6. Fuel – different fuels compared to wood by calorific value.

In the table below, wood has been allocated an arbitary value of 1 so that we can compare other fuels with it directly. Note that when wood is converted to charcoal it effectively becomes pure carbon and has a calorific value equal to the finest quality coals.
XXThe calorific value of cattle dung is virtually identical to wood, making it an important energy source in the Third World. This is unfortunate since when fuel is scarce (as is often the case,) it gets burned instead of being returned to the land to to improve soil fertility.