Evaluating Power-to-Heat-to-Power Storage Potential in Wind- and Solar-Dominated Energy Markets

TL;DR

This paper evaluates the potential of Power-to-Heat-to-Power Storage systems in wind- and solar-dominated regions, highlighting their viability in specific heating configurations and the importance of cost and efficiency factors.

Contribution

It provides a comparative analysis of PHPS systems in different regional energy contexts using open-source modeling, emphasizing conditions for their competitiveness.

Findings

PHPS is most viable in wind-dominated regions and individual heating systems.

Waste heat recovery significantly improves PHPS competitiveness.

PHPS is less competitive in district heating systems due to centralized storage preferences.

Abstract

This study assesses the role of Power-to-Heat-to-Power Storage (PHPS) systems, also known as Carnot batteries, in the national energy system of a wind-dominated (Denmark) and a solar-dominated (Spain) region. Using the open-source PyPSA framework, we model sector-coupled electricity and heating systems, and evaluate individual and district heating configurations for heat provision at residential level, with and without PHPS waste heat recovery. Our results show that PHPS is most viable in individual heating systems, and in wind-dominated locations, where its low cost per energy capacity enables it to balance long-duration fluctuations. Moreover, waste heat recovery is essential to enhance PHPS competitiveness, allowing it to displace lithium-ion batteries. Conversely, PHPS is largely outcompeted in district heating systems, which favour low-cost centralized energy storage. Sensitivity analysis highlights that PHPS viability depends primarily on achieving low energy capacity costs and maintaining reasonable heat-to-power conversion efficiencies. Overall, while PHPS complements existing storage technologies by providing dispatchable electricity and heat, its potential adoption is highly context-dependent, influenced by climate, heating system configuration, and competing storage costs.