Sustainability and environmental concerns are critical issues in energy sector. Limited availability of fossil resources, environmental pollution caused by the greenhouse gases emitted as a result of fossil fuel usage and safety issues of nuclear power plants cause the seek of new resources in energy industry. Renewable energy sources emerge as the alternative energy resources for the industry. The unlimited availability of most of the renewable resources meets the sustainability needs in the energy sector. Energy generation from renewable resources causes low greenhouse gas emissions, which eliminates the environmental concerns. Moreover, use of renewable resources does not involve risks like radioactive emissions. Despite all these factors, renewable energy resources are not competitive yet. The cost of energy generation from renewable resources is high compared to the cost of using conventional resources like coal for energy generation. This situation acts as a barrier for the development of renewable energy technologies and cost reduction. In order to bring renewable energy to a competitive level in the energy market, some supportive mechanisms have been developed and implemented in various countries. This thesis work examines the mechanisms in the EU, the USA and Turkey. An examination has been performed on the current laws and policies effective on renewable energy sector in Turkey. As a result of the examinations, recommendations have been made to improve the legislative framework for the promotion of renewable energy in Turkey.