Some doubt the ability of the UK to meet renewable energy targets
Andrew Bainbridge, the head of Britain's Major Energy Users Council, appears physically pained when he discusses the British government's plans for a vast increase in renewable power generation.
"I remember having lunch on the sea front at Great Yarmouth, and watching a bank of windmills not turning for one hour, and I thought, please, please can we have some nuclear plants, before the lights go out," he told a recent meeting organised by the think tank Open Europe.
"It is not feasible," he added, "to diversify away from fossil fuel dependence to reduce carbon emissions so quickly, in pursuit of arbitrary, politically determined targets of questionable practicality."
The target, which the British government has signed up to, is part of a wider EU plan to increase renewable energy generation to 20% across Europe.
Under the scheme, Britain is expected to produce 15% of its energy from renewable sources within the next 12 years.
The country has a higher renewable mountain to climb than some other EU member states, as its base is so low.
At present, says the Department for Energy and Climate Change (DECC), only 1.8% of Britain's energy is generated from renewable sources.
Much of the burden will have to be borne by wind power. A ten-fold increase in energy from on and offshore farms will be required by 2012.
"Extremely challenging" is how the House of Lord's European committee described the UK target in its report earlier this year.
The report is littered with clarion calls for urgent action on nearly every aspect of renewable energy generation. Lord Freeman, the chairman of the sub committee that drew up the report, fairly crackles with that urgency.
"It's going to mean a national challenge," he says. "If we are serious about greenhouse gases and climate change then renewable energy must be a contribution, and every single citizen has got to rise to that challenge, as well as the government."
The effort from individuals comes from energy efficiency, but perhaps also in accepting higher electricity bills - renewable energy currently costs more.
A tenfold increase in energy from wind power is required by 2012.
Dr Lisa Woolhouse of SKM consulting, whose research the House of Lords used, suggest the premium for renewable energy is somewhere between 10 and 15%.
Renewable energy may be cheaper in the long term, as fossil fuel prices rise again, and a lot cheaper if you take into account the costs of dealing with climate change.
Much of the burden for renewable energy will fall on wind power, because other renewable technologies are not mature enough or cannot be put in place quickly enough.
Open Europe has grave doubts, it believes that as a method of cutting carbon emissions, extensive investment in wind farms simply does not add up.
It would be far cheaper, they say, to pay for the control of deforestation, or build "carbon sinks" through reforestation - or concentrate on energy efficiency to reduce demand.
The renewables target is pretty much a done deal now. But it faces many accusations that it is something for today's politicians to sign up to, and for tomorrow's politicians to fail to meet.
Renewables-sceptics say there are many hurdles to be jumped; the planning problems, the tight supply of turbines and off-shore equipment, access to the national grid.
Environmentalists have a response for each one. Dr Woolhouse says most of the obstacles can be overcome. But will the target be met?
"I don't really think it will. I think we are going to be very lucky to achieve our target, to be honest."