The Role Of Repurposing Coal Plants to Thermal Energy Storage in the Context of India

Abstract

Substantial coal phase out initiatives have been growing as the world mobilizes to meet the Paris climate goals. However, the stranded asset risk associated with this critical transition could fall disproportionately on Asian economies with younger coal fleets, like India. Here, we use a bottom-up and top-down techno-economic modeling approach to explore the value of installing commercially available, molten-salt thermal energy storage (TES) systems for repurposing existing coal power plants in the Indian context. We combine thermodynamic simulation and an economic optimization model to evaluate design and operations of TES systems for a variety of technology assumptions, coal plant archetypes, and electricity price scenarios. Key drivers of economic viability identified include longer remaining plant lifetime, increasing peak TES temperature, lower TES energy capacity cost, co-production of waste heat for end-uses, and increasing temporal variability of electricity prices. The plant-level analysis was then extended to screen for the potential for TES retrofits for the coal power fleet in Uttar Pradesh, the most populous Indian state with amongst the largest coal capacity. Analysis for a single electricity price scenario indicates that over 89% of the coal capacity in the state can be retrofitted and recover the costs of TES retrofits. Under the top-down, capacity expansion modeling approach, we find TES retrofits can save 3-6% in system costs in zero emission scenarios and operate as long-duration energy storage, complementing shorter-duration Li-ion based energy storage. Our results justify further investigation into articulating the value of repurposing coal plants from the interests and positions of different just energy transition stakeholders.