Renewable resources include knowledge, people, energy from wind, solar energy, and burning of biomass. Renewable materials include wood, water, air, wax, paper, cardboard and leather. Some people do not count hardwoods as renewable because of the length of time they take to replenish. Some materials are relatively easy to recycle, such as steel, aluminum, copper and glass. Many persons consider these renewable as well.
All of these can be recycled or produced without the use of nonrenewable resources. Aluminum and steel are renewable because they are easy to reclaim from scrap, and both can be produced from abundant minerals. Copper is easy to reclaim from scrap, and therefore is renewable to a lesser extent.
Plastics, gasoline, coal, natural gas and other items produced from fossil fuels are nonrenewable, because the resource is depleted, and can only be used once.
There have been experiments in which steam and high heats were applied to reduce polymers back to monomers. These monomers could then be chemically purified, and reploymerized into new virgin plastic feedstocks. At this time, recycled monomers are uneconomic, because the resulting feedstock is more expensive than virgin feedstock from petrochemicals. However, the processes exist, and there is no reason to believe that the world will run short of plastic.
Gasoline can be produced from non-fossil fuel sources although this has only been used on a small scale because of high costs. Bio-diesel can be used to stretch or replace diesel fuel.
Authorities debate whether nuclear power is sustainable. On the one side, with breeder reactors, fuel reprocessing, and the use of the Uranium in seawater (a known technique), advocates produce numbers indicating that the entire industrial world can powered until the Sun expands to consume the Earth. Antagonists argue that nuclear wastes are too hazardous to produce. Antagonists concede that nuclear wastes have very small volumes compared to the wastes of a chemical power plant. Advocates of nuclear power admit that the wastes are very hazardous. Antagonists counter-claim that uranium supplies are too limited, and too dangerous to mine because of the exposures of miners to Radon.
See also sustainable design, and autonomous building.
A related article (the logical inverse) is waste management