Back in 2006, before 'Con-Dem' was just an incorrect spelling of 'condemn', pictures of a fresh-faced David Cameron frolicking in the snow with some huskies graced newspaper front pages. The prime minister-in-waiting was on a trip to Norway to see the effects of climate change - proof of the Conservatives' commitment to the environment.The motto 'vote blue, go green' was integral to the Conservatives' election campaign and three days after being voted into government, Mr Cameron said he wanted to be "the greenest government ever".Today the prime minister had his chance to address representatives from 23 of the world's biggest economies at the  Clean Energy Ministerial. As well as celebrating Britain's role and recommitting to renewables, he focused on the need to make clean energy affordable.

They're deluding themselves. You talk to people from other countries - they think it's a joke. We're making an exhibition of ourselves. Jeremy Leggett, Solar Century

"Our commitment and investment in renewable energy has helped to make renewable energy possible," said the prime minister. "Now we have a different challenge. We need to make it financially sustainable."He announced £350m of new investment in UK renewables, including 800 jobs, and a £300m biomass project by Helius Energy at the Port of Bristol, and said Britain was still the "greenest government ever".A 'damp squib'However Mr Cameron's words were met with a range of disappointment and anger by environmental groups, who believe today's speech reflected a consistent failure on the government's part to give the financial and political backing to its public commitments. "We were led to expect a major policy intervention on the environment, a keynote speech, from the Prime Minister this week, only for his speech to be suddenly downgraded," said David Nussbaum, chief executive at WWF-UK, who added that the speech was a "damp squib"."Today's reassertion by David Cameron that his was still the "greenest government ever" was part of an environmental speech that wasn't", writes Science Editor Tom Clarke. "Last week the Department of Engery and Climate Change sent an email to journalists saying the prime minister would be making a "keynote speech" on renewable energy. It was long anticipated. A few weeks previously energy minster Greg Barker told the Guardian the PM would be making "a major policy intervention" on green energy on April 26th. Green groups were called by speechwriters looking for ideas that could be included in a major speech."Yet today Mr Cameron made some opening remarks to a room full of energy minuisters and little more. The question is: what caused the prime minister to downgrade his appearance? Mindful of other elements of his own party, was he unable to make any grand pronouncements on wind farms because voters are struggling to pay electricity bills during the second dip of a recession? Or due to tensions within the coalition over things like nuclear power he simply doesn't have any new policies to anounce? Either way it's the last time he'll be able to claim he leads the greenest government ever without delivering a meaningful shift in renewable energy generation or greenhouse gases."

Concern over costIt is "incredibly disappointing", Jeremy Leggett founder and chairman of Solarcentury told Channel 4 News. "Mr Cameron was elected in major part because he detoxified the Conservative brand on the promise of being the greenest government ever. He is a fine mile short of that."The concern in the green sector is not just about today's speech, but comes as a result of what many see as an ongoing assault on the renewable sector. Behind the public commitments and gestures, groups of Conservative MPs have openly expressing concerns about the cost of a green agenda in the midst of a recession.Only last week, Tory backbenchers forced an intervention from the prime minister over proposals that would force home owners into making house extensions energy efficient - what they called a "conservatory tax". A group of over 100 Tory MPs also wrote to the prime minister asking that subsidies for offshore wind companies are slashed.Meanwhile George Osborne has talked about the "burden" that environment rules place on British business. In delivering the budget, he justified plans to radically increase the number of gas-fired power plants in the UK and new tax incentives for oil and gas extraction in the North Sea, in favour of offshore wind and nuclear power, by saying "gas is cheap".This government has also announced plans to increase the speed limit (at a high cost to the environment), expand roads and build new airport capacity in the south east.Mr Cameron's acknowledgement today that green energy has led to £4.7bn in investment and created 15,000 jobs over the last year alone, will go some way to alleviate the tension about the cost of going green. But it did not nearly go far enough for green groups, and the renewable energy business sector."All our confidence is shot to pieces," Mr Leggett told Channel 4 News, adding that cutting domestic solar subsidies had hugely undermined the solar industry: "It's the same with investors, and it's part of a bigger pattern. Meanwhile, these are global industries, and other countries are not making the same mistakes."Britain's 'leading role'?Mr Cameron's assertion that Britain is leading the way appears laughable to many within the industry. Just 3 per cent of Britain's energy comes from renewable sources, while the European average is 12 per cent. And a study by the Renewable Energy Association published just this week, shows that the UK is set to miss its target of producing 15 per cent of its energy from renewable sources by 2020 by a long shot.While countries like Germany and Denmark have pledged hundreds of thousands of new jobs in the renewable energy sector at this international global forum, the prime minister today talked about a few hundred."They're deluding themselves," said Mr Leggett, who was at the Clean Energy Ministerial on Wednesday. "You talk to people from other countries - they think it's a joke. We're making an exhibition of ourselves."While detractors complain that accommodating green target is too costly, the renewable energy sector, and the minister of state for energy and climate change, are adamant that investment in the sector will help, not hinder economic growth."Renewable energy not only provides us with clean and secure energy that cuts our reliance on imported fossil fuels, it generates billions of pounds of investment and hundreds and thousands of jobs and is a key growth sector for the UK economy," said Greg Barker recently.But after undermining such high hopes, it will take more than words to convince a struggling sector that the UK is taking the green agenda seriously.