CAMBRIDGE, Mass. – A Massachusetts biotechnology company says it can produce the fuel that runs Jaguars and jet engines using the same ingredients that make grass grow.

Joule Unlimited has invented a genetically-engineered organism that it says simply secretes diesel fuel or ethanol wherever it finds sunlight, water and carbon dioxide.

The Cambridge, Mass.-based company says it can manipulate the organism to produce the renewable fuels on demand at unprecedented rates, and can do it in facilities large and small at costs comparable to the cheapest fossil fuels.

What can it mean? No less than "energy independence," Joule's web site tells the world, even if the world's not quite convinced.

"We make some lofty claims, all of which we believe, all which we've validated, all of which we've shown to investors," said Joule chief executive Bill Sims.

"If we're half right, this revolutionizes the world's largest industry, which is the oil and gas industry," he said. "And if we're right, there's no reason why this technology can't change the world."

The doing, though, isn't quite done, and there's skepticism Joule can live up to its promises.

National Renewable Energy Laboratory scientist Philip Pienkos said Joule's technology is exciting but unproven, and their claims of efficiency are undercut by difficulties they could have just collecting the fuel their organism is producing.

Timothy Donohue, director of the Great Lakes Bioenergy Research Center at the University of Wisconsin-Madison, says Joule must demonstrate its technology on a broad scale.

Perhaps it can work, but "the four letter word that's the biggest stumbling block is whether it `will' work," Donohue said. "There are really good ideas that fail during scale up."

Sims said he knows "there's always skeptics for breakthrough technologies."

"And they can ride home on their horse and use their abacus to calculate their checkbook balance," he said.

Joule was founded in 2007. In the last year, it's roughly doubled its employees to 70, closed a $30 million second round of private funding in April and added John Podesta, former White House chief of staff under President Bill Clinton, to its board of directors.

The company worked in "stealth mode" for a couple years before it recently began revealing more about what it was doing, including with a patent last year for its production of diesel molecules from its cyanobacterium. This month, it released a peer-reviewed paper it says backs its claims.