Energy

Abstract

The current total world energy use is around 6,800 million tons of coal equivalent. Our world energy budget is of course made up from several different energy forms, the most important of which are coal, oil and natural gas. It is however convenient to express them all in terms of the equivalent amount of coal. This unit, the tonne★ of coal equivalent, or t.c.e., is easy to visualise, we all know what a tonne of coal looks like, and it turns out to be about the right size to express personal annual energy consumption. The world use of commercial energy per year per capita is 1.9 t.c.e. The rate at which energy is used is called power✝ and the units we shall use are the kilowatt (kW) and the horse power (h.p. approximately 3/4 kW). T.c.e. per year is numerically very nearly the same as kW, so our average world energy use of 1.9 t.c.e. per year is the same as a two-bar electric fire burning continuously. In these units the energy equivalent of our food is 0.17 t.c.e. per year or about 1 lb of coal a day; in power terms we are all equivalent to two or three 50 W electric light bulbs burning continuously. Most of this energy appears as heat.