Material Insights · Understanding the Material World

Latent heat and cold storage: Impact and additionality

Moving air conditioning out of the dirtiest peak hours

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.

Cold storage targets the air-conditioning peak, which in hot countries coincides with the evening hours gas plants serve. Its impact depends on shifting load into clean hours, not on cutting total energy.

Grid decarbonisation versus fossil displacement

Favourable

Ice moves cooling demand out of the late-afternoon peak, the hours most often met by gas peakers, and into night or midday solar hours. CALMAC estimates up to 1.6 lb of peak CO2 avoided per kWh shifted, a vendor figure that depends on the local grid. Duration is short, usually one day's cycle. Hot PCM stores could replace gas furnaces if they work at scale. Liquid nitrogen has been trialled as stored cold for lorry refrigeration: reports of a Leeds trial cite up to 80% lower greenhouse gas emissions than diesel-driven units and no local air pollution, a developer claim that depends on how the nitrogen is made; the developer, Dearman, entered administration in late 2019.121213

Peak CO2 avoided (company claim) up to 1.6 lb per kWh shifted2 Cooling storage worldwide over 13.9 GWh in about 160 projects1 Liquid nitrogen lorry refrigeration vs diesel (developer claim) up to 80% less greenhouse gas12

Just transition and local community impact

Mixed

Ice and PCM systems are built and serviced by local HVAC trades and use common materials. China has installed more than 1.5 GWh of composite PCM heating stores, an example of domestic manufacturing. The high-temperature segment shows the risk to workers and investors: Azelio, with 153 staff in 2020, filed for bankruptcy in July 2023.19

Composite PCM heating, China over 1.5 GWh installed1 Azelio staff (2020) 1539

Circular economy and end of life

Favourable

Ice tanks are steel or polyethylene with water and glycol, all recoverable. Salt hydrates and paraffins can in principle be recovered, but no recycling statistics were found. Silicon and aluminium can be remelted.6

Sources

  1. Innovation Outlook: Thermal Energy Storage IRENA, 2020
  2. Thermal Battery systems: CALMAC ice storage (Trane sales brochure IB-SLB001, company data) Trane Technologies, 2020
  3. Study on the hybrid energy storage for industrial park energy systems, Table 2: thermal storage materials (National Science Open 3(3)) National Science Open, 2024
  4. Is Azelio's abrupt bankruptcy a bad omen for long-duration energy storage? (news report) Canary Media, 2023
  5. Leeds to trial liquid nitrogen engines (Dearman transport refrigeration, with Cenex and Leeds City Council) (developer claims as reported) The Engineer, 2018
  6. Dearman Engine Company enters administration Jones Day, 2020