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Due to its ability to perform clean, efficient processes, hydrogen has long been promoted as the energy carrier of the future, but recent activity and advances suggest a tipping point has been reached as hydrogen is now being recognized by much of the world for its unique capabilities to strongly support global efforts in achieving climate neutrality. The coming decades will require a massive increase in the amount of hydrogen used in the energy system as well as a transition from largely thermochemical to predominantly electrochemical processes involving hydrogen. For this to happen, hydrogen will need to globally approach the gigaton-scale on an annual basis. Thus, before hydrogen can fully achieve its potential, challenges that need to be addressed include achieving scale and further research and development (R&D) advances.

The production of energy carriers based on renewable electricity via the Power-to-X (PtX) approach holds the key for a holistic transformation of our global industries from fossil fuels towards renewable energy sources. To compete with cheap fossils, PtX products demand energy-efficient processes and low-cost renewable electricity. Therefore, the import of PtX products from countries with high renewable energy potentials to countries with high energy demand presents a promising pathway. However, the question which set of PtX products qualifies as suitable for long-distance transport has not yet been answered. In this context, this paper assesses the energy and cost efficiency of five PtX energy carriers (methane, methanol, ammonia, liquefied hydrogen and hydrogen bound in LOHC). Furthermore, we evaluate the influence of fluctuating renewables, availability of water and transport distance in a case study for large-scale PtX production in Morocco. Our results show that the evaluated PtX pathway efficiencies vary between 40–52% (base cases) and 44–58% (optimistic cases). None of the pathways assessed is significantly affected in its overall efficiency by a ship transport over an exemplary distance of 4000 km. However, for longer transport distances the cost difference between the assessed pathways increases. The production cost of the PtX energy carriers (124–156 € per MWh) depends on the availability of excess heat, energy density of the product and, if required, liquefaction efforts. In summary, the paper reveals that the long-distance transport and import of PtX products present an interesting option for the ongoing integration of renewable electricity into our energy system and industries. The petrochemical and steel industries in particular, as well as heavy goods transport, shipping and aviation, will be highly dependent on these imported synthetic energy sources.

The utilization of hydrogen and hydrogen-based fuels is a promising option to reduce greenhouse gas emissions of heavy-duty vehicles. Here, the production of sustainable hydrogen plays a key role. Very promising is the production of hydrogen by means of water electrolysis that links fluctuating electricity production from renewable sources with sectors based on chemical energy carriers. Water electrolysis will be one of the key technologies to reduce the energy system transformation costs and to stabilize the electricity grid. Hydrogen can be used directly as a fuel in heavy-duty vehicles or converted with CO2 to fuels like methanol or Fischer-Tropsch products. Methanol can be used both as a fuel and as feedstock for further upgrading to fuels like dimethyl ether (DME), oxymethylene ether (OME), methanol-to-gasoline (MtG) and methanol-to-jet fuel. Recently, also the conversion of hydrogen with nitrogen to ammonia as fuel gains increasing interest in combustion engines. Beyond CO2 reduction exhaust gas emissions have also to be reduced significantly. CatVap® is an innovative fuel processing technology that enables efficient exhaust gas treatment in order to achieve near-zero emission mobility. In addition, hydrogen can be used to operate fuel cell power trains, which is more and more discussed for heay-duty applications. Now it’s the time for a broader market introduction of hydrogen and hydrogen-based fuels in the mobility sector and thus, for cost reduction due the corresponding scale-effects.

Dimethyl ether (DME) is a power-to-liquids product with interesting key characteristics and a broad spectrum of applications as a green fuel, as a compound for the chemical industry and as a chemical building block. At present, DME is produced from fossil resources like natural gas and coal. The shift to renewable production from CO2 and hydrogen will allow emerging pathways for the production of DME to find its way to the market. State-of-the-art and emerging DME production pathways are presented in detail. Particular focus is hereby put on the influence of a renewable production based on CO2 and hydrogen. Last but not least, economic insights into a power-to-DME process are given in the last chapter.

Oxymethylene Dimethyl Ethers (OMEs) are promising diesel fuel alternatives and interesting solvents for various industrial applications. In this report, a well-to-wheel life cycle assessment of short OME oligomers as produced via a Power-to-Liquid (PtL) pathway has been conducted. Variations in electricity and carbon dioxide supply as well as the hardware demand for the PtL plant components (e.g. PEM water electrolysis, carbon capturing, and 36 kta OME plant capacity) have been considered. Conventional diesel fuel is used as the comparative benchmark. In scenarios with a high share of renewable electricity well-to-wheel greenhouse gas emission for OME3–5 fuel is advantageous compared to fossil diesel. For the best case, well-to-wheel greenhouse gas emissions can be reduced by 86%, corresponding to 29 g(CO2eq) km−1 (OME3–5-fuel) compared to 209 g(CO2eq) km−1 (diesel fuel). However, these results are highly sensitive to the applied method with regard to system multifunctionality. A sensitivity analysis indicates that input electricity at ∼50 g(CO2eq) kWhel−1 enables well-to-wheel greenhouse gas emissions of

The synthesis of sustainable methanol based on renewable electricity generation, sustainable hydrogen (H2) and recycled carbon dioxide (CO2) represents an interesting sustainable solution to integrated renewable energy storage and platform chemical production. However, the business case for this electricity based product (denoted hereafter as eMeOH) under current market conditions (e.g. vs. conventional fossil methanol (fMeOH) production cost) and the appropriate implementation scenarios to increase platform attractiveness and adoption have to be highlighted. The aim of the following study was to perform a dynamic simulation and calculation of the cost of eMeOH production (where electricity is generated at a wind park in Germany), with comparison made to grid connected scenarios. Consideration of these scenarios is made with particular respect to the German energy market and potential for the reduction in fees/taxes (i.e. for electrolyser systems). This evaluation and indeed the results can be viewed in light of European Union efforts to support the implementation of such technologies. In this context, CO2 is sourced from EU relevant sources, namely a biogas or ammonia plant, the latter profiting from the resulting credit arising from CO2 certificate trading. Variation in electricity cost and the CO2 certificate price (in the presented sensitivity study) demonstrate a high cost reduction potential. Under the energy market conditions of Germany it is found that eMeOH production costs vary between €608 and 1453 per tonne based on a purely grid driven scenario, whilst a purely wind park supplied scenario results in €1028–1067 per tonne. The reported results indicate that the eMeOH production cost in Germany is still above the present (although variable) market price, with the economical evaluation indicating that electrolyser and H2 storage represent the lion share of investment and operational cost. Substitution of fMeOH results in CO2 avoidance costs between €365 and 430 per tonne of CO2eq avoided for green methanol produced in Germany. The presented assessment indicates that the eMeOH production cost in Germany will reach market parity in ca. 2030–2035 with the price for the avoidance of CO2eq turning from a cost to a benefit at around the same time. Optimistically, the cost is predominantly influenced by rapidly reducing renewable electricity costs as is already the case in South American and Arabic countries offering the potential for methanol production at a cost of

Sektorenkopplung | Der Umbau der Energiesysteme ist in vollem Gange – hierzulande und weltweit. Immer mehr fossile Kraftwerke werden abgeschaltet, Windenergie- und Photovoltaikanlagen sind auf dem Vormarsch. Der wachsende Anteil des erneuerbaren Stroms muss jedoch in Einklang mit dem Bedarf gebracht werden. Künftig wird daher eine Stärkung der vierten Säule des Energiesystems nötig: Neben Erzeugung, Transport und Verbrauch treten Speichertechnologien. Große Vorteile bietet hier der chemische Energieträger Wasserstoff – er ist flexibel herstell- und einsetzbar und kann große Anteile erneuerbarer Energien auch in die Sektoren Mobilität, Wärme und Industrie bringen. Ein aktueller Blick auf Technologie, Potenziale und die rasante internationale Entwicklung.

Oxymethylene Dimethyl Ethers (OME) are promising diesel fuel alternatives and interesting solvents for various industrial applications. In this report (Reproduced from [Hank et al. 2019] with permission from the Royal Society of Chemistry), a well-to-wheel Life Cycle Assessment of short OME oligomers as produced via a Power-to-Liquid (PtL) pathway has been conducted. Variations in electricity and carbon dioxide supply as well as the hardware demand for the PtL plant components (e.g. PEM water electrolysis, carbon capturing, 36 kta OME plant capacity) have been considered. Conventional diesel fuel is used as the comparative benchmark.

The manufactures of internal combustion engines face currently a lot of challenges. Among these are the required drastic emission reductions of carbon dioxide (CO2) as well as harmful substances the most prominent. As a consequence of these harsh market conditions solutions that could cope with this framework are urgently needed. In this context the state of the art of synthetic fuels as an essential part of the energy system is discussed and how they could offer solutions.

Methanol synthesis based on renewable electricity generation, sustainable hydrogen (H2) and recycled industrial carbon dioxide (CO2) represents an interesting solution to integrated renewable energy storage and platform chemical production. In this work the technological overview of the methanol synthesis from conventional feedstocks and based on CO2 is provided. The business case for this electricity based product under current market conditions (e.g. vs. conventional fossil methanol production cost) and the appropriate implementation scenarios to increase methanol attractiveness and adoption is highlighted. A complementary ecological evaluation of PtM process is provided and recommendations for this sustainable platform based on these understandings are highlighted.

Electrochemical impedance spectroscopy is used during operation of different polymer electrolyte membrane fuel cell (PEMFC) stack assemblies at various conditions with special interest given to the characteristic time constant tlow-f derived from the low-frequency arc of the spectra which is typically in the range of approximately 15-0.5 Hz. This was done by fitting an equivalent electrical circuit (EEC) consisting of one resistor and two RC-elements to the data. Parameter variation performed on a 90-cell stack assembly suggests that conditions leading to different air flow velocities in the flow channels affect tlow-f while other parameters like humidity influence the impedance spectrum, but not tlow-f. Comparison of the stoichiometry variation between short stack and locally resolved single cell shows similar results with the stack's time constant matching that of the cell's segments which are located off-center toward the outlet. However, a nonlinear dependency between gas flow velocity and tlow-f especially at low stoichiometric values is obvious. Results from stoichiometry variations at different pressure levels suggest that this could be attributed to the different steady-state oxygen partial pressures during the experiments. Comparison of the stoichiometry variation between different stack platforms result in similar dependencies of tlow-f on air flow rate with respect to a reference oxygen partial pressure regardless of size, flow field, geometry, or cell count of the stack. The time constant caused by oxygen diffusion through the gas diffusion layer (GDL), tGDL, was approximated and compared to tlow-f. While it was found that tlow-f ≫ tGDL at low stoichiometric values, tlow-f decreases toward tGDL at very high gas flow rates, suggesting that tGDL offsets tlow-f and becomes dominating if no oxygen concentration variation along the flow channel was present.

The transformation of energy systems towards high shares of renewable energy production while phasing out the use of fossile carbon-based energy carriers requires both a highly resilient energy system and an energy carrier which couples the electricity sector with energy consuming sectors like transportation, industry and chemistry. This is why we now see the advent of large-scale water electrolyzers for the production of sustainable hydrogen. Hydrogen will be an important feedstock for fuel cell cars, busses, trucks and trains, but also an important basic chemical for refineries, for the steel production and for various kinds of sustainable chemicals like fertilizers or polymers. This talk will adress the status quo of electrolyzer technologies and techno-economic analyses of power-to-hydrogen plants with high shares of intermittent power supply. The whole value chain from sustainable power generation to the production of liquid energy carriers will be described. An overview of the research activities of the Fraunhofer institute for Solar Energy Systems (ISE) for the realization of an integrated and sustainable energy system will be given as well. Figure 1

The United Nations Framework Convention on Climate Change (COP21) in Paris last year has underlined the urgency of a fast and consequent transformation of the various energy systems from a fossil based energy feedstock towards renewable energies like photovoltaics, wind- and hydropower, in order to drastically decrease the greenhouse gas emissions (GHG). Such a transformation requires a thorough restructuring of the energy systems with all energy carriers and consumer sectors including its intersectoral dependencies, grid structures and energy storage needs. At Fraunhofer ISE we performed time-resolved studies on how to reach the main goal of the German energy transformation to decrease its GHG emissions by at least 80% until 2050 and thus, to widely decarbonize all energy related sectors. Potential transformation pathways based on various scenarios were studied and the required costs were modelled for each scenario. The results of this modelling made very obvious that the ambitious GHG reduction targets can only be fulfilled by a strong rise in electricity generation by fluctuating renewable energies and on the other hand by the installation of large plants for producing synthetic energy carriers from renewable energies. The most versatile energy carrier for such large amounts of energy is hydrogen produced from water electrolysis. Hydrogen can be stored in large amounts in gas tube fields or salt caverns and can be used directly either in fuel cell cars and buses as a fuel or in stationary combined heat and power fuel cell systems. Furthermore the hydrogen can be used in order to hydrogenate CO2 and thus to generate green liquid fuels such as oxymehylenether (OME) or other chemicals in order to replace oil based products. The conversion of electricity into hydrogen is called Power-to-Gas, the further processing of the hydrogen and CO2 towards liquid energy carriers and chemicals is called Power-to-Liquid. With the advent of various Power-to-Gas demonstration projects it becomes clear how important this technology will be in the future energy system. Distributed water electrolyzers in the Megawatt power range will stabilize the grid frequency and voltage or will deliver other ancillary services and thus, will contribute to the secondary balancing market. Alkaline water electrolyzers are applied for more than 100 years in industrial applications and are nowadays complemented by proton exchange membrane (PEM) electrolysers in order to cover the needs for a highly dynamic load in the grid. However, main challenges of the PEM technology are high costs associated with expensive materials and the durability of cells and stacks. With ongoing technological development it is expected that PEM electrolysis systems become a competitive alternative to alkaline systems in the next years. In this talk, the technological base of water electrolyzers will be described and the related performance data, life-time expectation and cost reduction potential will be discussed. Furthermore the impact of distributed water electrolyzers in the Megawatt power range as part of an increasingly renewable energy system in terms of Power-to-Gas modelling scenarios will be given. Figure 1