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Uranium can supply energy for the world's electricity with less greenhouse effect than virtually any other energy source.
The 'greenhouse effect' is not a new concept. In 1863 Irish-born scientist John Tyndall was writing about 'greenhouse gases' and some 30 years later Swedish scientist Svante Arrehenius made the first known attempt to calculate the impact of increased carbon dioxide in earth's atmosphere.
Today there is no question about the existence of the greenhouse effect. Without it our planet would be vastly colder (by 33°C on average), and present life forms would be very different. Water vapour is the main greenhouse gas, accounting for some three quarters of the greenhouse effect, and nothing we do is likely to change it very much.
But is human activity, particularly since the beginning of the Industrial Revolution, turning up the heat? Is it causing changes which will dramatically affect our climate and environment? A major source of greenhouse gases today is the burning of fossil fuels to provide energy, particularly electricity.
Each year well over 25 billion tonnes of carbon dioxide are put into the atmosphere by human activity. This is only about 3% of the natural flux between atmosphere and oceans or land. But its balance is critical. Carbon dioxide is responsible for over 60% of human-induced global warming.
If much of the human effect which tends to increase global warming comes from our use of energy, we need to ask:
Who Needs Energy?
Everyone. Today the world uses a great deal of energy and the usage is increasing dramatically in developing countries.
In the early 1970s a fourfold increase in the price of oil alerted the world to the need for more efficient use of energy, and more diversity of supply.
In OECD* countries the response to this, including greater use of electricity as a means of increasing efficiency, led to a levelling off in demand for primary energy. Between 1973 and 1985 primary energy demand in the OECD remained unchanged despite an increase in gross domestic product (GDP) of 33%. Since 1985 energy use has been rising again.
* Organisation for Economic Cooperation and Development
Outside the OECD countries the picture is different, and primary energy demand is increasing by about 50% each decade. Overall, world energy demand is expected to increase by more than 50% from 2005 to 2030.
Source: OECD/IEA World Energy Outlook 2004
Any attempt to understand or forecast global energy requirements must take account of population growth. At the beginning of the twentieth century, world population was about 1.5 billion. Today it is over 6 billion and growing at the rate of 90 million a year. By the year 2025 world population is expected to reach 8 billion.
Rate of population increase
Over 90% of world population growth in the foreseeable future will be in the less developed countries, which already contain 75% of the world's people. United Nations projections show most of this growth taking place in urban areas.
Even with effective energy efficiency programmes in developed countries there will be a global need for much more energy if people in the less developed countries are to improve their standards of living. A large part of this increase will be in electricity.
World electricity demand is forecast to double between 2002 and 2030. For instance, while the growth in demand for primary energy in East Asia is around 5% per year, that for electricity is 7-8% per year. In China, power generation requirements are expected to almost double in 15 years, with much of this being met by nuclear. China intends a fivefold increase in nuclear power capacity by 2020 (from 2005 level).
The Increasing Role of Electricity
Electricity is the most widely used and rapidly growing form of secondary energy supply. Its generation accounts for about 40% of total primary energy supply. It offers great flexibility of distribution and use, is relatively efficient, very safe for the consumer, and environmentally benign in end-use.
Although overall energy intensity (energy per unit of GDP) fell 25% worldwide 1971 to 1997, electricity demand increased almost threefold over this period. The share of electricity in total energy consumed will rise from 16% in 2002 to 20% in 2030.
All energy conservation scenarios assume the expanded use of electricity. The most important fuel for generating electricity is coal which provides 39% of all electricity generated. Uranium used in nuclear power stations today provides 16% of the growing total.
During the years 1990 to 2003 electricity production in the major geographic regions and the world grew as follows:
Growing Electricity Production: Billion Kilowatt Hours (TWh)
Source: OECD/IEA 2005, Energy Statistics of Non-OECD countries, 2002-2003.
In 2002 world production of electricity by the fuel used was:
This means 65% from fossil fuels, which give rise to substantial carbon dioxide emissions. In the OECD countries nuclear power contributes about 23% of total electricity.
There is more electricity generated by nuclear power today than from all sources worldwide about 40 years ago (2618 billion kWh in 2004).
Electricity and Greenhouse Gases
Every form of energy conversion, such as turning primary energy into electricity, has some environmental implications.
In recent years attention has been focused on the climate change effects of burning fossil fuels, especially coal, due to the carbon dioxide which this releases into the atmosphere.
Carbon dioxide contributes at least 60% of the human-induced increase in the greenhouse effect. Electricity generation is one of the major sources of this carbon dioxide, giving rise to about 9.5 billion tonnes per year - 40% of it, or about one quarter of the human-induced greenhouse increase.
Coal-fired electricity generation gives rise to nearly twice as much carbon dioxide as natural gas per unit of power, but hydro and nuclear do not directly contribute any. If the amount of nuclear power were doubled, emissions from electricity generation would drop by one quarter.
Conversely, there is scope for reducing coal's carbon dioxide contribution to the greenhouse effect by substituting natural gas or nuclear power, and by increasing the efficiency of coal-fired generation itself, a process which is well under way. Nuclear power is well suited to meeting the demand for continuous, reliable electricity supply on a large scale (ie base-load electricity), the major part of demand.
At the time of the oil shocks early in the 1970s, France was heavily dependent on overseas supplies of energy. Since then it has built 60 nuclear reactors in a major programme. Nuclear power now provides 78% of its electricity, it has become a major exporter of electricity (60 billion kWh per year), and it now has a high level of energy independence. Moreover the cost of electricity has declined markedly and per capita carbon dioxide emissions are half those of its neighbours. Next door, Italy is the only industrialized European country without its own nuclear power generation, but it is also the world's main electricity importer - mostly from France.
Fuel Consumed
A 1,000 megawatt electrical (MWe) coal-fired power station burning coal has a typical fuel requirement of almost 3.2 million tonnes* of black coal a year.
*assumes coal yielding 24 MJ/kg and plant operating at 80% capacity. Burning brown coal at 8.15 MJ/kg would require 9.3 million tonnes of fuel.
A nuclear power reactor of the same capacity, (after its initial fuel loading of uranium), has an annual requirement of around 27 tonnes of fuel. Producing this amount of uranium fuel requires the mining of 45-70,000 tonnes of typical Australian uranium ore, or even less Canadian ore. This yields about 200 tonnes of uranium oxide concentrate which is sold, the rest stays at the mine, as tailings. The uranium oxide is enriched to yield the 27 tonnes of actual fuel (see The Nuclear Fuel Cycle in this series).
Coal-fired power stations worldwide consume over 3200 million tonnes of coal each year to produce 38% of the electricity. This compares with about 61,000 tonnes of natural uranium (72,000 t of oxide concentrate from the mines) providing the fuel for the nuclear power stations which provide 16% of the world's electricity.
Much of the coal is used in the country in which it is mined, but often it has to be transported long distances, which requires considerable energy (and results in further greenhouse gas emissions).
By comparison, very little uranium is required to do the same job. The 1000 MWe nuclear power station requiring 27 tonnes of fresh fuel per year means an average of about 74 kg per day, which would fit in the back of a car. An equivalent sized coal-fired station needs some 8600 tonnes of coal to be delivered every day.
Wastes
Each year the 1000 MWe coal-fired power station produces about 7 million tonnes of carbon dioxide, perhaps 200,000 tonnes of sulphur dioxide (depending on the particular coal) and typically about 200,000 tonnes of solids, mostly fly ash. The ash contains several hundred tonnes of toxic heavy metals including arsenic, cadmium, lead, vanadium and mercury which remain toxic forever. If brown coal is used the carbon dioxide figure is about 9 million tonnes.
Methods exist for removing sulphur dioxide and nitrous oxide although the cost is high. Fly ash is generally captured and dumped in landfill. However there is no economically feasible way to remove or reduce carbon dioxide from the burning of coal. None of these emissions occur at a nuclear power station, where virtually all wastes are contained in the 27 tonnes or so of used fuel, and are therefore not released to the environment.
The combustion of coal may also release radioactive heavy metals (including uranium and thorium) contained in it, though these are mostly retained in the fly ash. The use of natural gas releases radioactive radon. The amount of radioactivity released is negligible relative to the natural background radiation levels, but is often greater than that from nuclear power generation.
If the electricity produced worldwide by nuclear reactors were generated instead by burning coal, an additional 2600 million tonnes of carbon dioxide would be released into the atmosphere each year. This can be compared with the target of a 5% reduction (600 million tonnes per year) in carbon dioxide emissions by the year 2010, as agreed in 1997 at Kyoto just for the developed countries.
Every 22 tonnes of uranium used avoids the emission of one million tonnes of carbon dioxide, relative to coal. When the electricity comes from coal, every kilowatt hour of it results in about a kilogram of carbon dioxide being emitted.
Borosilicate glass from the first waste vitrification plant in UK in the 1960s. This block contains material chemically identical to high-level waste from reprocessing. A piece this size would contain the total high-level waste arising from nuclear electricity generation for one person throughout a normal lifetime.
The total amount of used fuel resulting from operation of all the world's commercial nuclear power stations is about 12,000 tonnes per year. About two thirds of this is treated as waste, while the rest is reprocessed to recover useful fuel material. The reprocessing of used fuel results in only about 3% of it being high-level radioactive waste (which is then incorporated into glass), with the balance being recycled as fresh fuel.
Handling, storage and treatment of these radioactive wastes has been undertaken in many countries for several decades without incident. Nuclear power is the only energy-producing industry which takes full responsibility for all its wastes and costs this into the product.
The used nuclear fuel elements - or the separated high level wastes - are stored for up to 50 years to allow for the decay of most of the radioactivity and heat (to about 0.1% of what it was when removed from the reactor) before final disposal. Today the waste disposal issue is not a technical problem but one of public and political acceptance.
The Role of Renewables
Renewable energy sources for electricity are diverse, from solar, tidal and wave energy to hydro, geothermal and biomass-based power generation. Apart from hydro power in the few places where it is very plentiful, none of these is suitable, intrinsically or economically, for large-scale base-load power generation.
Because of their diffuse nature (making them difficult to harness efficiently) and their intermittent availability (giving rise to the need for storage or back-up from other sources), their role in meeting electricity demand on any significant scale will always be limited. A 20% contribution to grid supply is the maximum conceivable for non-hydro sources, and about half of this is likely. Renewables have most appeal where demand can accommodate small-scale, intermittent supply of electricity.
Conclusion
All of the various means of generating electricity have a role to play in meeting the rapidly increasing demand for this form of energy. Fossil fuels, particularly coal and gas, will remain important. Since reliability is the most important attribute of electricity supply, the role of non-hydro renewables is limited.
Nuclear electricity is one part of the solution of the energy equation for today and tomorrow, particularly in the light of concerns about carbon dioxide emissions. Without nuclear power the world would have to rely almost entirely on fossil fuels, especially coal, to meet demand for base-load electricity production. This has significant environmental, and particularly greenhouse gas, implications.
Nuclear power plants do not emit any carbon dioxide, nor any sulphur dioxide or nitrogen oxides. Their wastes end up as solids and, though requiring careful handling, are very much less than the wastes from burning coal.
Whenever new electricity generating capacity is required or old fossil-fuelled plants need to be replaced it is therefore sensible to consider nuclear as a serious option. Nuclear electricity has accumulated over 12,000 reactor-years of operating experience.
The continued and expanded use of nuclear power is one among a range of measures which will effectively limit future global carbon dioxide emissions. Some 35 countries have chosen nuclear power as part of their energy mix. They have over 440 power station reactors in operation and more under construction.
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