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10 May 2009
drive for renewable energy in the form of windpower, marine
power and the like, is driven by a belief that man-made
greenhouse gases will cause dangerous global warming and that
large-scale adoption of these technologies will “fight
climate change”. To this end, thousands of MW of heavily
subsidized wind power capacity are being added worldwide each
New Zealand we are told that windpower is economic compared to
alternatives, that the unpredictable short term fluctuations
can easily be covered by our “abundant hydropower” and it
helps conserve hydropower storage. Therefore, we are told, we
should happily accept destroying iconic landscapes and
seriously upsetting people who live nearby.
to conventional power generation, wind has a low capacity
factor (the ratio between the average output and the maximum
output). Capacity factors of overseas wind farms vary from 18
- 30% while 37 -
40% is typical in New Zealand.
truth is, as I will show, that windpower is expensive compared
to alternatives, hydropower schemes have no spare capacity to
back up windpower in a critical dry year and wind power output
is lowest in the late summer and autumn when we need it most.
windpower adds a new source of major fluctuations to power
systems that are, anyway, inherently unstable. Constant
adjustment is needed to ensure that the total generation in a
power system matches the normal fluctuations in load –
seldom above 50 MW - on a minute by minute basis.
If the fluctuations are excessive, the lights go out.
With about 1000 MW of windpower on the system we are
likely to see swings of 500 MW in a few minutes.
The system operator will find it very difficult – and
expensive – to find generating plant that can match these
swings. The cost will be
passed on to the consumers.
is seasonal. I recently analysed the output of wind farms in
New Zealand since 2000.
I found that the output was down 9% during the critical late
summer – autumn period - when the hydro lakes are at their
lowest levels - and at a maximum in the springtime when it is
raining and the snow is melting. So a large amount of backup
from new gas turbine stations will be needed.
The cost will be
passed on to the consumers.
have calculated the cost of power generated by new wind farms
such as Makara in Wellington which cost $440 million for 143
MW ($3100/kW), to be about 12 c/kWh at the station gate.
Geothermal power costs about 8 cents.
Generation from hydropower, gas or coal costs 8 – 10
cents. When the nuclear
industry begins to mass produce new, small, sealed, inherently
safe, high-temperature gas reactors, or advanced versions of
existing reactors, the costs are likely to be similar.
is often claimed that power systems like ours could run
entirely from windpower and other new renewable energy
fact is that these technologies cannot provide a reliable
supply unless they are associated with a low cost and
efficient energy storage for periods of days, weeks and
months. The best
available technology is hydro pumped storage which, in
general, can store energy for only about 10 hours operation.
Pumped storage is neither efficient nor cheap.
illustrate the problems and costs I carried out a “clean
sheet” study of a notional power system with a peak demand
of 5,000 MW at a capacity factor of 60% giving an annual
energy demand of about 26,000 GWh pa.
(The New Zealand system is 7000 MW and 43,000 GWh.)
calculated the total cost of supplying the whole system from
base load geothermal power combined with hydro pumped storage
to meet daily load swings and compared it with windpower
backed up by large scale pumped storage that would cope with
the rapid swings in output of the wind farms and also store
large quantities of energy in the springtime for use in the
calculations showed that the geothermal option needed 4000 MW
of geothermal plant and 2000 MW of pumped storage.
a capacity factor of 37%, the windpower option needed 9,500 MW
of windpower plus 6,000 MW of pumped storage (a total of
15,500 MW) to supply the 10,000 MW of load.
At first sight, this figure looks ridiculous but the
fact is that the wind farms must generate sufficient power to
supply the load and to meet the 25% losses involved in pumped
storage. Also the pumped storage schemes have be able to
absorb all the windpower generated when the system load was
low and the wind output was high.
was costed at 4500/kW which is the generally accepted figure
for stations in New Zealand.
Based on investigations I have carried out into the
cost of recent wind farms worldwide and confirmed by the
published cost of Makara windfarm
and the estimated cost of the Hayes windfarm, wind
power was costed at $3100 per kW.
I used a cost of $2000 per kW for the pumped storage
schemes which, from my background in hydropower, is on the low
side for schemes that store energy in the springtime to use in
winter. For the purpose of the study I ignored that fact that,
worldwide, suitable sites are as scarce as hen’s teeth.
made reasonable allowances for the cost of transmission. I
made my own estimates for the costs of operation, maintenance
and steam supply for the geothermal power plant and took the
costs for windpower from
a recent Finnish report.
calculations showed that the geothermal powered system would
cost about $24 billion and would supply power for about
equivalent wind powered system would cost about $50 billion
and would supply power for about 21 cents/kWh.
More than twice the cost.
conclusion is that wind power is very expensive and large
scale power supply from windpower (and other new renewable
technologies), 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.
comparison was for an extreme situation where all the
electricity comes from windpower.
In a real system, the cost of wind would vary from
12c/kWh for a very small percentage
of wind power and would increase quite rapidly to a plateau
cost of about 20 cents as the percentage of wind power
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. The
fact that New Zealand has an unusually good wind resource,
simply means that the burden on the consumer is not as large
as it is in other countries.
believe that, given the high cost and operational problems
of wind power, no responsible Board of Directors of a
state-owned or private company could – or should - agree to
“investing” in windpower.
There are better and cheaper alternatives.
world has been cooling since 2002.
If this trend continues or deepens, there will be a
worldwide $500bn crash in the value of subsidized renewable
energy projects and carbon trading.
Let New Zealand lead the world by studying the evidence
and evaluating the risks!
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