I commented on the TPA's stance on green taxes last year  and it seems they've still got a bee in their collective bonnet about them, as they've produced a Green Tax Calculator which is designed to allow people to work out the amount they pay annually in green taxes .
The TPA positions itself as a "low tax" campaign group, which is something I'm broadly in favour of, but when it starts focusing on specific taxes, such as green taxes, it isn't criticising the overall level of taxation, it is criticising the tax mix, which is a completely different proposition.
If they are so convinced that green taxes should make up a lower proportion of the overall tax take, I'd expect them to give some solid reason why they are inherently worse that Income Tax, VAT, NI, etc. Unfortunately, that is something they haven't seriously attempted.
What I find really odd is that they've chosen to release figures which paint a picture which is at odds with their message. If you believe their figures (to be fair, I've no reason to believe they are inaccurate), then the average person pays £740 in green taxes per year. In 2007-08, net taxes were £515.9billion , which equates to approximately £8,500 per person, so green taxes make up a single figure percentage of the total, which makes them appear a poor choice of target for a group looking for low taxes generally. Even a worker on a wage well below the average is likely to be paying significantly more in income taxes than in green taxes.
Of the £740 figure, over half (£496) is fuel duty. As a way of raising revenue, I think fuel duty is one of the better methods; it produces some significant positive externalities, such a encouraging the use of more fuel efficient vehicles and going some way towards pricing the scarcity value of road space. If that £496 were to be raised by taxing income instead, the positive externalities would be lost and I can't see any that would replace them. If you earn money, it doesn't create any negative externalities for me, so there is no particular reason I would want the tax system to discourage you from earning money.
The other advantage with fuel duty is that it is much easier to administer. It doesn't require that every company has a knowledge of the system in the way that income tax does, so it creates less of a regulatory burden. There is also much less scope to evade fuel duty than there is to evade income tax, so it needs fewer public sector staff to administer.
Of course, the TPA might argue that they would rather have the £496 removed from the tax burden altogether than transfered to income tax, but that still wouldn't explain why it should be fuel duty that is reduced rather than income tax.