Thermal energy storage and power-to-heat in France

The French Environment and Energy Management Agency (ADEME, Agence de l’Environnement et de la Maitrise de L’Energie), the French technical organisation for energy (ATEE, Association Technique Energie Environnement) and 10 industrials commissioned Enea Consulting, Artelys and the French geological survey (BRGM, Bureau de Recherches Géologiques et Minières) to conduct a study on the value of thermal energy storage and power-to-heat in France.

Heat accounts for around half of France’s energy consumption and is a great lever for reducing carbon emissions through renewable energy and waste heat recovery. France is strongly committed to the energy transition with ambitious targets, notably by reducing primary energy consumption and an increasing the share of renewables and waste energy recovery. Thermal energy storage and power-to-heat are two promising solutions to be analysed in order to assess their potential to help decarbonise the French thermal mix.

This study outlined the landscape of technical solutions already available or under development for the thermal energy storage and power-to-heat sectors. It assessed the value of these technologies and their techno-economic potential for a number of case studies in applications and sectors deemed of interest, [including district heating, industrial waste heat recovery, combined heat and power, domestic hot water.

Thermal energy storage and power-to-heat to support the increase of renewable heat supplied by district heating grids

The study shows that when a grid operator faces gradual increase in heat demand, thermal energy storage brings value in postponing a heavy investment in upgrading the grid. Besides, thermal energy storage provides flexibility services and more in heat supply to the end-users. It also helps optimise the operation of biomass boilers.

Heat pumps are an interesting option and can be economically viable to supply renewable heat to district heating grids for base and semi-base load. Thermal energy storage guarantees and optimises the performance of heat pumps. However, arbitrage on grid electricity prices with heat pumps has limited value if intraday spreads are not significant.

In general, the value of heat storage and power-to-heat solutions and their potential for district heating applications strongly relies on temperature levels in those grids.

Thermal energy storage to use industrial waste heat

Thermal energy storage can help use waste heat from batch processes that would otherwise not be suited to serve a steady heat demand. The study highlights that for some profiles of industrial waste heat, these kinds of projects are already profitable.

Beyond current niche opportunities, the deployment of waste heat recovery projects with thermal storage in the industry still require support mechanisms such as feed-in tariffs for waste heat and financing solutions with access to capital at a reduced cost.

Thermal energy storage at domestic scale and flexibility of the electricity grid at national scale

Water heaters with integrated storage of hot water are massively used in France and are a critical energy storage asset for the electricity grid operator. The uptake of domestic heat-pumps with a higher energy efficiency and longer periods of heating than conventional water heaters might impact the situation. However, the study shows that a massive uptake of domestic heat pumps as water heaters would not impose significant constraints on the management of the grid.