What is the definition?
Renewable energy is generally defined as energy that comes from resources that are naturally replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat.
Renewable energy sources
Flowing water creates energy that can be captured and turned into electricity. This is called hydroelectric power or hydro-power.
Wind energy is the kinetic energy of the wind around the earth. This is an indirect kind of solar energy: solar radiation absorbed into the atmosphere causes differences in temperature and pressure. As a result, the air masses move and accumulate kinetic energy.
Solar power is energy from the sun that is converted into thermal or electrical energy. Solar energy is the cleanest and most abundant renewable energy source available.
Biomass is biological material derived from living, or recently living, organisms. It most often refers to plants or plant-based materials but animal waste can also be considered biomass.
Thermal energy means “heat energy”. Geothermal energy is the heat energy of the Earth’s crust. It comes from the original formation of the planet and from radioactive decomposition of materials.
Biogas belongs to the category of bio-fuels and is a renewable source of energy. Biogas is produced from the breakdown of biological material in the absence of oxygen (the lack of oxygen is called anaerobic condition).
Ocean is also becoming a more a more popular renewable energy source. There are two ways of capturing energy from it: by capturing the tide, or by interacting with the waves created by the wind blowing on the water surface.