Dow Jones VentureSource and Factiva combined their data sets to compare the number of venture deals across cleantech sectors to media mentions in those same sectors. The time frame is 2007 to 2012.
According to the comparison, energy efficiency doesn't get written about relative to the high level of venture capital interest, while everyone talks about water but no one invests. Though there are a sizable number of cleantech deals done in China, there is, somewhat unsurprisingly, relatively scant press coverage of them.
It's an interesting analysis, blunted perhaps by the assumption that all media mentions are alike and the always imprecise and ambiguous categorization of cleantech deals and sectors.
Here's the graphic. Click to enlarge.