Techno-economic analyses of hydrogen-based systems for energy conversion and storage

Abstract

Hydrogen (H₂) is both a promising energy carrier, with its high energy content of 141 MJ/kg, and a key industrial commodity used in the chemical, steel, fertilizer, and refining industries. Currently, H₂ production is mostly achieved through steam methane reforming (SMR) and coal gasification, which are highly polluting processes. With the urgent need for global decarbonization, alternative H₂ production methods are emerging, including membraneless electrolyzers (MEs) and reversible protonic ceramic cells (RePCCs). MEs eliminate the need for the expensive and delicate membranes required in conventional electrolysis processes, instead achieving hydrogen separation from other product gases through fluid-dynamic forces. Reversible cells, on the other hand, can both generate hydrogen and consume it to produce electricity in energy storage systems, leaving water as the only waste product.

RePCCs and MEs could play an important role in the transition to a sustainable economy and therefore, this work performs a techno-economic analysis of these technologies to assess their commercial viability. The techno-economic analysis of MEs was originally part of a previous thesis but was further developed and refined during this MPhil to achieve a comprehensive cost estimation. Furthermore, a complete overview of ME technology was performed to evaluate the most promising designs and applications, covering the production of H₂ and other chemicals.

The core part of this thesis presents a complete economic assessment of RePCCs, using the refined techno-economic framework for MEs as starting point. RePCCs are a recently developed technology that could be well suited to energy storage applications. These cells can operate at lower temperatures (500-600 °C) compared to conventional solid-oxide fuel cells (800 °C), reducing their associated operational and maintenance costs. A manufacturing cost model for RePCCs was developed and the levelized cost of storage (LCOS) of systems based on RePCCs was evaluated. LCOSs up to ~1.5 USD/kWh were obtained for RePCCs in seasonal energy storage (lower costs were obtained for progressively shorter storage times), considerable smaller than the ~5.5 USD/kWh of Li-ion batteries. These results demonstrate that RePCCs can be more cost-effective than Li-ion batteries for medium to long-term energy storage. The results of this study provide important evidence of the efficacy of these H₂ conversion technologies, which can guide future research and policy directions.

Date of Award	2023
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Francesco CIUCCI (Supervisor)