United Nations World Commission on Environment and Development, Brundtland Report (1987)
“ At present, the energy to provide these services comes from fuels – oil, gas, coal, nuclear, wood, and other primary sources (solar, wind, or water power) – that are all useless until they are converted into the energy-services needed by machines or other kinds of end-use equipment, such as stoves, turbines, or motors. In many countries worldwide, a lot of primary energy is wasted because of the inefficient design or running of the equipment used to convert it into the services required; though there is an encouraging growth in awareness of energy conservation and efficiency. ”
