The increasing share of renewable electricity generation in our energy systems leads to a variable and intermittent energy production, which requires large scale, cost-effective storage systems:

• to balance out the resulting mismatch between generation and demand, and
• to provide flexibility in order to strengthen the resilience of the electricity grid and ensure a stable energy supply.

In this context, Carnot Batteries have the potential to provide large-scale storage in a more costeffective and environmentally friendly way than conventional batteries, using benign materials such as water, rocks, sand or molten salts. In Task 36 – Carnot Batteries, possible designs of such a Carnot Battery have been collected, classified and potential use cases & barriers have been discussed.

The energy transition however goes beyond the electricity sector. The heating sector as well needs to be decarbonised, to a large extent through the electrification of the heating supply using e.g. electroboilers, electric heaters and heat pumps.

This additional electricity demand presents a significant challenge for our electricity grid. At the same time, the flexible coupling of both the electricity and heating sector using thermal storage solutions provides an enormous change to simultaneously achieve cost-effective storage and the abovementioned flexibility in the electricity sector, as well as a decarbonization of the heating sector.

Key Technologies that support such a cost-effective and flexible – thermal storage based – sector coupling are:

• Heat integrated Carnot Batteries resp. Carnot Battery solutions in which the options to integrate heat during charging and extract heat during discharging are fully exploited.
• Thermal storage supported power-to-heat solutions.

The overarching goal of this Task is to support the energy transition – of the fossil fuels-based energy system – towards a zero-carbon energy system, through the deep understanding and assessment of the use cases of storage supported Power-to-Heat technologies and heat integrated Carnot batteries. Therefore, this Task aims to establish and maintain a platform to bring together experts from government agencies, industry and academia to:

• identify and evaluate the role of storage supported Power-to-Heat and heat-integrated Carnot batteries in the energy transition, and
• strengthen the international visibility of these solutions, and create a common understanding of their potential in industry and policy.