LONDON (Reuters) - Britain, which aims to install about 30 gigawatts (GW) of wind turbines by 2020, will need to build almost as much backup power generation for calm weather periods, an executive from Scottish Power said on Wednesday.
The government is relying heavily on the growth of wind power to meet tough European Union renewable energy targets and promises another 525 million pounds in support for offshore wind as part of Wednesday's budget.
But the more wind turbines Britain erects the more conventional plants it will need.
"Thirty gigawatts of wind maybe requires 25 GW of backup," said Rupert Steele, regulation director at the Scottish arm of Spain's Iberdrola, one of the world's largest wind farm operators.
"The problem is that if you've got a high-pressured area, you may have quite a large area where there's no wind at all ... That happens also offshore," he told Reuters.
Britain plans to install as much as 30 gigawatt of wind capacity, mostly offshore, as part of its efforts to source 20 percent of its energy from renewables by 2020.
At end-2008, it had wind capacity totalling 3.24 GW, including 2.65 GW onshore and 566 megawatts (MW) offshore. It is to reach 4 GW later in 2009 and 5 GW early next year.
Scottish Power had installed capacity of 665 MW by the end of last year and is close to completing Whitelee Windfarm, near Glasgow, which will be Europe's largest onshore site with 140 turbines.
Steele said wind farms usually had a load factor of 30 percent, which meant they provided 30 percent of named plate capacity over the year.
(Reporting by Nao Nakanishi)