Renewable energy

Renewable energy is energy generated from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable (naturally replenished). In 2006, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass such as wood-burning and 3% from hydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for 2.4% grow very rapidly. The share of renewables in electricity generation is about 18%, with 15% of global electricity coming from hydroelectricity and 3.4% from new renewables.

Wind power is growing at the rate of 30% annually with a worldwide installed capacity of 121, 000 megawatts (MW) in 2008 and is widely used in European countries and the United States. Solar thermal power stations operate in the USA and Spain, and the largest of them 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. Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18% of the country's automotive fuel. Ethanol fuel is also widely available in the USA.

While most renewable energy projects and production is large-scale, renewable technologies are also suited to small off-grid applications, sometimes in rural and remote areas, where energy is often crucial in human development. Kenya has the world's highest household solar ownership rate with roughly 30, 000 small (20–100 watt) solar power systems sold per year.

Some renewable energy technologies are criticized for being intermittent or unsightly, yet the renewable energy market continues to grow. Climate change concerns, coupled with high oil prices, peak oil, and increasing government support, are driving increasing renewable energy legislation, incentives and commercialization.

The majority of renewable energy technologies are powered by the sun. 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 roughly 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. Wave motion may play a role in the process of transferring mechanical energy between the atmosphere and the ocean through wind stress. Solar energy is also responsible for the distribution of precipitation which is tapped by hydroelectric projects, and for the growth of plants used to create biofuels.

Renewable energy flows involve natural phenomena such as sunlight, wind, tides and geothermal heat, as the International Energy Agency explains.

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.

Ex 3. Answer the following questions:

1) What is renewable energy?
2) What natural resources of energy do you know?
3) What are new renewables?
4) What is the capacity of world’s largest geothermal power installation?
5) What is the majority of renewable energy technologies powered by?
6) What absorbs a major fraction of the incoming radiation?
7) Where is most radiation absorbed?
8) What is solar energy responsible for?