# Solar fuels and photosynthesis

Sunlight stored as chemical energy, in crops and forests or in fuels made by artificial photosynthesis.

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

Capture · Solar · No. 25

- Capture
- Output: Fuel / chemicals
 Capture · Solar · Foundation · Energy

Every crop on Earth runs on sunlight, yet a soybean field stores only about 1.6% of it as chemical energy.

Chart: Illustration: Solar fuels and photosynthesis

##### Where it comes from

Chart: Map of where it comes from

Sunlight arrives spread thin, so leaves and machines must gather a lot of it. The thermochemical route focuses it about 2,500 times to heat ceria to roughly 1,500 C.

##### Three things to know

1. Plants hit a hard ceiling: at most 4.6% of sunlight ends up stored in wheat, rice and trees, and 6% in maize or sugar cane.
2. Colour is half the problem: about 51% of incoming sunlight lies outside the band that chlorophyll can use at all.
3. In Spain, a 50 kW solar tower with 169 mirrors has run the whole chain from sunlight, water and CO2 to kerosene.

##### The journey

1. 1 **Sunlight**Plants use only the 400-700 nm band
2. 2 **Light capture**Chlorophyll, semiconductor or mirror field
3. 3 **Water splitting**Oxygen released, hydrogen freed
4. 4 **Carbon fixing**CO2 built into sugars or syngas
5. 5 **Food and fuel**Crops, wood, hydrogen, solar kerosene

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## Other sections

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