Boilers, furnaces and stoves

Burning fuel for heat: industrial boilers, kilns, furnaces, gas and biomass stoves.

Conversion and use · Conversion devices · No. 107

• Conversion and use

Burning fuel for heat is about 41% of all energy humanity uses, from 100 MW boilers to three stones under a pot.

Chart: Illustration: Boilers, furnaces and stoves

Where it comes from

Burning joins the carbon and hydrogen in fuel with oxygen, and the hot gas hands its heat to water, metal or a cooking pot. Heat was almost half of world final energy in 2024.

Boilers come from a mix of global groups and national specialists; Vaillant calls itself the world leader in central heating units. In Africa, LPG serves more than 70% of people with clean cooking.

Three things to know

1. A 95% efficient boiler making 60 C water keeps only about 14% of the fuel's ability to do work, because a flame is far hotter than needed.
2. Open fires and the simplest stoves deliver under 10% of their heat to the pot, while good LPG stoves manage about 42 to 70%.
3. In the US, 36% of the energy used for process heating is lost through flues, pipes, steam traps and walls (2010 data).

The journey

1. 1 FuelGas, oil, coal, LPG or wood
2. 2 FlameBurner releases chemical energy as hot gas
3. 3 Heat exchangeTubes or chamber pass heat to water
4. 4 Steam or productSteam, hot water, molten metal, clinker
5. 5 End useDrying, melting, cooking and heating homes

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