Chancellor Gordon Brown will this week face the first real test of his eco-credentials since he decided he was going to try and out green rival David Cameron, when he delivers his latest and possibly final budget.
But what would constitute a genuinely environmentally responsible budget and what will green business leaders and environmental activists be looking for when the Chancellor reveals the contents of his red box on Wednesday?
First up let's deal with what should happen but won't.
Gordon Brown, like many politicians, is not intimately acquainted with the words "sorry, I was wrong on that one", so the chances of him rectifying the mess the Treasury has made of the increase Air Passenger Duty just six months after the move was announced are thinner than him closing his dispatch box address with a cheery rendition of "Always Look on the Bright Side of Life".
As the opposition parties have quite rightly pointed out the recent increase in air passenger duty will raise £1bn for the exchequer but have minimal impact on the number of people actually flying and provide no incentive for airlines to invest in greener aircraft.
The airlines have complained that the tax is a "blunt instrument" so Brown should call their bluff and deliver a genuine green tax in the form of a levy on aviation fuel. Of course, the chancellor is never going to adopt a tax mechanism that he ridiculed as a unilateral solution to an international problem when it was proposed last week by the Tories. But duty on aviation fuel remains the simplest mechanism of incentivising airlines to invest in greener engines - which is surely the point of a green tax – and while it may push some flights to the continent as airlines try to avoid the UK's tax it is a price worth paying.
The other green tax environmental activists would love to see is a return of the fuel duty escalator, which Brown binned after a motley crew of truckers and farmers decided to bring the country to its knees back in 2000.
With the motoring lobby also flexing its muscles recently over proposals for road pricing Brown is not going to alienate voters with a mechanism that increases tax on petrol above inflation. However, as environmentalists point out, if the government is serious about its soon to be legally binding target of reducing emissions by 60 percent by 2050 action is required now and higher taxes on fuel would again provide a simple incentive for people to reduce their travel.
Far more likely according to Whitehall sources is an increase in road tax for the most polluting vehicles.
Brown previously introduced a sliding scale for road tax based on cars' fuel efficiency, but with the most polluting band charged just £210 a year environmentalists have repeatedly argued that the levy is not sufficient to stop anyone buying such vehicles.
Friends of the Earth has called for the top rate to be increased almost ten fold to £2,000, and while they're at it they might as well ask for an end to all wars and free beer for everyone on a Thursday given they are talking to a man who hopes to be Prime Minister and has no intention of upsetting Mums on the school run too much.
However, Brown appears to have recognised the £210 charge for the piece of worthless gesture politics that it is and is preparing to almost double it to £400. This is still far less than the sum needed to actually stop people buying such cars - in fact as a proportion of the car's cost £400 a year on a vehicle worth £40,000 plus is actually less than £110 on an £8,000 car. However, the increase should send out an even clearer message that buying a gas guzzler is not in the national interest, and Brown could make the move more popular still if he ring fenced the extra money for green initiatives.
What is less clear is if Brown will endorse the other half of the Friends of the Earth road tax recommendation and remove road tax on more efficient cars. Such a move would upset no one and genuinely change behaviour, but according to Whitehall leaks drivers of the most efficient cars will have to content themselves with a reduction rather than a removal of excise duties.
In a further move designed to offset the stick approach of higher road taxes, Brown is also expected to announce plans to lobby EU finance ministers for a reduction in VAT on energy efficient products to five percent. He has apparently already written to some of his EU counterparts about the move and is said to be keen on incentives where possible, arguing that they will prove more effective than the Tories' plans to limit and tax aviation.
In terms of energy policy, reports today also claim Brown is to exempt from income tax any money households make from selling electricity back to the grid from carbon free sources such as solar panels and wind turbines. It is unclear if this exemption would be extended to businesses.
However, while such an exemption would provide a further financial incentive for people to invest in renewable energy it can hardly claim to be part of a coherent strategy for encouraging micro-generation. The government's fund for helping people with the cost of renewable energy sources is a well-documented "farce", with so little cash available people are having to phone up on the morning of the first day of each month to try and get the over-subscribed subsidy.
Helping people to make more money from solar panels is worthless if they don't have them in the first place because they are waiting to win the low carbon buildings programme subsidy lottery. If Brown is serious about encouraging investment in these technologies an increase to this popular fund is essential.
Furthermore, helping people to make more money selling power back to the grid is pointless if, as suggested by several reports, some of the energy companies are proving rather reluctant to buy the excess energy back. If you are to sell electricity to the grid most households will need a new contract with their supplier and a new electricity meter, both of which have apparently proved difficult to secure.
It is reasonable to assume that most households and businesses currently investing in solar panels and wind turbines are doing so for environmental as much as financial benefits – so perhaps the budget should focus on making it easier for them to afford and install the technology first, before then looking at ways to reward them financially.
For the business community, meanwhile, there is a green wishlist as long as your arm, most of which centres on subsidies and tax breaksthat the Chancellor is either unable or unwilling to deliver. However, there are some simple initiatives that could and should be undertaken.
Firstly the Enhanced Capital Allowances scheme, which promises tax breaks for energy efficient kit such as air conditioning and compact heat exchangers, desperately needs simplifying and publicising. There is no point having such a subsidy if large numbers of businesses are either unaware of it or find the application process too daunting.
Secondly and perhaps most importantly, where are the incentives for home working? The government is desperate to get people off the roads but has never had a clear incentive for those firms that reduce office space and get people working regularly from home. The closest it came was the Home Computing Initiative, which allowed staff to buy IT kit free of VAT, but the scheme was halted because some firms were apparently abusing the system and despite hints from the government that it would launch a replacement initiative nothing has happened.
The trend towards home and flexible working is already well under way, but the government could accelerate it with some well thought out perks, helping to increase productivity and take pressure off the creaking roads and public transport system in the process.
Some of these moves are now bound to appear in the budget while others have nbext to know chance of gaining the Chancellor's approval, but they would all help reduce carbon emissions while perhaps even stimulating economic growth in some areas.
However, with the Chancellor appearing as suspicious of green taxes and subsidies as he is apparently fond of all other revenue generating exercises, we are unlikely to see little more than tinkering round the edges for green businesses.
When it comes to judging Brown's green credentials we are likely to have to wait still further for developments in the oft-touted emissions trading scheme. Brown appears to be unconvinced by the personal carbon credit cards that DEFRA keeps talking about, but he is on record as wanting to expand the EU trading scheme to include far more organisations. A timetable for expansion is unlikely to be set out in the budget - it is an EU-wide scheme after all and Brown would probably love to keep his powder dry on this one until he has the keys to number 10.
But there should be progress soon as the government attempts to hit on a system that will reduce emissions but not alienate voters who according to recent polls are concerned about global warming but reluctant to pay for measures to tackle it.
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