Energy experts this week challenged Severn Barrage backer Hafren Power’s claim that it has come up with a scheme that is £9bn cheaper than the government’s recently scrapped scheme.
Parsons Brinckerhoff director of strategic consulting Peter Kydd said that on a like-for-like basis Hafren Power’s revived scheme is actually £1bn more expensive than the original proposal.
Hafren said its new scheme, unveiled last month, could be budgeted at £25bn - £9bn less than the original, £34bn government- backed scheme (NCE 17 January).
But its proposal includes just £6bn as a contingency for construction risks.
The original proposal included £18bn construction costs, a further £5.2bn in contingencies, plus a Treasury imposed optimism bias figure of £10.8bn on top of the contingency figure bringing the total cost to £34bn.
As a private sector developer Hafren is not required to include optimism bias.
Stripping away contingencies leaves a base cost of just £18bn for the original government proposal, versus £19bn for Hafren’s scheme.
Kydd said it was very important that the schemes were compared on such a basis.
“It is very important that in a policy context, projects are compared on an apples to apples basis,” Kydd told NCE.
The original scheme was scrapped by the Department for Energy and Climate Change (Decc) in 2010 because of its high cost (NCE 17 January).
Kydd said it was more appropriate to compare the £23.2bn cost of the scrapped Decc scheme withHafren’s claimed £25bn project cost.
Kydd believes Hafren’s proposal should include more contingency for risk because it uses untried technology.
The Hafren barrage would incorporate new low head ebb and flood turbines that are still in development and have yet to reach full scale commercial production.
Kydd’s comments came after the Commons energy and climate change select committee, scrutinised Hafran’s scheme for the second time and heard of the risks of relying on new turbines.
Johnny Gowdy, director of lobby group Regen SW which is seeking alternative plans to a barrage, told MPs that he found it “hard to believe” that a turbine manufacturer could build and test a new turbine to Hafren’s proposed timescale, which involves starting construction in 2015/16.
He said any manufacturer taking on the job would be asked for a performance guarantee and warranty that would take “years to produce”.
“[Hafren] ignores the fact that we are talking about a new concept, one that hasn’t been built yet,” he said.
Hafren Power admitted to MPs that the firm it had lined up to manufacture the turbines had now pulled out of the project but said that it was in discussion with “several more”.
Speaking to NCE, Hafren chief executive Tony Pryor said the problems were being overstated.
“We’ve got 1,000 turbines [to manufacture and install],” he said. “We will sequence the commissioning process.”
Pryor acknowledged that a bi-directional turbine had not been used before, but insisted that it was proven technology.
Kydd and Gowdy both said Hafren has not significantly altered the scheme scrapped by the government in 2010. They said the best way to utilise power in the Severn Estuary would be to build up a series of smaller schemes rather than focus on one megascheme.
“We are not anti-barrage,” said Gowdy. “Our approach is based on looking at the channel as a holistic energy system and adopting a strategy to deploy multiple technologies such as tidal stream, tidal fences, lagoons, wind and wave power,” he said.
He said up to 14GW capacity could be built using this technology.”We need to build something quickly,” he said.
Gowdy said a tidal lagoon in Bridgwater Bay on the north Somerset coast could generate up to 3600MW according to the Severn Estuary Tidal Feasibility. The Stepping Stones Lagoon off the coast of Aberthaw could generate 600MW and built first then used as a trial bed for other technologies.