Renewable Energy Solar
Photovoltaics (PV) involve the conversion of energy from the sun into electricity by means of semiconductors. The solar energy excites electrons so that they break free from their atoms, allowing the electrons to flow through the semiconductor material to produce electricity.
There are a number of PV technologies including polycrystalline, mono-crystalline and thin-film. Solar PV cells are generally arranged in panels. In smaller applications they can be installed on a building's roof or walls and feed electricity directly into the building for use as lighting or power or alternatively feed into the electricity grid. In larger applications the panels can be installed in greater quantities as dedicated energy generation facilities and feed into the electricity grid to supply whole communities.
Wind
The use of wind as a renewable energy resource involves harnessing the power contained in moving air. Wind represents a vast source of energy which man has harnessed for hundreds of years.
Wind turbines are mounted on towers to optimize energy capture. At 30 meters or more above ground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor. Wind turbines use aerodynamic forces ('lift' and 'drag') to produce mechanical power that can then be converted to electricity.
Wind turbines can be used as stand-alone applications for water pumping or communications, or they can be connected to a utility power grid.
Small wind generators rated at a few watts are available for battery charging and meeting small on-site power needs etc. Large-scale generation of electricity requires building a large number of wind turbines to form wind farms. The machines are usually spaced around five rotor diameters apart to ensure they do not interfere with each other's performance.
Wind farms can be situated either onshore or offshore. The latter is an arena which is just beginning to be significantly developed but which has enormous potential.
Tidal
Tidal energy exploits the natural ebb and flow of coastal tidal waters caused principally by the interaction of the gravitational fields of the Earth-Moon-Sun system.
The coastal water level fluctuates twice daily, alternatively filling and emptying natural basins along the shoreline. The currents flowing in and out of these basins can be exploited to turn mechanical devices to produce electricity. A variant of tidal energy is tidal stream (or marine current) technology. Tidal streams are fast sea currents created by the tides, often magnified by topographical features such as headlands and inlets and straits or by the shape of the seabed.
The technology required to convert tidal energy into electricity is very similar to that used in traditional hydroelectric power plants. The first requirement in tidal energy is a dam or 'barrage' across a tidal bay or estuary. Gates and turbines are installed along the dam. When there is an adequate difference in the height of water on either side of the dam the gates are opened. This 'hydrostatic head' that is created causes water to flow through the turbines, turning an electric generator to produce electricity. Electricity can be generated by water flowing both into and out of a bay. As there are two high and two low tides each day, electrical generation from tidal power plants is characterized by periods of maximum generation every 12 hours.
Wave
The energy contained in ocean waves can potentially provide an unlimited source of renewable energy.
Ocean waves are created by the interaction of wind with the surface of the sea. Waves are a dense form of energy compared, for example, to the wind. Because water is much denser than air, so the energy required to move a volume of water is far greater than that needed to move the same volume of air.
Wave energy can be extracted and converted into electricity by wave power machines. They can be deployed either on the shoreline or in the deeper waters offshore.
Biomass
Biomass, also known as biofuels or bioenergy, is obtained from organic matter either directly from plants or indirectly from industrial, commercial, domestic or agricultural products.
The use of biomass is classed as a 'carbon neutral' process because the carbon dioxide released during the generation of energy from biomass is balanced by that absorbed by plants during their growth.
Biomass falls into two main groups.
Woody biomass - forest products, untreated wood products, waste wood, straw, and energy crops such as willow and poplar.
Non-woody biomass - human and animal wastes e.g. slurry, chicken litter, industrial and municipal biodegradable wastes including food processing wastes. Also high energy crops such as rape, wheat, barley and sugar beet, sugar cane and maize, which can be processed to produce the biofuels, bioethanol and biodiesel.
Biomass can be converted into heat and electricity in a number of ways. Depending on its source, these processes include: burning, pyrolysis, gasification, anaerobic digestion or fermentation.
Photovoltaics (PV) involve the conversion of energy from the sun into electricity by means of semiconductors. The solar energy excites electrons so that they break free from their atoms, allowing the electrons to flow through the semiconductor material to produce electricity.
There are a number of PV technologies including polycrystalline, mono-crystalline and thin-film. Solar PV cells are generally arranged in panels. In smaller applications they can be installed on a building's roof or walls and feed electricity directly into the building for use as lighting or power or alternatively feed into the electricity grid. In larger applications the panels can be installed in greater quantities as dedicated energy generation facilities and feed into the electricity grid to supply whole communities.
Wind
The use of wind as a renewable energy resource involves harnessing the power contained in moving air. Wind represents a vast source of energy which man has harnessed for hundreds of years.
Wind turbines are mounted on towers to optimize energy capture. At 30 meters or more above ground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor. Wind turbines use aerodynamic forces ('lift' and 'drag') to produce mechanical power that can then be converted to electricity.
Wind turbines can be used as stand-alone applications for water pumping or communications, or they can be connected to a utility power grid.
Small wind generators rated at a few watts are available for battery charging and meeting small on-site power needs etc. Large-scale generation of electricity requires building a large number of wind turbines to form wind farms. The machines are usually spaced around five rotor diameters apart to ensure they do not interfere with each other's performance.
Wind farms can be situated either onshore or offshore. The latter is an arena which is just beginning to be significantly developed but which has enormous potential.
Tidal
Tidal energy exploits the natural ebb and flow of coastal tidal waters caused principally by the interaction of the gravitational fields of the Earth-Moon-Sun system.
The coastal water level fluctuates twice daily, alternatively filling and emptying natural basins along the shoreline. The currents flowing in and out of these basins can be exploited to turn mechanical devices to produce electricity. A variant of tidal energy is tidal stream (or marine current) technology. Tidal streams are fast sea currents created by the tides, often magnified by topographical features such as headlands and inlets and straits or by the shape of the seabed.
The technology required to convert tidal energy into electricity is very similar to that used in traditional hydroelectric power plants. The first requirement in tidal energy is a dam or 'barrage' across a tidal bay or estuary. Gates and turbines are installed along the dam. When there is an adequate difference in the height of water on either side of the dam the gates are opened. This 'hydrostatic head' that is created causes water to flow through the turbines, turning an electric generator to produce electricity. Electricity can be generated by water flowing both into and out of a bay. As there are two high and two low tides each day, electrical generation from tidal power plants is characterized by periods of maximum generation every 12 hours.
Wave
The energy contained in ocean waves can potentially provide an unlimited source of renewable energy.
Ocean waves are created by the interaction of wind with the surface of the sea. Waves are a dense form of energy compared, for example, to the wind. Because water is much denser than air, so the energy required to move a volume of water is far greater than that needed to move the same volume of air.
Wave energy can be extracted and converted into electricity by wave power machines. They can be deployed either on the shoreline or in the deeper waters offshore.
Biomass
Biomass, also known as biofuels or bioenergy, is obtained from organic matter either directly from plants or indirectly from industrial, commercial, domestic or agricultural products.
The use of biomass is classed as a 'carbon neutral' process because the carbon dioxide released during the generation of energy from biomass is balanced by that absorbed by plants during their growth.
Biomass falls into two main groups.
Woody biomass - forest products, untreated wood products, waste wood, straw, and energy crops such as willow and poplar.
Non-woody biomass - human and animal wastes e.g. slurry, chicken litter, industrial and municipal biodegradable wastes including food processing wastes. Also high energy crops such as rape, wheat, barley and sugar beet, sugar cane and maize, which can be processed to produce the biofuels, bioethanol and biodiesel.
Biomass can be converted into heat and electricity in a number of ways. Depending on its source, these processes include: burning, pyrolysis, gasification, anaerobic digestion or fermentation.
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