1.Efficiency of Wind Turbines
It is sometimes alleged that wind turbines are inefficient and
'only work 30% of the time'. This figure is based on the 'load
factor' for onshore wind farms, but is erroneously used to imply
wind power is inefficient. This is wrong - load factor and
efficiency are not the same; in fact, conventional power stations
in the UK run with an average load factor of 50-55%, but these are
not described as running "half the time". The 'load factor', is the
average power output (i.e. actual output measured over a period of
time, usually measured in hours) divided by what could have been
produced had the generator run continuously at peak capacity over
the same period. It is from this calculation that the 30% figure
for wind turbines is drawn, but load factor should not be confused
with efficiency; that is to say, this does not mean wind turbines
are 70% inefficient, or that they only run for seven hours every
day.Wind farms actually generate electricity around 80-85% of the
time, and power is converted to electricity very efficiently, with
none of the thermal waste inherent in fossil fuel plants. So, wind
power is an efficient way to generate electricity, employing a free
energy source that is also renewable.
References:
Common
Concerns about Wind Power - Centre for Sustainable Energy May
2011 (last accessed 30/10/2012)
2. Wind turbines, Costs and Subsidies
It is often argued by organised groups opposed to wind energy,
and repeated in the national press, that wind power is both
expensive and is heavily subsidised by the taxpayer. In fact,
onshore wind is already cost-competitive with conventional
large-scale generation. And while it is true that all forms of
renewable energy generation benefit from specific government
support, it must be recognised that all forms of large-scale
generation - whether low carbon or conventional - receive some kind
of state support (in the form of subsidies, capital grants and
allowances, etc). It is the case that, so long as the
'externalities' related to power generation from conventional fuel
sources (from the plant itself or from the fuel supply chain
impacts) are not included in the cost of those activities,
government support will be needed to incentivise the low carbon but
capital intensive forms of generation.
The evidence demonstrates that wind energy is already cost
competitive with conventional electricity generation over the
lifetime of the plant. Furthermore, there are no fuel costs
associated with operating a wind farm, unlike fossil fuel plants.
Fossil fuel prices are set to increase now that less accessible
fuel reserves need to be extracted to meet global demand. This
means the relative price of wind energy is likely to become even
cheaper. Much of the environmental and social cost of conventional
fuels is not reflected in the cost of generating electricity from
conventional large scale plant, and effectively amount to
additional public subsidies. Internalising these costs completely
would further increase the costs energy generated from conventional
fuel sources.
References:
Common
Concerns about Wind Power - Centre for Sustainable Energy May
2011 ( last accessed 27/9/2012)
3. Wind Turbines and Energy Payback Times
Concerns about the amount of energy (and subsequent CO2
emissions) involved in the manufacture, construction and operation
of a wind farm are often voiced as an argument against its
installation. It is true, of course, that some energy will be
required over the whole life cycle of a wind farm. This includes
the manufacture of materials; the transportation of parts to the
site; construction of the turbines and supporting infrastructure
like foundations; site operations and maintenance; and, finally, in
decommissioning the site. However, this is true of all forms of
energy generation.
The issue, therefore, lies in whether the plant will generate
sufficient useable energy over its lifetime to justify the energy
involved in its installation. In the case of wind farms, all the
evidence suggests that this is the case: the average wind farm is
expected to generate at least 20-25 times the energy required in
its manufacture and installation over its lifetime, and the average
energy payback time for a wind farm is in the region of 3-6 months.
These figures compare well with other forms of power generation
systems. For example, coal offers a lower energy return on
investment of around 8 and nuclear around 9.
References:
Common
Concerns about Wind Power - Centre for Sustainable Energy May
2011 ( last accessed 27/9/2012)