This is a very interesting initiative and should yield a lot of good insight into how 'green consumers' behave.
Most importantly for researchers it should also validate the TNS consumer segments (which are based on attitude and claimed behaviour). This will show whether those who talk green and say that they are buying green are actually doing it.
We are swimming in data about 'green consumers' but none of it really addresses the behaviour gap between action and sentiment. And there is a big gap.