Non - Renewable Resources

A non-renewable resource is a natural resource which cannot be produced, grown, generated, or used on a scale which can sustain its consumption rate. These resources often exist in a fixed amount, or are consumed much faster than nature can create them. Fossil fuels (such as coal, petroleumand natural gas) and nuclear power (uranium) are examples. In contrast, resources such as timber (when harvested sustainably) or metals (which can berecycled) are considered renewable resources.^[1]

Fossil fuel

A temporary oil drilling rig in Western Australia

Further information: Oil depletion

Natural resources such as coal, petroleum, oil and natural gas take thousands of years to form naturally and cannot be replaced as fast as they are being consumed. Eventually natural resources will become too costly to harvest and humanity will need to find other sources of energy. At present, the main energy sources used by humans are non-renewable as they are cheap to produce. Natural resources, called renewable resources, are replaced by natural processes given a reasonable amount of time. Soil, water, forests, plants, and animals are all renewable resources as long as they are properly conserved. Solar, wind, wave, and geothermal energies are based on renewable resources. Renewable resources such as the movement of water (hydropower, including tidal power;ocean surface waves used for wave power), wind (used for wind power), geothermal heat (used for geothermal power); and radiant energy (used for solar power) are practically infinite and cannot be depleted, unlike their non-renewable counterparts, which are likely to run out if not used wisely. Still, these technologies are not fully utilized but are still being researched.

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Economic models

Hotelling's rule is a 1931 economic model of non-renewable resource management by Harold Hotelling. It shows that efficient exploitation of a nonrenewable and nonaugmentable resource would, under otherwise stable economic conditions, lead to a depletion of the resource. The rule states that this would lead to a net price or "Hotelling rent" for it that rose annually at a rate equal to the rate of interest, reflecting the increasing scarcity of the resources. The Hartwick's rule provides an important result about the sustainability of welfare in an economy that uses non-renewable resources.

The Global Change

There are three types of resources in the world: renewable, non-renewable, and perpetual.  Perpetual resources are not affected by human use of them.  Examples are sunlight and wind.

Renewable resources are those that are replenished through biogeochemical and physical cycles.  By contrast, non-renewable resources do not replenish themselves, or, as in the case of fossil fuels, do so only at a very slow rate.

A Forest.  Photo Credit: ClickART Image Pak.

Renewable resources are seldom perfectly renewable.  If their levels are heavily decreased, they may not be able to completely replenish themselves.  For example, if a species is nearly eradicated, it may not be able to avoid extinction.

Renewable resources can also be lost through pollution.  Though water renews itself, if it is polluted, it is no longer useful for human use.  Urban sprawl, cultivation, irrigation, grazing, deforestation, fishing, hunting, and habitat destruction can all be causes of the destruction of an otherwise renewable resource.

There are both organic and inorganic types of renewable resources.  Examples of renewable organic substances include plant and animal species.  Inorganic examples include water and certain gases like oxygen.

During different periods of time, different things are thought of as resources.  As the usefulness of certain resources like wind have varied, their classification has changed too.

There have been numerous efforts to prevent the mistakes that lead to the depletion of renewable resources.  Despite this, destruction of renewable resources often proves to be profitable, and happens as a result.

Renewable Resources

A natural resource is a renewable resource if it is replaced by natural processes at a rate comparable or faster than its rate of consumption by humans. Solar radiation, tides, winds and hydroelectricity are in no danger of a lack of long-term availability. Renewable resources may also meancommodities such as wood, paper, and leather, if harvesting is performed in a sustainable manner.

Some natural renewable resources such as geothermal power, fresh water, timber, and biomass must be carefully managed to avoid exceeding the world's capacity to replenish them. A life cycle assessment provides a systematic means of evaluating renewability.

The term has a connotation of sustainability of the natural environment. Gasoline, coal, natural gas, diesel, and other commodities derived fromfossil fuels are non-renewable. Unlike fossil fuels, a renewable resource can have a sustainable yield.

Renewable energy

A wind farm in Spain.

Renewable energy
Biofuel Biomass Geothermal Hydroelectricity Solar energy Tidal power Wave power Wind power
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Main article: Renewable energy

Solar energy is the energy derived directly from the Sun. Along with nuclear energy, it is the most abundant source of energy on Earth. The fastest growing type of alternative energy^[1], increasing at 50 percent a year, is the photovoltaic cell, which converts sunlight directly into electricity.^[2] The Sun yearly delivers more than 10,000 times the energy that humans currently use.^[3]

Wind power is derived from uneven heating of the Earth's surface from the Sun and the warm core. 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.

Hydropower is energy derived from the movement of water in rivers and oceans (or other energy differentials), can likewise be used to generate electricity using turbines, or can be used mechanically to do useful work. It is a very common resource.

Geothermal power directly harnesses the natural flow of heat from the ground. The available energy from natural decay of radioactive elements in the Earth's crust and mantle is approximately equal to that of incoming solar energy.

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.

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Renewable materials

Further information: bioplastics and bioasphalt

Total solar (left), wind, hydropower and geothermal energy resources compared to global energy consumption (lower right).

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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 forestry techniques.

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Water

Further information: Water resources

Water can be considered a renewable material (also non-renewable) 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 sustainablerecharge. Removal of water from the pore spaces may cause permanent compaction (subsidence) that cannot be renewed.

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See also

	Environment portal
	Ecology portal
	Earth sciences portal
	Sustainable development portal
	Energy portal

• Conservation movement
• Ecology
• Environmentalism
• Environmental protection
• Global warming
• Habitat conservation
• Natural environment
• Natural capital
• Natural resource
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• Scarcity
• Zero carbon city