# Firewood and charcoal supply: How it works

From felled tree to a tin of charcoal in a city kitchen

Source page: https://www.materialinsights.org/energy/e_traditional_fuel/explain/

What this tab covers How the energy actually moves, step by step: the science that makes it work and the engineering that makes it practical.

Wood and charcoal are still the main cooking fuels for a very large number of households, mostly in sub-Saharan Africa and South Asia. Firewood is usually gathered and carried short distances by hand, while charcoal is made in the countryside and moved in bags by bicycle, motorbike and lorry to cities.

#### Step by step

1. **Cut and gather wood**Rural households collect dead or cut wood and carry it home as head-loads or bundles. Charcoal makers fell trees on farmland, community land or forest; in a Kenyan survey 49% used their own farmland and 42% community forests and trust lands.
2. **Carbonise in an earth kiln**Wood is stacked, covered with soil and burned slowly with little air for about a week, then cooled. A Tanzanian kiln produced about 23 bags and took two men about 18 days of work.
3. **Bag and move to the roadside**Charcoal is packed in sacks (a Tanzanian standard bag is 75 kg, though producer bags averaged about 72 kg) and carried by bicycle, motorbike or ox cart to a road; a bicycle can carry more than two 90 kg bags.
4. **Truck to the city**Lorries carry loads from several producers to urban depots; Mozambican surveys put a lorry at 70 to 100 sacks. In Tanzania, charcoal may only be moved between 6am and 6pm in open trucks, and transit passes are needed to leave the district.
5. **Wholesale and retail**Wholesalers split bags into 10, 50 or 70 kg units, and retailers sell small tins or bags to households for daily cooking.

#### The science

Charcoal is wood that has been heated without enough oxygen to burn, driving off water and volatile gases and leaving mostly carbon. It holds more energy per kilogram than wood, burns with little smoke and does not rot or attract insects, which makes it worth carrying long distances to cities. The price is a large energy loss in the kiln: the simple kilns used in most low-income countries keep only about 10 to 22% of the wood's energy, the rest escaping as smoke and gas. Kiln yields of 12 to 40% by dry weight imply roughly 2.5 to 8 kg of dry wood per kilogram of charcoal (calculated), and Tanzanian planners use about 10 kg of (wetter) wood per kg.

#### The engineering

The equipment is simple: axes and saws, earth mound kilns, sacks, bicycles and second-hand lorries. Improved kilns (brick kilns, the Casamance kiln with a chimney) raise yield by controlling airflow. The supply system is largely informal, organised through networks of producers, transporters, wholesalers and retailers rather than firms.

#### Key numbers
 World wood fuel removals (2019 estimate) 2,525.7 million cubic metres, about 30% above earlier figures^[1](https://doi.org/10.1038/s41467-025-59733-y) World charcoal production (new estimate) 70.5 million tonnes, about 50% above earlier figures^[1](https://doi.org/10.1038/s41467-025-59733-y) People relying mainly on polluting cooking fuels (wood, charcoal, dung, kerosene) About 2.1 billion^[9](https://www.who.int/teams/environment-climate-change-and-health/air-quality-and-health/sectoral-interventions/household-air-pollution/health-risks) People working in commercial fuelwood and charcoal More than 40 million worldwide^[2](https://www.uncclearn.org/wp-content/uploads/library/charcoal.pdf) Typical haul distances 124 km average into Kigali; 300 to 600 km for Malawi plantation charcoal; may approach 1,000 km^[3](https://rael.berkeley.edu/old-site/Kammen.charcoal.pdf) Tanzania charcoal use About 1 million tonnes a year, half in Dar es Salaam^[4](https://openknowledge.worldbank.org/bitstreams/6c4e03ca-a24d-5406-8559-308b3a1c6d35/download)

#### Sources

1. [Global wood fuel production estimates and implications (Steel et al., Nature Communications 16, 6227; authors include FAO staff)](https://doi.org/10.1038/s41467-025-59733-y) Nature Portfolio, 2025
2. [The charcoal transition: greening the charcoal value chain to mitigate climate change and improve local livelihoods](https://www.uncclearn.org/wp-content/uploads/library/charcoal.pdf) FAO, 2017
3. [Review of technologies for the production and use of charcoal (Kammen and Lew)](https://rael.berkeley.edu/old-site/Kammen.charcoal.pdf) Renewable and Appropriate Energy Laboratory, UC Berkeley, 2005
4. [Environmental Crisis or Sustainable Development Opportunity? Transforming the Charcoal Sector in Tanzania: A Policy Note](https://openknowledge.worldbank.org/bitstreams/6c4e03ca-a24d-5406-8559-308b3a1c6d35/download) World Bank, 2009
5. [Household air pollution: health risks](https://www.who.int/teams/environment-climate-change-and-health/air-quality-and-health/sectoral-interventions/household-air-pollution/health-risks) World Health Organization, 2026

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_traditional_fuel/index.md)
- [Overview](https://www.materialinsights.org/energy/e_traditional_fuel/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_traditional_fuel/correlation/index.md)
- [Efficiency and losses](https://www.materialinsights.org/energy/e_traditional_fuel/efficiency/index.md)
- [Technology advances](https://www.materialinsights.org/energy/e_traditional_fuel/advances/index.md)
- [Value chain](https://www.materialinsights.org/energy/e_traditional_fuel/valuechain/index.md)
- [Geopolitics and regulation](https://www.materialinsights.org/energy/e_traditional_fuel/geopolitics/index.md)
- [Unit economics](https://www.materialinsights.org/energy/e_traditional_fuel/economics/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_traditional_fuel/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_traditional_fuel/links/index.md)