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Blown away

John McKenna examines the implications of building 10,000 wind turbines to meet renewable energy targets.

The Middle East before it struck oil, Australia before uranium. For the most zealous supporters of renewable power, this is the position that the UK finds itself now: on the verge of a power revolution.

An island nation with vast expanses of coastline to install wind farms and tidal barrages, the UK is one of the richest nations in Europe as far as renewable energy resources are concerned.

Unfortunately, to date we have been pretty poor at tapping into those resources. Across all energy uses – heat, transport, and electricity – only 2% comes from renewable sources, with the declining resource of landfill gas the largest single energy source.

Last week's announcement by the European Union (EU) that 15% of total UK energy demand must come from renewable sources by 2020 represents a massive challenge. It is far from the highest target – Sweden must reach 49% by the same time. But it already produces 39.8% of its energy from renewable sources – so the UK's target is easily the largest jump among EU member states.

Despite electricity only representing 18.7% of total UK energy use, it will be this energy sector that is the focus of efforts to meet the 2020 targets. Of the 15% renewables target, the British Wind Energy Association estimates 8% will come from electricity, 3-4% from heating and just 3% in transport fuel.

Wind power is the fastest growing and most popular renewable energy source in the UK, accounting for the bulk of renewables capacity, which now stands at 4.5% of total UK electricity. To reach the 2020 target, renewable electricity capacity will need to increase tenfold to account for anything between 35% and 50% of total electricity demand.

The majority of this will need to be provided by onshore and offshore wind turbines. Informal estimates by consultant Mott MacDonald show that if 35% of the UK's electricity is to come from renewables, 10,000 turbines with a generating capacity of 36GW will need to be in place.

This assumes UK electricity demand continues to grow at the same rate from 380TWh per year in 2007 to 408TWh per year in 2020.

Currently there is only 2.5GW of wind generating capacity in the UK, so thousands of turbines, will need to be built over the next 12 years.

This equates to roughly £100bn in investment and poses challenges on a number of fronts.

"With onshore [wind] there are challenges in terms of getting the planning permission to build," says Parsons Brinckerhoff planning and environment director Peter Kydd.

"With offshore, it's a question of getting energy from the turbines to the land economically. It will be interesting to see how the national grid responds to that challenge."

It looks likely that the majority of the UK's renewable energy will come from off-shore wind farms. Especially given business secretary John Hutton's promise last December that the Government would free up off-shore sites to allow the development of 33GW of capacity, 8GW of which is already in planning.

Mott MacDonald's scenario anticipates that of the remaining 25GW in capacity up for grabs, 19GW will need to be built by 2020 to meet the targets.

Rather than planning or environment issues, Mott MacDonald energy director Simon Harrison says the main barrier to meeting the targets
will be the struggle to supply enough turbines.

"All the specialist infrastructure needs to scale up with the scale-up," says Harrison.

"A lot of people are saying they are interested in entering the market. I'm not saying that they can't do it but it's going to take time."

Kydd agrees and says that the supply and construction of turbines potentially represents a greater engineering challenge than the construction of the £15bn Severn Barrage, which can meet 5% of UK energy demand (between 17 and 19TWh per year) on its own.

"[With a barrage] once you've got through planning it's rather more straightforward in engineering terms.

"The cost is in construction rather than equipment costs whereas wind, the cost is in provision of turbines themselves."

Hutton last week confirmed the scope of a two year feasibility into the harnessing of tidal power in the Severn estuary. With such pressing

targets now thrust upon the UK, this study is now surely a formality – the barrage must be a shoo-in?

"I don't think there are any guarantees in this world," says Severn Tidal Power Group spokesman and Sir Robert McAlpine engineer Roger Hull.

"However, the targets do help a lot. It makes it clear that you need to go down that route."

ICE energy panel chairman, David Kerr, agrees that the targets will help focus the environmental issues surrounding the barrage in the minds public when the debate over whether it should be built begins.

Ultimately, he concludes, the UK will need a mix of renewables that will include some form of tidal power in order to meet the targets.

"It's a huge, huge challenge," says Kerr. "It will require onshore and offshore wind, tidal power [i.e. the Severn barrage], the use of biomass and a small contribution from emerging technologies."

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