Energy is the sustenance of our civilization. It is the basic driving force in the maintenance of our well-being - nutrition, health, shelter, transportation, communication, recreation, agriculture, and industry. Most of the energy used by man comes from fossil fuels and is used in the form of natural gas, gasoline and diesel fuel, coal, and electricity. The conventional sources of energy - petroleum, natural gas, coal and hydroelectric - are in finite supply and depletion seems imminent. This is especially true of those forms of energy which have the properties for specific uses, such as gasoline for the internal combustion engine of the automobile. Only when it became difficult to get all the gasoline we wanted did we begin to think in terms of a limited supply