ESG investing: it's in every media outlet and on every bank's business plan. A rush to what many call alignment of values with investment goals has led to a flourishing new industry with funds popping up like mushrooms after the rain. Green-tech startups are the new dotcoms, it seems, and the danger of a bubble seems distant—for now.

Interestingly enough, things were very different just a few years ago, as the Wall Street Journal's Scott Patterson noted in a recent article. The past decade, he wrote, saw a pullout of investors from the green energy technology field after a couple of notable demises—one of solar company Solyndra back in 2011 and one of battery maker A123 Systems a year later. READ MORE