I don't think any school is necessarily turned off by an environmentalist streak. With all the focus on climate change gov'ts are passing more and more regulation, limiting pollutants. We're starting to see environmental regulation being taken into account into the business model of many major corporations.
With that being said, I do think that some schools (ie Stanford, Ross) might look more favorably at that experience. However, more finance oriented schools such as Wharton and Chicago aren't going to turn you down just because you worked in the environmental industry. I think if you're applying to more finance oriented schools and intend to pursue a career in banking/PE after bschool you'll need to show what how your experience working in the env industry ties into your strengths and goals, just like any other candidate needs to do.