Three Green Industries Ready for a Growth Spurt Put the kibosh on your turbine dreams. Instead, turn to the past to create an eco-business with a sound future.

It's been more than 30 years since politicians and scientists started talking up their vision of a glorious green economy, one where reformed coal miners and oil refiners tinker on solar panels and windmills, or algae farmers grow biofuel in mile-high agri-towers. High gas prices, oil slicks and clean coal commercials serve as daily reminders that this Popular Science world-of-tomorrow future is as distant now as it was in the bell-bottom era.

Though we're not living under domes in some eco-topia, it doesn't mean the green economy vision failed. In fact, certain elements of the sector are humming along nicely, offering great ground-floor opportunities for entrepreneurs. As long as research, investment and public attention stay focused on emerging green technologies, we are on the verge of an era of economic opportunity similar to the early Internet days.

While putting up wind turbines or harvesting the tides falls under the domain of big corporations like GE and Vestas, there's plenty of work for smaller guys. The biggest business opportunities aren't in redesigning cities and rebuilding the grid, they're in the not-quite-as-sexy arenas of retrofitting, recalibrating and redesigning the wasteful or inefficient technologies we have right now. Here are three green industries ready for a growth spurt.