For all their overt attraction, personal carbon credits are almost as intrusive as ID cards and they would fail for many of the same reasons. Lib Dems should be opposing them.
Of course many people would say that we should be backing a scheme which seeks to encourage personal responsibility for our carbon output with the likely consequence of securing an environmentally friendly cut. And indeed such personal responsibility is a good thing.
But the bureaucracy needed to manage a personal credit trading scheme would be immense and the likelihood of massive loopholes equally certain. For these reasons the Government scheme looks doomed to failure.
Any why should my personal habits (at least, those which produce carbon) be known to and logged by the Government. It is all very well having a carbon tax at the petrol pump - because once I've paid, what I do with the fuel is my own business - but I don't want the big brother state noting my every action and billing me at the end of the month as a consequence.
Any carbon allowances scheme is also bound to make victims of some sections of society. Even Brown's 10p tax rate cut was beneficial to most people, but the UK public will stick up for the oppressed and you can bet there would be quite a few with carbon trading.
I am in total agreement with the Lib Dem idoology that taxes are a necessary evil - they should be as low as possible to enable the state to function and provide services and the money should, where possible, be raised from bad things such as pollution rather than good things such as earnings. But any scheme which needs such detailed levels of personal information is probably going to cost billions in administration costs alone.