Wind and solar energy companies are finding it more difficult to attract top executives. As recently as four years ago, renewable energy companies were able to lure managers from Silicon Valley with the promise of tech-industry-like stock options and the chance to lead the fight against global warming.

Now, as Bloomberg News points out, mounting competition from Chinese manufacturers has gutted company profits. Stocks have suffered and potential executives are turning away. First Solar, for example, ousted its chief executive in October and still hasn’t found a replacement, Bloomberg reported. Meanwhile, the chairman and finance chief at Vestas Wind Systems are both leaving as well.

The WilderHill New Energy Index, which comprises 97 renewable energy companies, fell 40 percent last year. According to Bloomberg:

Prices for solar panels fell 51 percent in 2011, and global purchases of wind turbines will fall 14 percent this year from 2010 and won’t surpass 2011 levels for two years, according to Bloomberg New Energy Finance.

There’s also the overhang from the Solyndra bankruptcy, which has left many in the renewable energy industry worrying whether the Obama administration will continue to support subsidies in the face of mounting political pressure during an election year.

The declining stock prices and thinner margins have made the options of renewable energy companies less attractive to prospective executives. The exodus of talent may have already begun, and it may be exacerbated by Congress’ decision Thursday to allow subsidies for the wind industry to expire. That’s expected to lead to widespread layoffs and project cancellations for next year.

All of which seems to support the growing notion that the promise of “clean tech” is being eclipsed by the tangible economic benefits of fossil fuel innovation.