Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
6.4.7 Due to natural variations in wind speed it has been estimated that the output from a wind farm
is approximately 30% 6 of the maximum output. The energy output from the proposed wind
energy development would therefore be approximately 26.28GWh per annum based on four
2.5MW turbines. This figure is derived as follows:
10,000kW (4 x 2.5 MW turbine) x 8,760 hours/year x 0.3 (capacity factor) = 26,280,000kWh
6.4.8 Based on the 4,602kWh figure and the assumption that the wind energy development annual
output is 26.28GWh, it is estimated that the yearly output from the proposed wind energy
development will be able to provide electricity for approximately 5,710 households. In 2009,
there were approximately 23,000 households in the Clackmannanshire Council Area 7 ;
therefore the equivalent of approximately 25% of households in Clackmannanshire could have
their annual electricity consumption supplied by the proposed wind energy development. This
percentage may decrease slightly during the lifetime of the proposed wind energy development
due to predicted population growth in Scotland as a whole 8 . However, there is also the strong
possibility that domestic electricity consumption may reduce due to energy efficiency measures
that are currently being proposed the Scottish Government 9 . Although these figures are open
to variation, in principle they show that the proposed wind energy development will provide a
substantial proportion of electricity used in the local area.
Reductions in Atmospheric Emissions of CO 2
6.4.9 It is widely accepted that electricity produced from wind energy has a positive benefit with
regard to reducing CO 2 emissions. In estimating the actual saving, it is important to consider
the mix of alternative sources of electricity generation, for example coal powered and gas
powered, and there has been much debate about the amount of CO 2 emissions that could
potentially be saved as a result of switching to wind generation. In September 2008, the
Advertising Standards Authority endorsed a figure of 430gCO 2 /kWh, based on the assumption
that the energy generated by the wind turbines displaces Combined Cycle Gas Turbines and
an average mix generation (430gCO 2 /kWh). On this basis, and on the assumption that the
wind energy development annual output is 26.28GWh, a wind energy development of this
scale is expected to avoid 11,300 tonnes of CO 2 emissions per year being emitted to
atmosphere. This figure is derived as follows:
26,280,000kWh x 430gCO 2 /kWh = 11,300 tonnes CO 2
De-commissioning
6.4.10 During the de-commissioning of the proposed wind energy development the movement of
vehicles and on-site plant will generate exhaust emissions. Given the short-term nature of this
period, and the limited area affected within the application area, effects on local air quality
during the de-commissioning phases are likely to be negligible.
Carbon Payback
6.4.11 As mentioned in paragraph 6.4.9 above it is widely recognised that wind farms save carbon
emissions during operation when compared to fossil fuel energy generation. However, carbon
November 2010 Chapter 6 Page 4
Copyright Partnerships for Renewables Development Co. Ltd 2010 ©