# Waste heat for drying, water and food

Low-grade heat put to work drying products, making fresh water and warming greenhouses.

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

Recovery and reuse · Heat to heat · No. 124

- Recovery and reuse
- Heat grade: Low to medium
 Recovery and reuse · Heat to heat · Foundation · Energy

Heat too cool to boil anything can still make fresh water, dry grain and grow tomatoes, if it is free.

Chart: Illustration: Waste heat for drying, water and food

##### Where it comes from

Chart: Map of where it comes from

Drying, desalination, greenhouses and carbon capture can all run on low-grade heat. ORNL estimates about 570 TBtu a year of US industrial waste heat sits below 149 C.

##### Three things to know

1. Multi-effect distillation runs at about 70 C, cool enough to use heat that boilers and furnaces throw away.
2. Bought at gas prices, the heat alone would add about USD 1.6 per cubic metre of water, so thermal desalination needs truly free heat.
3. Using a cement plant's full waste heat cut carbon capture cost from EUR 61.4 to 48.0 per tonne of CO2.

##### The journey

1. 1 **Spare heat**Exhaust or cooling water from a host
2. 2 **Heat loop**Pipes carry it to a neighbour
3. 3 **End use**Desalination, drying, greenhouses, carbon capture
4. 4 **Product**Fresh water, dried grain, tomatoes, CO2
5. 5 **Backup**Boiler on standby if host stops

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_waste_heat_uses/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_waste_heat_uses/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_waste_heat_uses/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_waste_heat_uses/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_waste_heat_uses/rc-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_waste_heat_uses/rc-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_waste_heat_uses/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_waste_heat_uses/links/index.md)