Nuclear Power

Sustainable energy sources that aren't renewable are those whose stock is not replenished, but for which the presently available stocks are expected to last for as long as human civilization cares to use them.
These energy sources are derived from nuclear energy, as other forms of stored energy found on Earth do not have sufficient energy density to supply humanity indefinitely.
Fission power uses the nuclear fission of heavy elements to release energy that drives a heat engine. Primary challenges with the use of fission power are the production of small quantities of highly-radioactive waste in the form of spent fuel, larger quantities of less-radioactive waste in the form of activated structural material, and (for use as a long-term power source) the need to perform intensive processing of highly-radioactive fuel bundles, both to reclaim unused fuel in spent fuel rods, and to reclaim plutonium 239 and uranium 233 that have been bred from uranium 238 and thorium 232, respectively.
Fusion power uses the nuclear fusion of isotopes of hydrogen to release energy that drives a heat engine. Primary challenges with the use of fusion power are that the technology required to build a useful fusion power plant are still under development, and that substantial quantities of radioactive waste in the form of activated structural material is produced.
Fission power's long-term sustainability depends on the amount of uranium and thorium that is available to be mined. Estimates for fuel reserves vary widely, but if breeder reactors and fuel reprocessing are assumed, tend to be tens of thousands of years or longer (uranium is approximately as common in Earth's crust as tin or zinc (2 ppm), and thorium as common as lead (6 ppm)).
Fusion power's long-term sustainability depends on the amount of lithium that is available to be mined (for deuterium-tritium fusion), or the amount of deuterium available in seawater (for deuterium-deuterium fusion). Lithium is a reasonably common component of Earth's crust, being about 10 times as common as thorium (65 ppm). Deuterium (a hydrogen isotope) occurs wherever hydrogen is found (principally in water), at about 150 ppm. As it can be extracted easily from seawater, economically viable reserves of deuterium are for practical purposes unlimited.


Technical sustainability of nuclear power
Discussions are re-emerging on proper classification of nuclear energy under such umbrella terms as "renewable" and "sustainable" These attributes bring moral gains or eligibility for development aid under various jurisdictions.
The primary argument in favor of "renewable" status is the relatively inexhaustible supply of fuel available (uranium and thorium for fission or hydrogen for fusion). See also: Renewable energy, Nuclear power section.
Proponents, such as environmentalists James Lovelock, Patrick Moore (Greenpeace co-founder), Stewart Brand (creator of The Whole Earth Catalog), and Norris McDonald (president of the AAEA), also claim that nuclear power is at least as environmentally friendly as traditional sources of renewable energy, making it the best future solution to global warming and the world's growing need for energy. They note that nuclear power plants produce little carbon dioxide emissions and claim that the radioactive waste produced is minimal and well-contained, especially compared to fossil fuels. [3]
In 2001, professors Jan Willem Storm van Leeuwen and Philip Smith released a study which argued that, though nuclear plants don't produce any CO2 directly, the energy required for the rest of the nuclear fuel cycle (uranium mining, enrichment, transportation) and power plant life cycle (construction, maintenance, decommissioning) leads to significant carbon dioxide emissions, especially as usage of lower-grade uranium becomes necessary.[4] In 2000, however, Frans H. Koch of the International Energy Agency reported that, although it is correct that the nuclear life cycle produces greenhouse gases, these emissions are actually less than the life cycle emissions of other renewables, like solar and wind, and drastically less than fossil fuels.[5]

Political sustainability of nuclear power
The use of nuclear power is political and controversial because of the problem of storing radioactive waste for indefinite periods, the potential for severe radioactive contamination by accident or sabotage, and the possibility that its use could in some countries lead to the proliferation of nuclear weapons.

Serious nuclear accidents which have occurred include the 1986 Chernobyl disaster, the 1979 Three Mile Island accident, the 1957 Windscale fire, and the 1957 Mayak accident. The nuclear power industry went into a period of decline for some years following the Chernobyl and Three Mile Island accidents (see Nuclear power controversy).
Some critics of nuclear energy argue that deployment of nuclear reactors in many countries would accelerate the proliferation of nuclear weapons technology that has many links with civilian use of nuclear materials. Some nuclear reactors (especially heavy water moderated reactors) create the materials necessary for these weapons.
The issue of fuel reprocessing and/or long-term repository of nuclear waste materials also remains contentious. Very few countries have developed waste depositories for high-level radioactive waste (see: Yucca Mountain Repository USA; Gorleben Germany; Forsmark, Sweden).
Due to opposition to nuclear power many countries (Austria, Italy, Sweden, Germany) have effectively banned further development of nuclear energy showing a clear lack of political sustainability under present conditions. Some other countries, such as Australia, have never built a nuclear power station

From wikipedia