Renewable resource
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A natural resource qualifies as a renewable resource if its stock (quantity) can increase over time.
Natural resources which thus qualify as renewable resources are, for example, oxygen, fresh water, solar energy, timber, and biomass. However they can become non-renewable resources if used at a greater rate that the environment's capacity to replenish them. For example ground water may be removed from an aquifer at a greater rate than the sustainable recharge. Removal of water from the pore spaces may cause permanent compaction (subsidence) that cannot be reversed. Human consumption and use at sustainable levels primarily uses renewable resources versus non-renewable resources.
Renewable resources may also include goods commodities such as wood, paper and leather.
Gasoline, coal, natural gas, diesel and other commodities derived from fossil fuels are non-renewable. Some commodities, like plastics and diesel, are mostly made from fossil fuel but ways have been developed for biodegradable plastic and biodiesel made from renewable resources such as corn, soybeans and canola. Unlike fossil fuels, a renewable resource can have a sustainable yield.
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[edit] Types of renewable resources
[edit] Solar power
Solar power is the technology of obtaining usable energy from the light of the sun. Solar energy has been used in many traditional technologies for centuries and has come into widespread use where other power supplies are absent, such as in remote locations and in space. Solar energy is currently used in a number of applications:
- Heat (hot water, building heat, cooking)
- Electricity generation (photovoltaics, heat engines)
- Desalination of seawater.
- Light
[edit] Wind power
See main article Wind power
Wind power is the conversion of wind energy into more useful forms, usually electricity using wind turbines. In 2005, worldwide capacity of wind-powered generators was 58,982 megawatts; although it currently produces less than 1% of world-wide electricity use, it accounts for approximately 23% of electricity use in Denmark, 9% in Spain, and 6% in Germany. Globally, wind power generation more than quadrupled between 1999 and 2005.
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
[edit] Hydropower
See main article Hydropower
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 locate 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 metre) 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.
