Reversible solid oxide electrochemical system as seasonal energy storage in ultra-high renewable energy grid scenarios

Abstract

The electrochemical production of hydrogen by surplus variable renewable energy (VRE) can reduce the cost of future energy systems. Supported by favorable electric grid conditions and increasing research and development investments, large-scale power-to-gas (P2G) plants are increasingly being deployed worldwide. Techno-economic and energy planning analyses involving hydrogen production and energy storage typically take either "price-taker" or "production cost" modeling approaches, with the "price-taker" approach being predominant. However, given the increasing development and deployment of P2G plants, price-taker models based on the fundamental assumption that the presence of an individual P2G plant will not affect electric grid conditions are no longer valid. To address this issue, the present research uses a production cost model that minimizes the electric grid's total energy generation cost to capture the benefits of operating a utility-scale, grid-connected reversible electrolyzer plant. A generic methodology to analyze seasonal energy storage operating in an ultra-high VRE grid (> 90% integration levels) is developed, and a newly developed seasonal storage modeling methodology is then implemented to analyze the integration of a reversible solid-oxide electrolyzer system with such highly penetrated VRE grid scenarios. This research shows that the reversible solid-oxide system operating in an ultra-high VRE grid can reduce the annual electricity generation cost by 5-15% (subject to grid conditions).