Alternative energy refers to the various forms of energy that are produced by means other than the traditional burning of fossil fuels. Burning fossil fuels (like coal) to create power is effective but very damaging to the environment, as it releases harmful greenhouse gases, namely carbon dioxide (CO2) that contribute to global warming (or "climate change"). Examples of alternative energy sources: wind, solar, geothermal, hydroelectric, nuclear, biofuel and others. (Photo: Flickr)