Green energy is a term used to describe sources of energy that are considered to be environmentally friendly and non-polluting, such as geothermal, wind, and solar power. These sources of energy may provide a remedy to the systemic effects of global warming and certain forms of pollution.

Green energy is commonly thought of in the context of electricity, heating and cogeneration. Consumers, businesses, and organizations may purchase green energy in order to support further development, help reduce the environmental impacts of conventional electricity generation, and increase their nation's energy independence. Renewable energy certificates (Green certificates or green tags) have been one way for consumers and businesses to support green energy. Over 35 million homes in Europe and 1 million in the United States are purchasing such certificates.

Additionally, some governments have drafted specific definitions for green energy or similar terms that may be eligible for subsidies and support for related technologies.