# Thermochemical biomass conversion

Heat breaks biomass down into gas, oil or char.

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

Capture · Bioenergy · No. 42

- Capture
- Output: Gas, oil, char
 Capture · Bioenergy · Foundation · Energy

Heat dry wood to about 500 C for a second or two without oxygen, and up to 75% of it turns liquid.

Chart: Illustration: Thermochemical biomass conversion

##### Where it comes from

Chart: Map of where it comes from

Starve hot biomass of oxygen and it falls apart: fast pyrolysis at about 500 C gives mostly oil, slow heating at 400 C mostly char, gasification at 800 C mostly gas.

##### Three things to know

1. Bio-oil is not crude oil: it is about 25% water and holds roughly 40% of fuel oil's energy by weight.
2. Torrefaction roasts biomass at 200-350 C into a dry, water-resistant bio-coal that keeps about 82% of its mass.
3. Making one tonne of Fischer-Tropsch fuel takes about 5.6-7.1 t of crop or forest residue.

##### The journey

1. 1 **Biomass**Wood, crop residues, sludge or algae
2. 2 **Heating**Little or no oxygen, 200-800 C
3. 3 **Splitting**Gas, oil and char in varying shares
4. 4 **Upgrading**Tars cleaned; hydrogen strips oxygen from oils
5. 5 **Products**Power, heating oil, bio-coal, jet fuel

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## Other sections

- [Overview](https://www.materialinsights.org/energy/e_bio_thermochem/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_bio_thermochem/correlation/index.md)
- [Efficiency](https://www.materialinsights.org/energy/e_bio_thermochem/efficiency/index.md)
- [Techniques](https://www.materialinsights.org/energy/e_bio_thermochem/techniques/index.md)
- [Resources and labour](https://www.materialinsights.org/energy/e_bio_thermochem/resources/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_bio_thermochem/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_bio_thermochem/links/index.md)