Renewable energy comes from resources which are continually renewed by natural processes, such as sunlight, wind, rain, tides, and geothermal heat.
Renewable energy is potentially environmentally friendly, but not always. The "old" renewables, biomass and hydroelectricity, generally have massive negative impacts:
- Burning biomass creates smoke, and indoor pollution which is a major cause of infant mortality in less developed communities.
- Dams, used for large-scale hydroelectric projects, cause massive environmental disruption, interfering with fish migration and breeding, preventing the natural flow of sediment and nutrients, and interrupting the natural water cycle with sometimes unpredictable consequences (such as the outbreak of the parasitic illness schistosomiasisW following the year-round irrigation introduced by the Aswan Dam .
In 2006, about 18% of global final energy consumption came from renewables, but this is almost all from the old, damaging renewables: 13% from traditional biomass, mainly for heating, and 3% from hydroelectricity. "New" renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for only 2.4%, but are growing very rapidly.[verification needed]