Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlight, wind, rain, tides, waves and geo-thermal heat. Renewable energy replaces conventional fuels in four distinct areas: electricity generation, hot water/space heating, motor fuels, and rural (off-grid) energy services. As a summary, Hydro Power (energy that come from water; you can use dams or water powered cars to transfer energy into electricity), Solar Power (energy that comes from the sun; you can use solar panels to transfer the energy into electricity), Wind Power (energy that comes from the wind; you can use windmills to transfer energy into electricity, Ethonal (energy that comes from corn; you can use ethanol powered cars to transfer energy into electricity), Geothermal (energy from ground source heat pumps; you can get geothermal energy from a geothermal power plant and use the energy to heat your water and home) Biomass (Energy from plants and animals; you can use biofuels for in your car and to heat your home) Tidal Power (Energy from the ocean's tidal currents; use dams to trap the tides and power homes and factories).