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
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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.
[edit]Renewable materials
Further information: bioplastics and bioasphalt
[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 forestry techniques.
[edit]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.
