Do 'green' jobs pay off?

Tom Bogart (dean, academic affairs) was quoted on NorthJersey.com on green jobs:

A growing number of advocates, among them (NJ) Governor Corzine and President Obama, believe that energy efficiency and renewable energy could not only help the environment but replace jobs lost in the recession. 

Critics, however, say that's an expensive and unproven way to create jobs that will destroy jobs in other sectors, and in many cases will be little more than putting a green veneer on existing trades. 

"If you spend a billion dollars, sure you create jobs," said William T. Bogart, an economics professor and dean of York College of Pennsylvania. "The question is, on net, how many?"