Renewable Energy is a source of energy that is a renewable resource unlike non-renewables like coal, nuclear, natural gas or petroleum.
Major sources of renewable energy include solar PV and concentrated solar technologies, wind, wave power, geothermal, biofuels like bio-diesel, alcohols such as ethanol, biogas and gasification.
Any real effort to mitigate Global Climate Change will involve both serious initiatives to reduce consumption and waste as well as the radical ramping up of renewable technologies through major investments in research coupled with the subsidization of these technology as they struggle to achieve economies of scale.