Renewable energy is commonly understood to be energy generated from natural resources.  These resources include: sunlight, wind, rain, tides and geothermal heat, which are renewable (naturally replenished). According to the Global Status Report 2007, in 2006, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood-burning. Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generation),followed by solar hot water/heating, which contributed 1.3%. Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided 0.8% of final energy consumption.

According to the European Wind Energy Association, and the Global Wind Energy Council, wind power is growing at the rate of 30 percent annually, with a worldwide installed capacity of over 100 GW, and is widely used in several European countries and the United States. One of the largest, if not the largest, producers of wind technology is Vestas, a Danish company. The manufacturing output of the photovoltaics industry reached more than 2,000 MW in 2006 (According to The Clean Tech Revolution), and photovoltaic (PV) power stations are particularly popular in Germany and Spain. Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert. The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW.

Renewable technologies are also well-suited to smaller, off-the-grid applications.  In fact, Kenya has the world's highest household solar ownership rate with roughly 30,000 (20-100 watt) solar power systems sold per year. (What Solar Power Needs Now - Renewable Energy Acess, 13 August 2007)

Renewable energy technologies are often times criticised for being intermittent or unsightly.  Recently headlines were made by an East Coast township that didn't want wind turbines placed offshore because it might disturb their 'views'.  However, the market continues to grow and these types of arguments will be dismissed as irresponsible and short-sighted.

Global warming and climate change concerns coupled with high oil prices, peak oil and increasing government support are creating renewable energy legislation, incentives and commercialization. New government spending and a supportive administration allocating the financial resources, writing the regulations and policies should help the renewable energy markets avoid much of the current (2008 and 2009) economic crisis to a large degree.

Solar is probably the best known renewable energy technology.  Powered by the ultimate renewable resource, sunlight. The Earth-Atmosphere system is in equilibrium such that heat radiation into space is equal to incoming solar radiation, the resulting level of energy within the Earth-Atmosphere system can be described as the Earth's "climate." The hydrosphere (water) absorbs a major fraction of the incoming radiation. Most radiation is absorbed at low latitudes around the equator, but this energy is dissipated around the globe in the form of winds and ocean currents. According to Renewable Energy, Sorensen, Elsevier 2004, wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress.

Renewable energy as explained by the International Energy Agency is:

"Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources." (Renewable energy... into the mainstream p. 9)

All of these various 'resources' are unique and have characteristics which determine where and how they can be used.  Continue to explore this site further for explanations of the individual resources and their technologies.