Geothermal power (from the Greek words geo, meaning earth, and thermal, meaning heat) is energy generated by heat stored beneath the Earth’s surface or the collection of absorbed heat in the atmosphere and oceans. Prince Piero Ginori Conti tested the first geothermal generator on 4 July 1904, at the Larderello dry steam field in Italy.[1] The largest group of geothermal power plants in the world is located in The Geysers, a geothermal field in California.[2] As of 2007, geothermal power supplies less than 1% of the world’s energy.
Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work - including electricity generation, desalination, and the pumping of water (into reservoirs). Wave power is a form of renewable energy. Though often co-mingled, wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not currently a widely employed commercial technology.
On December 18, 2007, Pacific Gas and Electric Company announced its support for plans to build America’s first commercial wave power plant off the coast of Northern California.The plant will consist of eight buoys, 2 1/2 miles offshore, each buoy generating electricity as it rises and falls with the waves. The plant is scheduled to begin operating in 2012, generating a maximum of 2 megawatts of electricity. Each megawatt can power about 750 homes.
The world’s first commercial wave farm is based in Portugal,at the Aguçadora Wave Park, which consists of three 750 kW Pelamis devices. Other plans for wave farms include a 3MW array of four 750 kW Pelamis devices in the Orkneys, off northern Scotland, and the 20MW Wave hub development off the north coast of Cornwall, England.
The north and south temperate zones have the best sites for capturing wave power. The prevailing westerlies in these zones blow strongest in winter.
Solar energy is the heat and light radiated from the Sun that drives Earth’s climate and supports life. Solar technologies make controlled use of this energy resource. Solar power is a synonym of solar energy or refers specifically to the conversion of sunlight into electricity by photovoltaics, concentrating solar thermal devices or various experimental technologies.
The controlled use of solar energy is an important consideration in building design. Thermal mass is used to conserve the heat that sunshine delivers to all buildings. Daylighting techniques optimize the use of light in buildings. Solar water heaters heat swimming pools and provide domestic hot water. In agriculture, greenhouses grow specialty crops and photovoltaic-powered pumps bring water to grazing animals. Evaporation ponds find applications in the commercial and industrial sectors where they are used to harvest salt and clean waste streams of contaminants.
Solar distillation and disinfection techniques produce potable water for millions of people worldwide. Family-scale solar cookers and larger solar kitchens concentrate sunlight for cooking, drying and pasteurization. More sophisticated concentrating technologies magnify the rays of the Sun for high temperature material testing, metal smelting and industrial chemical production. A range of prototype solar vehicles provide ground, air and sea transportation.
Biomass refers to living and recently dead biological material that can be used as fuel or for industrial production. Most commonly, biomass refers to plant matter grown for use as biofuel, but it also includes plant or animal matter used for production of fibres, chemicals or heat. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum.
Biomass is grown from several plants, including miscanthus, switchgrass, hemp, corn, poplar, willow, sugarcane, and oil palm (palm oil). The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material. Production of biomass is a growing industry as interest in sustainable fuel sources is growing.
Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been “out” of the carbon cycle for a very long time. Their combustion therefore disturbs the carbon dioxide content in the atmosphere.
Plastics from biomass, like some recently developed to dissolve in seawater, are made the same way as petroleum-based plastics, are actually cheaper to manufacture and meet or exceed most performance standards. But they lack the same water resistance or longevity as conventional plastics.
Wind power is the conversion of wind energy into a useful form, such as electricity, using wind turbines. At the end of 2007, worldwide capacity of wind-powered generators was 94.1 gigawatts.Although wind currently produces about 1% of world-wide electricity use, it accounts for approximately 19% of electricity production in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland (2007 data). Globally, wind power generation increased more than fivefold between 2000 and 2007.
Most wind power is generated in the form of electricity. Large scale wind farms are connected to electrical grids. Individual turbines can provide electricity to isolated locations. In windmills, wind energy is used directly as mechanical energy for pumping water or grinding grain.
Wind energy is plentiful, renewable, widely distributed, clean, and reduces greenhouse gas emissions when it displaces fossil-fuel-derived electricity. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand, but it presents extra costs when wind is to be used for a large fraction of demand. However these costs even for quite large percentage penetrations are considered to be modest.
The siting of turbines has become a controversial issue amongst those concerned about the value of natural landscapes, particularly since the best sites for wind generation tend to be in scenic mountain and oceanside areas.