I might be wrong here but the whole idea of using low emission vehicles to is change the way we think about our energy usage?
You would get a benefit from planting trees, however thats just a short term carbon sink and isnt a long term solution.
I've never been a fan of the 'carbon sink' theory, its too flawed and is more like a 'get out of jail free card' for carbon emissions, it doesnt change our overall psychology of energy usage one bit.
Saying that, Nuclear power stations generally emit more carbon per kilowatt than gas, oil and coal power stations
.
Its all the associated industry that ramp up the emissions.