean Hydrogen Partnership funded SH2E project whose ultimate goal is the methodical development a formal set of principles and guardrails for evaluating the economic environmental and social impacts of FCH technologies. Additionally the SH2E projects will also facilitate the proper comparison of different FCH technologies whilst reconciling range of technologies methodologies modelling assumptions and parameterization found in existing literature.
Power Sector Effects of Green Hydrogen Production in Germany
Aug 2023
Publication
The use of green hydrogen can support the decarbonization of sectors which are difficult to electrify such as industry or heavy transport. Yet the wider power sector effects of providing green hydrogen are not well understood so far. We use an open-source electricity sector model to investigate potential power sector interactions of three alternative supply chains for green hydrogen in Germany in the year 2030. We distinguish between model settings in which Germany is modeled as an electric island versus embedded in an interconnected system with its neighboring countries as well as settings with and without technology-specific capacity bounds on wind energy. The findings suggest that large-scale hydrogen storage can provide valuable flexibility to the power system in settings with high renewable energy shares. These benefits are more pronounced in the absence of flexibility from geographical balancing. We further find that the effects of green hydrogen production on the optimal generation portfolio strongly depend on the model assumptions regarding capacity expansion potentials. We also identify a potential distributional effect of green hydrogen production at the expense of other electricity consumers of which policy makers should be aware.
Energy System Changes in 1.5 °C, Well Below 2 °C and 2 °C Scenarios
Dec 2018
Publication
Meeting the Paris Agreement's goal to limit global warming to well below 2 °C and pursuing efforts towards 1.5 °C is likely to require more rapid and fundamental energy system changes than the previously-agreed 2 °C target. Here we assess over 200 integrated assessment model scenarios which achieve 2 °C and well-below 2 °C targets drawn from the IPCC's fifth assessment report database combined with a set of 1.5 °C scenarios produced in recent years. We specifically assess differences in a range of near-term indicators describing CO2 emissions reductions pathways changes in primary energy and final energy across the economy's major sectors in addition to more detailed metrics around the use of carbon capture and storage (CCS) negative emissions low-carbon electricity and hydrogen.
Technology Transfer from Fuel Processing for Fuel Cells to Fuel Synthesis from Hydrogen and Carbon Dioxide
Aug 2023
Publication
Improving the energy efficiency of existing technologies such as the on-board power supply of trucks ships and aircraft is an important endeavor for reducing primary energy consumption. The approach consists of using fuel cell technology in conjunction with hydrogen production from liquid fuels. However the energy transition with the goal of complete climate-neutrality requires technological changes in the use of hydrogen produced from renewable energy via electrolysis. Synthetic fuels are an important building block for drive systems that will continue to require liquid energy carriers in the future due to their range. This study addresses the question of whether technical devices that were developed for the generation of hydrogen from liquid fuels for fuel cells to generate electricity are now suitable for the reverse process chain or can play an important role in it. The new process chain produces hydrogen from sustainable electricity combining it with carbon dioxide to create a synthetic liquid fuel.
H2-powered Aviation at Airports – Design and Economics of LH2 Refueling Systems
Feb 2022
Publication
In this paper the broader perspective of green hydrogen (H2) supply and refueling systems for aircraft is provided as an enabling technology brick for more climate friendly H2-powered aviation. For this two H2 demand scenarios at exemplary airports are determined for 2050. Then general requirements for liquid hydrogen (LH2) refueling setups in an airport environment are derived and techno-economic models for LH2 storage liquefaction and transportation to the aircraft are designed. Finally a cost tradeoff study is undertaken for the design of the LH2 setup including LH2 refueling trucks and a LH2 pipeline and hydrant system. It is found that for airports with less than 125 ktLH2 annual demand a LH2 refueling truck setup is the more economic choice. At airports with higher annual LH2 demands a LH2 pipeline & hydrant system can lead to slight cost reductions and enable safer and faster refueling. However in all demand scenarios the refueling system costs only mark 3 to 4% of the total supply costs of LH2. The latter are dominated by the costs for green H2 produced offsite followed by the costs for liquefaction of H2 at an airport. While cost reducing scaling effects are likely to be achieved for H2 liquefaction plants other component capacities would already be designed at maximum capacities for medium-sized airports. Furthermore with annual LH2 demands of 100 ktLH2 and more medium and larger airports could take a special H2 hub role by 2050 dominating regional H2 consumption. Finally technology demonstrators are required to reduce uncertainty around major techno-economic parameters such as the investment costs for LH2 pipeline & hydrant systems.
Experimental Study of Cycle-by-cycle Variations in a Spark Ignition Internal Combustion Engine Fueled with Hydrogen
Feb 2024
Publication
High fluctuations in the combustion process from one cycle to another referred to as cycle-by-cycle variations can have adverse effects on internal combustion engine performances particularly in spark ignition (SI) engines. These effects encompass incomplete combustion the potential for misfires and adverse impacts on fuel economy. Furthermore the cycle-by-cycle variations can also affect a vehicle’s drivability and overall comfort especially when operating under lean-burn conditions. Although many cycle-by-cycle analyses have been investigated extensively in the past there is limited in-depth knowledge available regarding the causes of cycle-by-cycle (CbC) variations in hydrogen lean-burn SI engines. Trying to contribute to this topic the current study presents a comprehensive analysis of the CbC variations based on the cylinder pressure data. The study was carried out employing a hydrogen single-cylinder research SI engine. The experiments were performed by varying more than fifty operating conditions including the variations in lambda spark advance boost pressure and exhaust gas recirculation however the load and speed were kept constant throughout the experimental campaign. The results indicate that pressure exhibits significant variations during the combustion process and minor variations during non-combustion processes. In the period from the inlet valve close till the start of combustion pressure exhibits the least variations. The coefficient of variation of pressure (COVP) curve depicts three important points in H2-ICE as well: global minima global maxima and second local minima. The magnitude of the COVP curve changes across all the operating conditions however the shape of the COVP curve remains unchanged across all the operating conditions indicating its independence from the operating condition in an H2-ICE. This study presents an alternative approach for a quick combustion analysis of hydrogen engines. Without the need for more complex methodologies like heat release rate analysis the presented cylinder pressure cycle-by-cycle analysis enables a quick and precise identification of primary combustion features (start of combustion center of combustion end of combustion and operation condition stability). Additionally the engine control unit could implement these procedures to automatically adjust cycle-by-cycle variations therefore increasing engine efficiency.
Parameterization Proposal to Determine the Feasibility of Geographic Areas for the Green Hydrogen Industry under Socio-environmental and Technical Constraints in Chile
Oct 2023
Publication
Chile abundant in solar and wind energy resources presents significant potential for the production of green hydrogen a promising renewable energy vector. However realizing this potential requires an understanding of the most suitable locations for the installation of green hydrogen industries. This study proposes a quantitative methodology that identifies and ranks potential public lands for industrial use based on a range of technical parameters (such as solar and wind availability) and socio-environmental considerations (including land use restrictions and population density). The results reveal optimal locations that can facilitate informed sustainable decision-making for large-scale green hydrogen implementation in Chile. While this methodology does not replace project-specific technical or environmental impact studies it provides a flexible general classification to guide initial site selection. Notably this approach can be applied to other regions worldwide with abundant solar and wind resources such as Australia and Northern Africa promoting more effective and sustainable global decision-making for green hydrogen production.
Global Hydrogen and Synfuel Exchanges in an Emission-Free Energy System
Apr 2023
Publication
This study investigates the global allocation of hydrogen and synfuels in order to achieve the well below 2 ◦C preferably 1.5 ◦C target set in the Paris Agreement. For this purpose TIMES Integrated Assessment Model (TIAM) a global energy system model is used. In order to investigate global hydrogen and synfuel flows cost potential curves are aggregated and implemented into TIAM as well as demand technologies for the end use sectors. Furthermore hydrogen and synfuel trades are established using liquid hydrogen transport (LH2 ) and both new and existing technologies for synfuels are implemented. To represent a wide range of possible future events four different scenarios are considered with different characteristics of climate and security of supply policies. The results show that in the case of climate policy the renewable energies need tremendous expansion. The final energy consumption is shifting towards the direct use of electricity while certain demand technologies (e.g. aviation and international shipping) require hydrogen and synfuels for full decarbonization. Due to different security of supply policies the global allocation of hydrogen and synfuel production and exports is shifting while the 1.5 ◦C target remains feasible in the different climate policy scenarios. Considering climate policy Middle East Asia is the preferred region for hydrogen export. For synfuel production several regions are competitive including Middle East Asia Mexico Africa South America and Australia. In the case of security of supply policies Middle East Asia is sharing the export volume with Africa while only minor changes can be seen in the synfuel supply.
Can an Energy Only Market Enable Resource Adequacy in a Decarbonized Power System? A Co-simulation with Two Agent-based-models
Feb 2024
Publication
Future power systems in which generation will come almost entirely from variable Renewable Energy Sources (vRES) will be characterized by weather-driven supply and flexible demand. In a simulation of the future Dutch power system we analyze whether there are sufficient incentives for market-driven investors to provide a sufficient level of security of supply considering the profit-seeking and myopic behavior of investors. We cosimulate two agent-based models (ABM) one for generation expansion and one for the operational time scale. The results suggest that in a system with a high share of vRES and flexibility prices will be set predominantly by the demand’s willingness to pay particularly by the opportunity cost of flexible hydrogen electrolyzers. The demand for electric heating could double the price of electricity in winter compared to summer and in years with low vRES could cause shortages. Simulations with stochastic weather profiles increase the year-to-year variability of cost recovery by more than threefold and the year-to-year price variability by more than tenfold compared to a scenario with no weather uncertainty. Dispatchable technologies have the most volatile annual returns due to high scarcity rents during years of low vRES production and diminished returns during years with high vRES production. We conclude that in a highly renewable EOM investors would not have sufficient incentives to ensure the reliability of the system. If they invested in such a way to ensure that demand could be met in a year with the lowest vRES yield they would not recover their fixed costs in the majority of years.
The Potential Role of a Hydrogen Network in Europe
Jul 2023
Publication
Europe’s electricity transmission expansion suffers many delays despite its significance for integrating renewable electricity. A hydrogen network reusing the existing gas network could not only help to supply the demand for low-emission fuels but could also balance variations in wind and solar energies across the continent and thus avoid power grid expansion. Our investigation varies the allowed expansion of electricity and hydrogen grids in net-zero CO2 scenarios for a sector-coupled European energy system capturing transmission bottlenecks renewable supply and demand variability and pipeline retrofitting and geological storage potentials. We find that a hydrogen network connecting regions with low-cost and abundant renewable potentials to demand centers electrofuel production and cavern storage sites reduces system costs by up to 26 bnV/a (3.4%). Although expanding both networks together can achieve the largest cost reductions by 9.9% the expansion of neither is essential for a net-zero system as long as higher costs can be accepted and flexibility options allow managing transmission bottlenecks.
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