Energy Recovery Time For Nuclear Power Plants
Stichting GroenLinks in the European Union/The Group of the Greens/European Free Alliance 1oct00
It takes energy to mine uranium ore. The lower the uranium content, the more energy-intensive the extraction process. When the uranium content is low, the nuclear energy process chain uses more energy than it generates in electricity. Most of the uranium ore extracted today has a uranium content of between 1 and 10 percent, which makes extraction cost effective. However, if nuclear energy were to gain momentum, a point would come when uranium ore extraction would no longer be cost-effective. The 'energy recovery time' (i.e. the time the nuclear power station has to have been operational before all the energy consumed in the chain has been earned back and the power station begins to produce net energy) is highly dependent on the uranium content of the ores, and is about 10 years for uranium-rich ores (10 per cent) and 18 years for uranium-poor ores (0.05 per cent). It is difficult to compare this figure with the energy recovery time for fossil fuel-powered power stations: note that a fossil fuel power station only has to recover the electricity used for construction and other constituent processes in the chain. In such a case, the recovery time for power stations fired by gas and oil is 0.09 of a full-load year (approximately 0.13 of a calendar year) and for coal-fired power stations, 0.15 of a full-load year (approximately 0.21 of a calendar year).
Energy recovery time for a nuclear power station.
The use of poorer uranium ore (from 10 till 1 percent) influences the net energy production (E) and enlarges the energy recovery time (L).
Nuclear power stations, wind turbines and PV systems only generate electricity (unlike modern gas-fired power stations, which also generate and supply heat). All the energy used in the chain is recovered in the form of electricity, which increases the recovery time considerably. To enable a more accurate comparison of power stations fired by fossil and other fuels to be made, we have assumed that the fossil-fired power stations must recover the energy used in their construction entirely in the form of electricity. This results in a recovery time of 0.7 full-load years for gas or oil-fired power stations, which is approximately 1 calendar year. Coal-fired power stations have a longer recovery time.
Wind 0.62-0.9 years Gas and Oil 1 year PV (photovoltaic) System 1.5-3 years Nuclear Power Station 10-18 years
Improvements in conversion yields and production methods will help to reduce the recovery time for PV (photovoltaic) systems in the future. PV technology is at the peak of development and at the moment we are in the sharply rising section of the learning curve, which means that prices are falling significantly as more PV capacity is built. It is conceivable that the recovery time for PV will drop to less than 1 year as technical progress continues. Nuclear energy, on the other hand, is a mature technology: the price of nuclear power will not decrease as more nuclear power stations are built. In the past there were even cost hikes of approximately 14 per cent a year until the mid-1980s. After that time, no new nuclear power stations were ordered in the OECD countries, giving no opportunity for further price rises.
Clearly, the recovery time for nuclear power stations is much longer than that for all other types of power stations and will never decrease. On the other hand, the recovery time for PV systems in particular is certain to decrease.
France is the world champion when it comes to the share of the nation's electricity that is produced by nuclear energy. Nearly 76 per cent of the electricity generated in France is produced by nuclear power stations. Together, the country's 59 nuclear reactors swallow up the output of 4.5 reactors a year. The sector consumes nearly 8 per cent of its own production. Thanks to a mammoth nuclear construction programme, France has considerable ouercapacity, which it disposes of by trying to get French households to use electric heating and by dumping cheap surplus electricity in foreign countries (e.g. the Netherlands). Nevertheless, the tide appears to be turning. No more nuclear reactors are being built, breeder technology is being mothballed and (small-scale) combined heat and power production (CHP) is on the rise.
GOOD THINGS COME IN SMALL PACKAGES
The cost of electricity depends entirely or largely on the size of the power supply station. Between 1960 and 1980, the ideal size for a station rose from 400 to 1000 MW. It was no coincidence that this was the size of a nuclear power station. These days, 5 MW is regarded as the ideal size, because small-scale power generation permits a flexible response to energy demand. Small-scale units such as wind turbines, photovoltaic cells, fuel cells and biogasification plants are the future. Nuclear power stations are many times too big.
Mindfully.org note: This file is excerpted from a page explaining some of the differences between gas, oil, photovoltaic and nuclear power generation. The chart above was redrawn from the much smaller one on that page. [Link to complete page]
source: http://www.antenna.nl/wise/537/gl/clean.html 12feb2005