Hi all - thanks for your responses.
CJ - perhaps "environmentally
friendly" was the wrong choice of wording there!!
The point of this really is actually to demonstrate exactly the point you mentioned in a presentation I am currently working on..... that there are more things to weigh up when choosing aviation as a method of transportation or aerial work (even at it's most basic level) than just Co2 emissions (time, cost, ease of use etc...). Not quite jumping on the green bandwagon just yet....
Mr Optimistic/CWatters/Barit1 - great info & links, thanks.