TABLE OF CONTENTS The main impetus for renewable energy growth has been increasing concern over global warming, and a range of policy instruments have been used to promote carbon-free technologies; these are briefly reviewed. Unsurprisingly, most growth has taken place in locations with generous subsidies, such as California (in the early days), Denmark, Germany and Spain.
The attributes of the renewable energy technologies are summarised, including those which may develop commercially in the future. However, wind energy has sustained a 25 per cent compound growth rate for well over a decade, and total capacity now exceeds 60,000 MW. With the growth of the technology has come increased reliability and lower generation costs, which are 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. Several studies have now quantified the cost of intermittency which is modest and also established that the wind can displace conventional thermal plant.
While wind turbines for central generation now approach 100-m in diameter and up to 5 MW in rating, with even larger machines under development, off-grid applications are generally much smaller and the criteria for successful commercial exploitation are different, as generation costs are frequently high, due to the use of imported fuels.
In the future, offshore wind is likely...
