Energy affects all aspects of modern life. The demand for energy is increasing at an exponential rate due to the exponential growth of world population. Oil and gas are expected to continue to be important sources of energy. Contemporary electric power generation is based on non-renewable resources such as oil, coal, and nuclear power. New efficient and cost-effective small-scale renewable energy generation options are commercially available today. The share of renewable energy sources is expected to increase very significantly. Alternative energy technologies are being disseminated in many countries with an objective to reduce the uses of traditional and commercial energy sources. For each country, the choice between the various available options is strongly dependent on the local condition.