It's an interesting conundrum - do you buy a clean tech stock, knowing the company is working hard to solve some of the world's most pressing environmental problems, even when the clean tech industry its self has significant environmental impacts?
I asked a similar question a number of years ago at a socially responsible investing industry conference I was attending - to what extent are social investors looking past the social and environmental impact of the clean tech industry (solar was the topic of the day), simply because the end product has environmental benefits? The response to my question: silence.