Lessons from the Green Gold Rush

At the 40th anniversary of Earth Day, the so-called green marketplace is littered with failed small businesses that fell victim to fluctuating energy prices, erratic government incentive programs and the country's shifting mood on climate change.

One holdout, as I profile here on CNBC and in WSJ, is a small N.J. heating equipment maker called Energy Kinetics, which stands out for surviving more than 30 years in this space. Among some of its secrets: don't make "green" your only or even main selling chit; don't rely too heavily on transient tax incentives and make sure to always have a "new" product in the pipeline.