Renewable energy is energy derived from renewable resources as opposed to non-renewable, finite resources such as coal and petroleum. Renewable resources which are replenished naturally include rivers, sunlight, wind, tides, rain, waves and geothermal heat, and each of these can provide energy, usually in the form of electricity. However, transforming the energy load of sunlight, waves, etc. into usable electric power can and usually does involve complex technical procedures, the environmental and social cost of which must be taken into account in order to accurately evaluate the costs and benefits of each. This section includes information and opinions about the pros and cons of various forms of renewable energy.