The European Commission is considering electrolysis as a high priority for the development of a hydrogen-integrated European energy system, and a cornerstone in the European Hydrogen Strategy [1], where it is planned to deploy electrolyzers en masse on the market: 6 GW within 2024 and another 40 GW within 2030. Several technologies will be competing here, the highest maturity being occupied by water electrolysis such as alkaline electrolysis (AEL) and proton-conductive membrane electrolysis (PEMEL). A considerable slice of the market is being shared by steam electrolysis, which is rapidly maturing, scaling up and looking to be competitive in the short term against the low-temperature technologies, particularly in target sectors. Steam electrolysis, also known as high-temperature electrolysis, comprises several technologies, some more advanced in development, others still at the research level. They are a central part of the European Partnership of Hydrogen, receiving a large contribution within the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) in Horizon 2020. They will be part of the program of the next European Partnership on Hydrogen, Clean Hydrogen for Europe, and should reach the same maturity level as AEL and PEMEL. Among other technologies proton-conductive ceramic electrolyzers (PCCEL) are well worth mentioning and are analyzed in this chapter. This technology holds high potential, meeting the challenge of operating at lower temperatures than solid oxide electrolyzers (SOEL) and integrating additional functions such as purification, filtration, separation, and/or compression of hydrogen. Both SOEL and PCCEL are technologies able to operate at medium-high temperatures, their advantages being management of the conversion process, capacity to capture external waste heat for the production of steam, and their cell structure making limited use of critical raw materials. The most mature technology is solid oxide cells, already available as demo technologies, and soon to be scaled up to reach market maturity and commercial application in several sectors, as presented in Section 5.2. A second technology, proton-conductive ceramic (PCC) cells, is still at the research stage and needing to consolidate the cell layout, specific geometry, materials utilized, and optimal working conditions. Major studies on SOEL started to appear back in the 1970s [2-5]. However, interest in the technology rose in the 1980s, prompting many research projects. Among these studies one should note the investigations performed by Westinghouse [6-7], the research by Barbi and Mari [8-12], and the HOTTELLY project described by Dönitz et al. [13-16]. The discovery of PCC is attributed to Professor Hirosyasu Iwahara in the late 1970s; investigation of these materials for electrolysis applications started right from the beginning of the 1980s [17]. In the following years, PCCEL acquired increasing interest and more details on materials and applications of this technology will be presented in what follows. This chapter will present an analysis of the basic principles of hightemperature electrolysis and related technologies, with a specific focus on SOEL and PCCEL cells and structures, including the main materials, as well as an overview of the main applications they can support with their different technology configurations and systems, and the future prospects for development as breakthrough applications.
High-temperature electrolysis: efficient and versatile solution for multiple applications
Luigi Crema;Matteo Testi;Martina Trini
2021-01-01
Abstract
The European Commission is considering electrolysis as a high priority for the development of a hydrogen-integrated European energy system, and a cornerstone in the European Hydrogen Strategy [1], where it is planned to deploy electrolyzers en masse on the market: 6 GW within 2024 and another 40 GW within 2030. Several technologies will be competing here, the highest maturity being occupied by water electrolysis such as alkaline electrolysis (AEL) and proton-conductive membrane electrolysis (PEMEL). A considerable slice of the market is being shared by steam electrolysis, which is rapidly maturing, scaling up and looking to be competitive in the short term against the low-temperature technologies, particularly in target sectors. Steam electrolysis, also known as high-temperature electrolysis, comprises several technologies, some more advanced in development, others still at the research level. They are a central part of the European Partnership of Hydrogen, receiving a large contribution within the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) in Horizon 2020. They will be part of the program of the next European Partnership on Hydrogen, Clean Hydrogen for Europe, and should reach the same maturity level as AEL and PEMEL. Among other technologies proton-conductive ceramic electrolyzers (PCCEL) are well worth mentioning and are analyzed in this chapter. This technology holds high potential, meeting the challenge of operating at lower temperatures than solid oxide electrolyzers (SOEL) and integrating additional functions such as purification, filtration, separation, and/or compression of hydrogen. Both SOEL and PCCEL are technologies able to operate at medium-high temperatures, their advantages being management of the conversion process, capacity to capture external waste heat for the production of steam, and their cell structure making limited use of critical raw materials. The most mature technology is solid oxide cells, already available as demo technologies, and soon to be scaled up to reach market maturity and commercial application in several sectors, as presented in Section 5.2. A second technology, proton-conductive ceramic (PCC) cells, is still at the research stage and needing to consolidate the cell layout, specific geometry, materials utilized, and optimal working conditions. Major studies on SOEL started to appear back in the 1970s [2-5]. However, interest in the technology rose in the 1980s, prompting many research projects. Among these studies one should note the investigations performed by Westinghouse [6-7], the research by Barbi and Mari [8-12], and the HOTTELLY project described by Dönitz et al. [13-16]. The discovery of PCC is attributed to Professor Hirosyasu Iwahara in the late 1970s; investigation of these materials for electrolysis applications started right from the beginning of the 1980s [17]. In the following years, PCCEL acquired increasing interest and more details on materials and applications of this technology will be presented in what follows. This chapter will present an analysis of the basic principles of hightemperature electrolysis and related technologies, with a specific focus on SOEL and PCCEL cells and structures, including the main materials, as well as an overview of the main applications they can support with their different technology configurations and systems, and the future prospects for development as breakthrough applications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
