Welsh energy policy has been strongly criticised by leading environmental campaigner George Monbiot.
An artist's impression of a proposed windfarm off Llandudno
Monbiot said he was not singling out Wales, as the UK as a whole was behind in the fight against global warming.
But at the Hay Festival he urged an end to windfarms on land and said a Severn Barrage would cause too much damage.
The Welsh Assembly Government said the challenge was to cut emissions "without compromising energy requirements and economic needs".
Monbiot's book Heat calls on many of us to make big personal sacrifices in the battle against global warming.
He believes that if we do not stop flying, for example, except for essential purposes, we will not be able to reduce our carbon dioxide (CO2) emissions in time to prevent the planet overheating to levels which will threaten civilisation itself.
Monbiot's list of priorities for action are quite different from those of the Welsh Assembly Government's "energy route map".
He dismissed the Severn Barrage, which the UK government also mentioned in last week's Energy White Paper.
"It will cause too much environmental damage," he told me. "There are far better ways of getting energy from the sea - tidal lagoon technology, for example."
He also came out against another central plank of assembly government policy for windfarms on land.
"I think onshore wind has now reached saturation point," he said.
He felt some sympathy with opponents who claimed windfarms on hills were visually intrusive.
"Beyond having a few more windfarms, it'll generate so much antagonism it'll turn people off dealing with climate change."
He also had little time for hydrogen, another energy alternative given favourable mention in the route map.
"There's great hype about hydrogen, but it can't be developed quickly enough to make a difference," he said.
"Governments around the world are investing huge amounts of money in research into it and it could prove useful for energy provision in the home in the future, but in the short to medium term there are far easier and quicker ways to reduce CO2, especially from cars, for example."
So what does Monbiot think should be done in Wales?
His top priority would be a big expansion in offshore wind, followed by more energy from wave and tide.
"Cardigan Bay has great advantages. It's shallow water and it's very windy, meaning you could build on a wide scale producing huge amounts of energy," he said.
"If you build far out to sea, you avoid the problem of visual intrusion. Onshore wind and wave power are admittedly more expensive than other alternatives, but it won't put up our electricity bills by anything like as much as the rises in gas prices we've seen."
The Severn Barrage would run between Wales and England
Monbiot, who moved to Machynlleth in January, said Wales had huge potential to develop and demonstrate new environmental technologies. "It's a massive growth area," he said.
The assembly government has agreed that onshore wind power will make an increasingly important contribution to energy supplies but has said it must also press ahead with encouraging other forms of renewable energy as part of a diverse energy portfolio.
It has said gas will continue to provide an essential part of the mix and that the Severn Barrage held great potential for clean green electricity generation.
First Minister Rhodri Morgan welcomed the UK government's white paper on energy released last week.
Mr Morgan said he applauded "the recognition that the future challenge for the UK and Wales alike lies in delivering cuts in emissions without compromising energy requirements and economic needs."
Mr Morgan said it had confirmed his government's "long-held view that secure, affordable and clean energy can only be obtained through a diversity of supply sources including a strong role for new technologies such as clean coal and a Severn Barrage."