Latent heat and cold storage
Storing energy by melting or freezing a material, or by keeping things cold.
Storage · Thermal · No. 84
- Storage
- Duration: Hours to days
A New York skyscraper makes ice at night to cool offices by day, cutting peak demand by up to 2.1 MW.
Chart: Illustration: Latent heat and cold storage
Where it comes from
Chart: Map of where it comes from
Water, salt hydrates, paraffins or even molten silicon soak up heat as they melt and release it as they freeze, at a nearly fixed temperature.
Three things to know
- Melting packs a lot of energy into a narrow temperature band: salt hydrates take in 100 to 290 J per gram.
- Molten silicon at 1,414 C can hold about 500 kWh per tonne, but hot-metal developers have struggled, with Azelio bankrupt in 2023.
- One vendor's ice tank, about half a parking space, can deliver 40 tons of cooling for 8 hours.
The journey
- 1 Night powerCheap off-peak or midday solar electricity
- 2 ChillerRuns colder to freeze water
- 3 Ice tanksHold cooling at a steady 0 C
- 4 MeltIce absorbs heat as it thaws
- 5 Cool buildingAir conditioning without the afternoon peak