Environmental Engineering Reference
In-Depth Information
Chapter 1
Introduction
1.1
Overview
The principal drivers for renewable energy growth have been increasing concerns
over global warming, and the price and security of fossil fuels. A range of policy
instruments has been used to promote low-carbon technologies. Unsurprisingly,
most growth in the early days (1980 onwards) took place in locations with generous
subsidies, such as California, Denmark, Germany and Spain. More recently, there
has been vigorous activity in the United States as a whole, China, India, Portugal
and Ireland. Twenty-eight per cent of Denmark's electricity was generated by wind
in 2012, 16-18% in Ireland, Spain and Portugal, over 10% in Germany and over
6% in the United Kingdom, Romania and Greece (Wiser and Bolinger, 2013).
Wind energy has sustained a 25% compound growth rate for well over
a decade, and total capacity in mid-2013 was 280 GW (Milborrow, 2013).
The annual electricity production capability of this quantity of wind is about
540 TWh - slightly less than the annual consumption in France. With the growth of
the technology has come increased reliability and cheaper generation costs, which
can be set alongside those of the other thermal and renewable sources.
'What happens when the wind stops blowing?' is an intuitive response to
the growth of wind energy for electricity generation, but it is simplistic. In an
integrated electricity system what matters to the system operators is the additional
uncertainty introduced by wind generation. Several studies have now quantified the
cost of variability and uncertainty - which is modest - and also established that the
wind can displace conventional thermal plant. Strictly speaking, wind is variable
rather than intermittent, while thermal plant, that can, and does, 'trip' offline
instantaneously is intermittent.
Large wind turbines for centralised generation now exceed 100 m in diameter
and ratings can be as high as 6 MW. Larger machines are under development.
Off-grid applications are generally much smaller and the criteria for successful
commercial exploitation are different, as generation costs, off grid, are frequently
high, sometimes due to the use of imported fuels.
By mid-2013 nearly 5,000 MW of offshore wind capacity was in operation
and substantial growth is expected in this area, partly on account of the reduced
environmental impact. It is being actively deployed in Denmark, Germany,
the United Kingdom and elsewhere, and is likely to contribute to the continuing
strong growth of wind capacity, which is likely to exceed 300 GW in total by the
end of 2013.
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