In fast-reaction nuclear power generation breeder reactors , high-velocity neutrons cause the fissions, using plutonium or uranium Breeder reactors produce more fuel enriched uranium and plutonium than they consume.
Thus, fast-reaction nuclear power fuel is considered renewable and sustainable. Nuclear power plants do not release carbon dioxide a contributor to global climate change or sulfur dioxide a contributor to acid rain. One obstacle to nuclear fission power is that radioactive nuclear waste is generated. High-level radioactive waste—the fission products in the used fuel rods—will be dangerous for the next to 1, years. There is no known way to speed the removal of radioactivity from waste.
Spent fuel rods are first cooled in large tanks, then encapsulated in ceramic or glass containers. These containers are then placed in stainless steel containers and stored.
Very little high-level waste is made by a reactor in a year—enough to occupy a volume of about half a cubic yard. Fossil fuels—including coal, oil, and natural gas—are sources of energy that humans have taken advantage of over thousands of years.
These were created by the decomposition of primitive organisms, buried in sand and mud, and compressed under the weight of accumulating layers. Over millions of years, temperatures and pressures changed the organic matter into coal, oil, and gas. Deposits of these resources are now found below ground in many areas of the world. Combusting fossil fuels with oxygen releases water, carbon dioxide, and other substances into the environment.
Uranium is also abundant, and technologies exist which can extend its use fold if demand requires it. World mine production is about 60, tonnes per year, but a lot of the market is being supplied from secondary sources such as stockpiles, including material from dismantled nuclear weapons.
Practically all of it is used for electricity. World resources of coal are, in theory, large enough to produce the electricity we shall need for more than a hundred years. However, it is likely that more and more of the coal mined in the future will be converted into the more valuable liquid fuels rather than being available for electricity generation.
There are also environmental and other problems associated with the increased mining and burning of coal see Uranium, Electricity and Climate Change in this series. A one million kilowatt 1, MWe coal-fired power station consumes about 3. This requires the mining of over tonnes of natural uranium which may be recovered from, say, over 20, tonnes of typical uranium ore. The enormous difference in the quantities of fuel used also directly affects the quantities of waste that remain after the electricity has been generated.
The 27 tonnes or so of used fuel taken each year from a MWe nuclear power station is highly radioactive and gives off a lot of heat. However, the small quantity makes it readily manageable. Even where the used fuel is not reprocessed, the yearly amount of 27 tonnes is modest compared with the quantities of waste from a similar sized coal-fired power station. Its safe isolation in both storage and transport is easily achieved.
See also The Nuclear Fuel Cycle. The 1, MWe coal-fired power station produces about 7 million tonnes of carbon dioxide each year, plus perhaps , tonnes of sulfur dioxide which in many cases remains a major source of atmospheric pollution. Other waste products from the burning of coal include large quantities of fly ash typically , tonnes per year , containing toxic metals and other unpleasant materials, as well as naturally-occurring radioactive substances.
If not fully contained, these routine wastes can cause environmental and health damage even at great distances from the site of the power station. For example, acid rain caused by the release of sulfur dioxide has crossed national boundaries and caused severe damage to lakes, rivers and forests in Canada, Scandinavia and elsewhere.
Any means of producing electricity involves some wastes and environmental hazard. The nuclear industry is unique in that it is the only energy-producing industry that takes full responsibility for the management and disposal of all its wastes and meets the full cost of doing so.
Nuclear energy today saves the emission of about 2. The difference in fuel requirements between coal fired and nuclear power stations also affects their economics. The cost of fuel for a nuclear power station is very much less than for an equivalent coal fired power station, usually sufficient to offset the much higher capital cost of constructing a nuclear plant. Consequently, in practical terms, electricity from nuclear reactors in many regions is competitive with electricity produced from coal, even after providing for management and disposal of radioactive wastes and the decommissioning of reactors.
As gas prices rise and coal faces the prospect of economic constraints on its emissions, nuclear energy looks increasingly attractive. Allied to this is the question of energy security. Many countries import most of their energy, so there is a great advantage if a couple of years' supply of fuel for electricity can be stored easily and economically.
For most countries the questions that need to be answered are: What are our likely electricity requirements? What forms of generation are available to us? Which combination will affordably provide our needs with maximum technical and political reliability, and the least harm to our population and environment?
In mid , there are 30 countries of varying size, political persuasion and degree of industrial development, which include nuclear power in their energy mix and are operating nuclear reactors. About No country would want to be too dependent on a single energy source. For many it is therefore not a question of coal or nuclear for their main supply of electricity, but a combination of both, with as much help as possible from renewable sources, and back-up from gas. With global climate change as a high-profile concern, nuclear power is increasingly seen as an indispensable part of the mix.
Energy for the World - Why Uranium? December Introduction About half a million years ago, human beings learned to make fire. Living standards and populations Energy, 'the ability to do work' utilising the forces of nature or the composition of dead organic material, is essential for meeting basic human needs, extending life expectancy, and providing an acceptable living standard. Primary and Secondary Energy Energy can be considered in two categories - primary and secondary.
Primary energy is energy in the form of natural resources, such as wood, coal, oil, natural gas, natural uranium, wind, hydro power, and sunlight. Source: ORNL. Renewable literally means 'to make new again'. Any resource that naturally replenishes with time, like the creation of wind or the growth of biological organisms for biomass or biofuels, is certainly renewable. Renewable energy means that the energy humans extract from nature will generally replace itself. On the other hand, a sustainable energy source can be maintained for a definable period of time, one whose total amount will last for the period of human history that needs it, at the rate it is being used or expected to be used.
It may or may not be renewed at some rate. Human energy use is dominated by a small list of primary energy types, of which the following sources are considered to be renewable: Solar power , Wind power , Hydropower , Tidal power and Geothermal energy. Energy sources are considered non-renewable if they take a very long time to be created, like fossil fuels , or if their creation happened long ago and is not likely to happen again, like uranium.
However, we are not running out of coal , oil or natural gas anytime soon. Thanks to fracking , our oil and natural gas reserves keep growing. What was thought to be global gas reserves at the time went from 60, Mtoe in to , in Natural gas is not renewable but current technology allows us to access such a staggering amount, that it may seem infinite by past standards.
And future technologies will extract even more. Keeping humans from using so much accessible fossil fuel just to protect the environment will be very, very difficult. But even a renewable energy resource becomes unsustainable whenever it's used faster than it regenerates. This is often seen for geothermal energy, where the heat is not renewed fast enough by the hot rocks and the temperature at the inlet decreases below the point that produces steam.
Conversely, a non-renewable resource can be sustainable if it's used at a slow enough rate that supplies last for thousands of years, and the environmental impacts don't cause huge problems. This is most obvious with respect to nuclear power.
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