Renewable resource
A natural resource qualifies as a renewable resource if it is replenished by natural processes at a rate comparable or faster than its rate of consumption by humans or other users. Solar radiation, tides, and winds are perpetual resources that are in no danger of being used in excess of their long-term availability.
 Available renewable energy. The volume of the cubes represent the amount of available geothermal, wind and solar energy in TW, although only a small portion is recoverable. The small red cube shows the proportional global energy consumption. [1] Some natural renewable resources such as geothermal, fresh water, timber, and biomass must be carefully managed to avoid exceeding the environment's capacity to replenish them. A life cycle assessment provides a systematic means of evaluating renewability.
Alcohol derived from corn, sugar cane, switchgrass, etc. is also a renewable source of energy. Similarly, oils from plants and seeds can be used as a substitute for non-renewable diesel. Methane is also considered as a renewable source of energy.
Gasoline, coal, natural gas, diesel, and other commodities derived from fossil fuels are non-renewable. Unlike fossil fuels, a renewable resource can have a sustainable yield.
Renewable resources may also mean commodities such as wood, paper, and leather.
[edit] Renewable energy
[edit] Solar power
Main article: Solar energy
Solar power is the energy derived from the Sun. It is the most abundant source of energy on Earth.
[edit] Wind power
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Wind power is the conversion of wind energy into more useful forms, usually electricity using wind turbines. At the end of 2007, worldwide capacity of wind-powered generators was 94.1 gigawatts.[2] Although wind currently produces just over 1% of world-wide electricity use,[3] 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.[2]
In 2006, the countries with the highest total installed capacity were Germany (20,621 MW), Spain (11,615 MW), the USA (11,603 MW), India (6,270 MW) and Denmark (3,136 MW).[4]
Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. In windmills (a much older technology) wind energy is used to turn mechanical machinery to do physical work, like crushing grain or pumping water.
Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations.
Wind energy is ample, renewable, widely distributed, clean, and mitigates the greenhouse effect if used to replace fossil-fuel-derived lightning. To make the power, the windmill captures the wind and spins a generator. The generator then produces electricity.
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.[5]
[edit] Geothermal
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Geothermal uses the natural flow of heat from the earths core. About half of the available energy is from natural radiation in the earths crust and mantle. Geothermal and biomass are the only two renewable energies which need to be carefully managed in order to avoid local depletion.
[edit] Hydropower
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Hydropower is the capture of the energy of moving water for some useful purpose. Prior to the widespread availability of commercial electric power, hydropower was used for irrigation, milling of grain, textile manufacture, and the operation of sawmills.
The energy of moving water has been exploited for centuries; in Imperial Rome, water powered mills produced flour from grain, and in China and the rest of the Far East, hydraulically operated "pot wheel" pumps raised water into irrigation canals. In the 1830s, at the peak of the canal-building era, hydropower was used to transport barge traffic up and down steep hills using inclined plane railroads.
Direct mechanical power transmission required that industries using hydropower had to be situated near the waterfall. For example, during the last half of the 19th century, many grist mills were built at Saint Anthony Falls, utilizing the 50 foot (15 meter) drop in the Mississippi River. The mills contributed to the growth of Minneapolis. Today the largest use of hydropower is for electric power generation, which allows low cost energy to be used at long distances from the watercourse.
[edit] Renewable materials
[edit] Agricultural Products
Techniques in agriculture which allow for minimal or controlled environmental damage qualify as sustainable agriculture. Products (foods, chemicals, biofuels, etc) from this type of agriculture may be considered "sustainable" when processing, logistics, etc. also have sustainable characteristics.
Similarly, forest products such as lumber, plywood, paper and chemicals, can be renewable resources when produced by sustainable forest management techniques.
Water can qualify as a renewable material when carefully controlled usage, treatment, and release are followed. If not, it would become a non-renewable resource at that location. For example, groundwater could be removed from an aquifer at a rate greater than the sustainable recharge. Removal of water from the pore spaces may cause permanent compaction (subsidence) that cannot be reversed.
[edit] See also
[edit] References
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