Material Insights · Understanding the Material World

Thermochemical storage: Impact and additionality

The seasonal prize: summer sun replacing winter gas

What this tab covers The impact and additionality lens: what it displaces on the grid, who gains and who bears the burden along the supply chain, and what happens at end of life.

If it works, thermochemical storage could shift summer heat to winter and supply high-temperature heat from renewables, with a small life-cycle footprint. Impact today is negligible because deployment is minimal.

Grid decarbonisation versus fossil displacement

Mixed

The long-term prize is seasonal: storing summer solar heat to displace winter gas boilers, which no battery can do cheaply, and supplying round-the-clock solar power. A life-cycle study of calcium looping found about 24 kg CO2e per MWh for a solar plant with this storage, against 40 kg for molten salt plants, with energy payback of 2.2 years for daily storage and 2.5 years for seasonal storage. Today the displacement is close to zero.9

Life-cycle emissions, CSP with calcium looping vs molten salt 24 vs 40 kg CO2e per MWh9 Energy payback, calcium looping plant 2.2-2.5 years9

Just transition and local community impact

Mixed

Activity is concentrated in university laboratories, start-ups and a few pilots such as CREATE in Warsaw and SaltX in Berlin. No significant mining or manufacturing footprint exists yet; materials such as limestone are quarried almost everywhere.27

Circular economy and end of life

Mixed

Spent salts, oxides and lime are generally benign and can be disposed of or reprocessed with ordinary industrial methods. No end-of-life studies were found.8

Sources

  1. Review of Carnot Battery Technology Commercial Development (Novotny et al., Energies 15(2), 647) MDPI, 2022
  2. Compact thermochemical heat storage prototype (CREATE project, IEA SHC Task 58) IEA Solar Heating and Cooling Programme, 2020
  3. Developments in calcium/chemical looping and metal oxide redox cycles for high-temperature thermochemical energy storage: A review (Yan et al., Fuel Processing Technology 199, 106280) Cranfield University repository, 2020
  4. Life cycle and environmental assessment of calcium looping (CaL) in solar thermochemical energy storage (Colelli et al., Energy Conversion and Management 257, 115428) Elsevier, 2022