LOS ANGELES – From “green carpets” at awards shows to organic fruit served to actors on sets, Hollywood is going all out to promote itself as being environmentally hip.

But is it all just show?

No amount of public service announcements or celebrities driving hybrid cars can mask the fact that movie and TV production is a gritty industrial operation, consuming enormous amounts of power to feed bright lights, run sophisticated cameras, and feed a cast of thousands.

Studios’ back lots host cavernous soundstages that must be air-conditioned to counter the heat produced by decades-old lighting technology. Huge manufacturing facilities consume wood, steel, paint and plastic to build sets that are often torn down and tossed out after filming ends.

The energy guzzling continues on the exhibition side, too, with multiplexes drawing millions of kilowatts to power old-school popcorn makers and clunky film projectors that cash-strapped theater owners are reluctant to replace.

A two-year study released last year by the University of California at Los Angeles concluded that special effects explosions, idling vehicles and diesel generators make the entertainment industry a major Southern California polluter, second only to the oil industry.

Still, financial and public pressures have resulted in many studios expanding their environmental efforts, doing everything from using a biodiesel fuel mixture to run the generators on the set of the Fox show “24” to converting Warner Bros.’ enormous set-building facility to solar energy.

“Public consciousness on this issue has changed dramatically,” said Kyle Tanger, a principal at Clear Carbon Consulting. “The talent themselves are requesting it from some of the studios. And a lot of these things make economic sense.”

Economic benefit can come to studios directly, by switching to more efficient lighting or cooling systems or driving hybrid cars on location, which can save gas. Other projects, such as installing solar power, can take decades to pay off.

But there are other benefits that are harder to quantify. Besides the public relations angle, many performers and other employees want to work with eco-friendly companies, so it also helps in recruiting and retaining employees, Tanger said.

Form and function merged at this year’s Primetime Emmy Awards show.

To symbolize its commitment to energy conservation, Fox had wanted to replace the traditional red carpet with a green one.

The tradition-bound Academy of Television Arts and Sciences, which gives the awards, politely said “no.”

But the carpet that ended up cushioning the heels of such stars as Sally Field and America Ferrera was made from recycled plastic bottles and later cut into pieces and donated to several local schools.

“No doubt some efforts have been window dressing. But I actually think Hollywood is doing far more than people are giving it credit for,” said Terry Tamminen, who served as an adviser to Gov. Arnold Schwarzenegger before starting his own environmental consulting company.

One convenient yet controversial method is the purchase of carbon credits by studios and producers to offset the greenhouse gases from their production activity. The credits attempt to counter such pollution by investing in environmentally friendly projects such as planting trees or funding wind power.

Studios and a growing number of other industries calculate their emissions, then write a check to one of several brokers who funnel the money to projects around the world. The goal is to become carbon neutral by funding activities that reduce an equal amount of emissions.

The 2004 Fox film “The Day After Tomorrow” and last year’s Al Gore documentary “An Inconvenient Truth” offset all or some of their pollution. This year’s “Evan Almighty,” from Universal, donated money to the Conservation Fund to plant 2,000 trees, enough to “zero out” the greenhouse gases produced.

But the practice has come under fire by some who say it is an easy way to avoid the hard work of directly reducing pollution. Others question whether carbon credit payments are actually going to projects that make that much of a difference.

“If you’re going to drive around in a big ol’ Hummer and then buy carbon offsets to mitigate that, that’s like getting drunk on the weekends and throwing some money through the window of an AA meeting and thinking you’re doing something,” said Ed Begley Jr., who was a poster child for energy conservation long before Al Gore made it trendy.

The Federal Trade Commission, meanwhile, has begun examining claims made by the nascent multimillion-dollar carbon credit industry.

Warner Bros., which bought carbon credits for the 2005 film “Syriana,” has also become more aggressive at reducing emissions during all phases of production.

In addition to solar-powered set-building, the studio is recycling sets, using recycled plastic lumber in the construction of some buildings, and printing double-sided scripts where feasible.

Pieces built for the 2001 film “Ocean’s 11” now sit in the Santa Monica offices of the National Resources Defense Council. Sets from this year’s sequel “Ocean’s 13” were donated to decorate the halls of local community colleges.

“You have to start by measuring your own footprint, then reducing it, whether through using alternative fuels, reducing electrical loads or combining trips,” said Shelley Billick, vice president of environmental initiatives at Warner Bros. Entertainment. “It’s too easy to write a check, pay thousands of dollars and say, ‘I’m climate neutral.'”

Last year, Fox parent News Corp. set a goal of being carbon neutral by 2010.

To further that goal, Fox Broadcasting chose its popular “24” series as a case study and to serve as a model for other television productions.

Diesel generators that power the show’s lighting were switched to a mixture that uses 5 percent biodiesel fuel. That percentage will be increased in coming years. The show also has secured energy from solar and wind generation from a local utility for its soundstages.

But News Corp. has a more ambitious goal than simply reducing its own carbon emissions.

“We knew from the beginning that if our goal is to make as many carbon reductions in the world as possible, probably the best way we can do that is through our audiences,” said Rachel Webber, director of energy initiatives for News Corp.

The company concluded that worldwide, it produced the equivalent of 641,150 tons of carbon dioxide. But a rough estimate revealed that the people who read its newspapers, watch its TV shows and browse its Web sites use about 7 billion tons.

“That’s the greatest potential to reduce carbon, but we have to get our own house in order first,” Webber said.

To reach the wider audience, Webber and a climate expert from Harvard University met with show writers and executive producers earlier this year to brainstorm on ways to integrate environmental messages into show plots.

But Webber said Fox is not forcing “tacked on” messages into its shows, but rather offering resources should writers choose to address the issue.

“We can’t use this in a way that doesn’t fit into the show,” Webber said. “It can’t be Jack Bauer driving in a car he otherwise wouldn’t drive in.”

Ultimately, any steps Hollywood takes, big or small, to reduce emissions are positive, Begley said. “There are different shades of green.”