FAQs
What happens when the wind stops blowing?
Wind turbines only operate when the wind blows. At the moment,
when the wind stops blowing, electricity continues to be
provided by other forms of generation, such as gas or hydro.
But New Zealand is one of the windiest countries in the
world, so we have a massive resource waiting to be used. And
in the future, all our electricity could come from a mix of
complementary renewable sources - balancing wind power
with hydro, solar, geothermal, biomass and in the future, wave
and tidal power.
There is actually a lot of confusion about the reliability
of different sources of electricity. No power stations are
able to operate all the time without stopping. Many so-called
reliable sources such as nuclear plants suffer from unexpected
'outages' when reactors must be shut down, often at short
notice, for essential safety maintenance. Unreliability of
this kind is far harder to deal with than the intermittency
of wind power, as the amounts of electricity involved are generally
much higher. By comparison the variation in output from wind
farms distributed around the country is scarcely noticeable.
And the wind will never stop blowing everywhere in New Zealand
at once. Different overseas studies have sought to determine
the limit beyond which installing intermittent capacity (i.e.
wind generators) starts to incur significant costs in order
to maintain the stability of the electrical grid. The level
varies but is typically 15-30% of the total installed capacity.
Since New Zealand has a total installed generating capacity
of 8,412 MW this 15-30% band would be equivalent to 1,200-2,400MW
of wind turbine generators. Up to now (beginning of 2005) we
have installed about 168MW. Of course we have to find out the
maximum theoretical limit of wind energy on our grid, but it’s
still a long way to reach this limit.
It is true that we could never rely on wind turbines alone
to provide for all our electricity needs. But it is also
very important to note wind power and hydro are perfectly suited
to each other. As New Zealand generates a remarkable energy
amount from hydro dams this is very advantageous for us.
Wind and hydro are well suitable because the volume of water
flowing through hydro dams around the country can be reduced
when the wind is blowing. In effect what this means is that
the electricity generated by wind turbines can be stored as
potential energy in water in hydro dams. This 'stored' wind
energy can then be released and used to generate electricity
when the wind is not blowing.
In future, hydrogen could offer a potential way of storing
electricity from wind power. Excess wind power can be used
to produce hydrogen through electrolysis, and then hydrogen
can be turned back into electricity using a fuel cell, as
and when it is needed.
For more information look at the NZ Wind Energy Association
website
Notes:
(1) www.windenergy.org.nz/FAQ/elecsupply.htm#nowind
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