On a sunny winter's day in Southern California, a group of students sits in windowless classroom at Los Angeles Trade and Technical College, eyeing the contents of small bottles of alternative fuels.
"This is actually biodiesel, but this is not derived from the soy bean, this one is actually a plant," explains associate professor Jess Guerra to the group.
Guerra teaches a "Diesel Technology" class to those hoping to become part of the green work force, where she instructs the fine points of biofuels. It's a technology that could be just one of the businesses with the potential to drive the U.S. economy right out of the ditch.
Labor experts predict renewable energy and energy efficiency industries could create as many as 37 million jobs -- and students at technical colleges like this one are counting on it.
With President Barack Obama's pledge this week to renew the U.S. economy and jump-start the nation's clean energy future, it's a job outlook that's pretty bright.
Across the country, hundreds of thousands of students, those with jobs and those in search of good work, are now "greening" their skill set in hopes of competing for a host of environmentally friendly jobs, from electricians and metal workers to environmental scientists.
Some of the most promising money-makers are in the fields of wind power development and manufacturing, solar power, fuel cells (low polluters which generate electrical power quietly and efficiently) and, of course, biofuels.
Earlier this week in California, a "Dream Green Job" fair attracted hundreds of San Francisco Bay Area job-seekers to an event at the Commonwealth Club.
"I'm looking for something that really aligns with who I am and what I want to be doing in the world," said Jessica Zdeb, who's searching for a green job.
In addition to representatives from job networking Web sites and green industries like solar power, there were colleges and universities spreading the word about their course offerings, training and degree programs promising to prepare adult students for a greener future.
"I'm pretty excited about prospects here," said Struan Vaz. "I want to understand what's out there, what are people doing? What are the movers and shakers talking about? With that you can make a good decision."
As promising as a green economic boom may be, some in the field still see a few clouds on the horizon.
"Greenjobs.com" CEO Peter Beadle worries the country's current economic woes are having a chilling effect on the sunny prospects of eco-friendly industries looking to expand.
"I believe that the government has to solve the credit crisis before it can tackle the green economy," Beadle said. "I mean it's a fundamental underlining all industry; not just green industry."
And the green industry is feeling the effects of the troubled economy too.
While the number of Beadle's applicants are soaring, the number of available jobs is flattening out. But a "dream green job" can still become a reality for the energized job-seeker.
"It's not an economy where you can be a passive jobseeker," said Caroline McCelland of Green Career Central. "You must be innovative; you must be willing and ready to do the work of doing the research and getting involved and getting engaged."
And career counselors in the green arena say it's important to focus and spend time educating yourself about the big world of renewable and sustainable energy.
"Whether it's solar or wind or hydro, recognize that they are different," Beadle says. "You have to become an expert in one of them."
And that's precisely what thousands of students at Los Angeles Trade and Tech College are doing: becoming experts to bank on a hopefully secure job future that is greener.
"It's very, very rewarding to see them leave here, be successful not only make a difference again in their lives, but they, they impact society as a whole," said Guerra.
ABC News' Lisa Fletcher, Angela Ellis and Carrie McGourty contributed to this report.