Modern power systems are huge, complex and inherently unstable. Few people understand the problems of ensuring that the total generation in a power system matches the fluctuations in load on a minute by minute basis. If the fluctuations are excessive, the lights go out. Large scale windpower adds to the normal fluctuations.
Compared to conventional power generation, wind has a low capacity factor (the ratio between the average generation and the maximum generation) and an output that is unpredictable. Capacity factors vary from 18 – 20% in Germany and are about 25% in many countries.
Because windpower is unpredictable and seasonal, large-scale windpower needs a technology that will provide low cost and efficient energy storage for periods of days, weeks and months. Without that, it cannot provide the economic and reliable supply we need.
A recent report commissioned by Greenpeace and the European Renewable Energy Council (Europe’s largest renewable energy trading association) claimed that it was possible to replace all United States power generation from coal, nuclear and oil-fired power stations with low cost renewable energy. Most of this renewable energy – wind, plus some solar and ocean – would be intermittent and seasonal.
The authors of the study ignored:
• the huge – and unsolved – problem of storing the energy when it is available so that it can be used when it is needed;
• the very real problems of coping with the unpredictable and rapidly fluctuating output of the windfarms;
• the very high real cost of windpower;
• the cost and problems of the large-scale long distance power transmission that would be needed.
To illustrate these problems I carried out a “clean sheet” study of a notional power system with a peak demand of 10,000 MW at a capacity factor of 60% giving an annual energy demand of about 55,000 GWh pa. I calculated the total cost of supplying this system from nuclear power backed up by hydro pumped storage and compared it with a combination of windpower and large scale pumped storage.
I chose nuclear power because it is “carbon free”, has low fuel costs and the cost is much same all over the world. As the nuclear power option could supply all the load all the time, the same obligation was imposed on the wind powered option.
My calculations showed that the nuclear option needed 7700 MW of nuclear and 3500 MW of pumped storage.
Assuming a capacity factor of 25%, the windpower option needed 31,000 MW of windpower plus 10,000 MW of pumped storage (a total of 51,000 MW) to supply the 10,000 MW of load. At first sight, this looks ridiculous. It isn’t because:
a) the wind farms must generate sufficient energy to supply the load and to meet the 25% losses involved in pumped storage;
b) the pumped storage schemes must be able to absorb all the windpower generated when the system load is low and the wind output is high.
For the purpose of the exercise I chose to ignore the fact that, worldwide there are very suitable sites for these huge pumped storage stations. Note that there is no alternative storage technology available or under development.
I calculated the cost of generation from the two systems. I used the cost of $US4000 per kW for the nuclear power stations quoted in a recent Finnish report. Wind power was costed at $US2250 per kW. This is based on investigations I have carried out into the cost of recent wind farms worldwide. I used a cost of $US1500 per kW for the pumped storage schemes which, from my background in hydropower, is reasonable for schemes with 6 – 10 hours storage.
I made reasonable allowances for the cost of transmission. The costs of operation, maintenance and fuel for a nuclear power plant and windpower was taken from the Finnish report.
My calculations showed that the nuclear powered system would have a total installed capacity of 11,900 MW, would cost about $US46 billion and would supply power for about 9c/kWh. The equivalent wind powered system would have an installed capacity of 51,000 MW, a total cost of $US128 billion and would supply power for about 26c/kWh.
The conclusion is that, on an “apples for apples” comparison, the cost to the consumer of large scale windpower is two to three times as much as nuclear power. Putting it another way, if nuclear power cost $15,000/kW it would still be preferable to wind power!
If the same exercise had been carried out for hydropower stations with seasonal storage or coal-fired power stations instead of nuclear, the result would have been much the same.
The conclusion is:
a) wind power is very expensive;
b) large scale windpower cannot be contemplated until an efficient, low-cost method of storing large amounts of electricity for long periods is discovered. I am not aware of any technology that comes anywhere near to meeting this requirement.
Windpower exists worldwide because of grants, tax breaks and massive subsidies and because, consumers, taxpayers and ratepayers, not the generators, pay for the cost of transmission and backup power stations.
If, as strongly indicated by the current extended sunspot cycle, the world continues to cool, it will not be long before the public realize that that manmade global warming is a myth. When that happens the $750 bn invested worldwide in heavily subsidized renewable energy and carbon trading will rapidly become “sub-prime”. That, not manmade global warming, is the big risk of continuing to subsidise and promote an uneconomic and unreliable source of power.