Twenty-four hours after leading a rebellion against the government which reduced the coalition's majority to 23, Conservative MP Tim Yeo is still in fighting mode.
"Just as we can't be sure what the gas price will do, so we can't be sure how much the cost of some of these renewable alternatives will come down," he's telling me. We're in his office in Westminster - a huge, airy room high above Parliament Square which rivals many ministerial digs. Yeo is addressing the main governmental argument against his call for a decarbonisation target (that it would knock investor confidence). He makes exactly the same claim the other way, which just goes to show how uncertain much of the debate about energy issues is. "Trying to guess where prices will go in the 2020s is a mug's game, really, and that's why I think the case for a broad, diversified energy mix remains very strong."
There is probably no other policy portfolio which has as many question-marks hanging over it as does the energy and climate change brief. There will always be crime. There will always be ill people in need of treatment. There will always be children to teach. And while the Ministry of Defence must hedge against the different kinds of future unknowable wars that Britain will have to fight, there is no government department which deals quite as much in the imponderable questions of the future as that of energy. There will always be a need to keep the lights on, but in the decades ahead there is no real guarantee that this need will be met.
The question-marks go deeper still, for even the basic rationale for driving through the changes the Department for Energy and Climate Change (Decc) is devoted to still faces scrutiny in some quarters. Just as the consensus over smoking's unhealthy impacts was only achieved at an agonisingly slow pace, so Yeo thinks the same is true of climate change. "I think we are at the end of the intellectual arguments. Almost at the end," he corrects.
"There's a broad consensus now... but there are still people clinging on to the arguments we can still have a fossil-fuel-driven economy globally. I'm probably seen as a robust advocate for the need for action to address climate change. I think some people are keen to seize on any inconsistencies in the position that I and others have set out."
Yeo is talking about the quotes attributed to him by a national newspaper suggesting that "the causes are not absolutely clear". That they were picked up in the run-up to his decarbonisation debate is no coincidence, but it is not one Yeo himself picks up on. "My staff have heard me say these things hundreds of times before!" he says. "I was struck by the level of attention that was paid to this." Yeo, for the record, is sure that the increase in carbon emissions is due to us pesky humans, but accepts "there may be other long-term cycles at work".
The sensitivity with which his remarks are taken bears testament to the prominence of the issues he is dealing with. Energy and climate change is another of those areas where the Conservative party is somehow lagging behind the rest of politics. MPs like Peter Lilley pop up on television suggesting that the costs of investment in renewable energy will continue to exceed the benefits for the next 100 years or so, and aren't happy with the idea at all. In the face of such deep-seated cynicism it's no surprise the Tories slowed the Liberal Democrats down in coalition negotiations.
Yeo is not surprised the chancellor's deal with the Lib Dems did not feature the decarbonisation target he and his energy and climate change committee has called for. "Never been a very green department," he says abruptly of the Treasury. He has more sympathy with the Lib Dems, who voted for the inclusion of a decarbonisation target for 2030 in their autumn conference last year but were then confronted with the coalition's compromise only a couple of months later. Sixteen Lib Dem backbenchers rebelled in Yeo's decarbonisation amendment, which though defeated reduced the coalition's majority to 23. "It is a difficult issue - people will make their own minds up," he says carefully. There is a degree of pessimism about whether the Lords will seek to amend the bill, but Yeo thinks the fight he put up in the Commons was a worthwhile one. "Next year we have the review of the fourth carbon budget," he says (it covers the years 2023 to 2027). "It's absolutely clear that if the government did try to significantly water down the fourth carbon budget there would be a real controversy in parliament."
The select committee Yeo chairs has managed to achieve a strong degree of unity, despite the odd issue where a division is needed here or there, and it's credited with influencing the energy efficiency measures which are in the current energy bill. Yeo's work as chair has been praised, but he is a magnet for criticism too from those who object to the money he makes from the renewable sector. This amounts to well over £100,000 a year.
"I will stand and fall by the judgement of my peers on the committee," he declares. That's all very well. But wouldn't it be simpler and easier for everyone if the chair was able to stand up and make his assessments free from any hint of suspicion? Yeo stares straight at me while I make this point, eyes not flickering one iota as he watches me put the question to him. His answer - one he has given many times before - is calm and assured. "I think it's quite hard for anyone to sustain the argument what I'm doing is the result of financial interests when I was actually doing it 12 years before I had those financial interests," he says.
"My judgements... are better-informed because I talk to people in business more than I otherwise would." Yeo thinks such attention "may increasingly go with the territory", because select committees are becoming more effective and more influential now their chairs are directly elected.
The relationship between businesses, policymakers and policy influencers - and Yeo surely tops the list of the latter - is already a difficult one, where subsidies and investment decisions are as politically sensitive as they are potentially lucrative. Take shale gas, for example, which could prove tricky to extract without upsetting local communities.
"I think people will get more used to all these things and they may also see where the overriding national need is," Yeo says. "They could be persuaded to see that perhaps more clearly if they are offered a more direct share of the benefits."
Yeo's involvement prevents him from being able to see the wood for the trees, but he is clearly comfortable with his own investments. He is very aware, too, that when it comes to energy and climate change things will not get done without a little help here or there. It creates an distinct feeling of unease - but the moral weight of the climate change lobby makes it politically palatable to almost everyone.
"I pointed out the planet has existed for four billion years," Yeo said earlier in our interview, as he outlined his rationale on the science underpinning global warming. "There have been much bigger changes in our climate, but those changes occurred before there were seven billion human beings enjoying a remarkably rich lifestyle." The conclusion is clear: maintaining present levels of affluence requires urgent action on climate change. Not just for Yeo, but for the whole of mankind.