ABSTRACT
This chapter discusses issues related to food and population in the present and the future. Environmentally, energy supply and demand is classified into primary and secondary energies. The former includes petroleum, coal, natural gas, conventional biomass and the latter involves converted energies, such as electric power. Due to the oil crises in the 1970s, depletion of fossil fuels and combustion gases, and the various environmental problems, the focus of research shifted to non-conventional energy resources, such as wind, hydro, and solar energy. Conventional energy sources generally produce substances, such as carbon dioxide, that pollute the environment. Energy sources that continue to be in the available form are called renewable energy sources. Crude oil is a mixture of comparatively volatile liquid hydrocarbons, though it also contains some nitrogen, sulfur, and oxygen. It is a kind of mineral resource. Non-ferrous metals are metals that do not contain iron.
