# Latent heat and cold storage

Storing energy by melting or freezing a material, or by keeping things cold.

Source page: https://www.materialinsights.org/energy/e_latent_heat/

Storage · Thermal · No. 84

- Storage
- Duration: Hours to days
 Storage · Thermal · Foundation · Energy

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

1. Melting packs a lot of energy into a narrow temperature band: salt hydrates take in 100 to 290 J per gram.
2. Molten silicon at 1,414 C can hold about 500 kWh per tonne, but hot-metal developers have struggled, with Azelio bankrupt in 2023.
3. One vendor's ice tank, about half a parking space, can deliver 40 tons of cooling for 8 hours.

##### The journey

1. 1 **Night power**Cheap off-peak or midday solar electricity
2. 2 **Chiller**Runs colder to freeze water
3. 3 **Ice tanks**Hold cooling at a steady 0 C
4. 4 **Melt**Ice absorbs heat as it thaws
5. 5 **Cool building**Air conditioning without the afternoon peak
 Covered in [The laws of energy: conservation, entropy and efficiencyEnergy](https://www.materialinsights.org/learn/energy/laws-of-energy/)[Storing energy: from fuel stocks to batteriesEnergy](https://www.materialinsights.org/learn/energy/storing-energy/)

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## Other sections

- [Overview](https://www.materialinsights.org/energy/e_latent_heat/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_latent_heat/correlation/index.md)
- [Science and technology](https://www.materialinsights.org/energy/e_latent_heat/sg-sci/index.md)
- [Engineering and performance](https://www.materialinsights.org/energy/e_latent_heat/sg-eng/index.md)
- [Economics](https://www.materialinsights.org/energy/e_latent_heat/sg-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_latent_heat/sg-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_latent_heat/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_latent_heat/links/index.md)