CAMBRIDGE, Mass. (AP) -- 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.

Work to create fuel from solar energy has been done for decades, such as by making ethanol from corn or extracting fuel from algae. But Joule says they've eliminated the middleman that's makes producing biofuels on a large scale so costly.

That middleman is the "biomass," such as the untold tons of corn or algae that must be grown, harvested and destroyed to extract a fuel that still must be treated and refined to be used. Joule says its organisms secrete a completed product, already identical to ethanol and the components of diesel fuel, then live on to keep producing it at remarkable rates.

Joule claims, for instance, that its cyanobacterium can produce 15,000 gallons of diesel full per acre annually, over four times more than the most efficient algal process for making fuel. And they say they can do it at $30 a barrel.

A key for Joule is the cyanobacterium it chose, which is found everywhere and is less complex than algae, so it's easier to genetically manipulate, said biologist Dan Robertson, Joule's top scientist.

The organisms are engineered to take in sunlight and carbon dioxide, then produce and secrete ethanol or hydrocarbons -- the basis of various fuels, such as diesel -- as a byproduct of photosynthesis.

The company envisions building facilities near power plants and consuming their waste carbon dioxide, so their cyanobacteria can reduce carbon emissions while they're at it.

The flat, solar-panel style "bioreactors" that house the cyanobacterium are modules, meaning they can build arrays at facilities as large or small as land allows, the company says. The thin, grooved panels are designed for maximum light absorption, and also so Joule can efficiently collect the fuel the bacteria secrete.

Recovering the fuel is where Joule could find significant problems, said Pienkos, the NREL scientist, who is also principal investigator on a Department of Energy-funded project with Algenol, a Joule competitor that makes ethanol and is one of the handful of companies that also bypass biomass.

Pienkos said his calculations, based on information in Joule's recent paper, indicate that though they eliminate biomass problems, their technology leaves relatively small amounts of fuel in relatively large amounts of water, producing a sort of "sheen." They may not be dealing with biomass, but the company is facing complicated "engineering issues" in order to recover large amounts of its fuel efficiently, he said.

"I think they're trading one set of problems for another," Pienkos said.

Success or failure for Joule comes soon enough. The company plans to break ground on a 10-acre demonstration facility this year, and Sims says they could be operating commercially in less than two years.

Robertson talks wistfully about the day he'll hop into the Ferrari he doesn't have, fill it with Joule fuel and gun the engine in an undeniable demonstration of the power and reality of Joule's ideas. Later, after leading a visitor on a tour of the labs, Robertson comes upon a poster of a sports car on an office wall, and it reminds him of the success he's convinced is coming. He motions to the picture.

"I wasn't kidding about the Ferrari," he says.

Amid mounting agreement that future clean, "carbon-neutral", energy will rely on efficient conversion of the sun's light energy into fuels and electric power, attention is focusing on one of the most ancient groups of organism, the cyanobacteria.

Dramatic progress has been made over the last decade understanding the fundamental reaction of photosynthesis that evolved in cyanobacteria 3.7 billion years ago, which for the first time used water molecules as a source of electrons to transport energy derived from sunlight, while converting carbon dioxide into oxygen.

The light harvesting systems gave the bacteria their blue ("cyano") colour, and paved the way for plants to evolve by "kidnapping" bacteria to provide their photosynthetic engines, and for animals by liberating oxygen for them to breathe, by splitting water molecules. For humans now there is the tantalising possibility of tweaking the photosynthetic reactions of cyanobacteria to produce fuels we want such as hydrogen, alcohols or even hydrocarbons, rather than carbohydrates.

Progress at the research level has been rapid, boosting prospects of harnessing photosynthesis not just for energy but also for manufacturing valuable compounds for the chemical and biotechnology industries. Such research is running on two tracks, one aimed at genetically engineering real plants and cyanobacteria to yield the products we want, and the other to mimic their processes in artificial photosynthetic systems built with human-made components. Both approaches hold great promise and will be pursued in parallel, as was discussed at a recent workshop focusing on the photosynthetic reaction centres of cyanobacteria, organised by the European Science Foundation (ESF).

A key point noted by Eva Mari Aro, the vice-chair of the ESF conference, was that there is now universal agreement over the ability of photosynthesis to provide large amounts of clean energy in future. While the sustainable options currently pursued such as wind and tidal power will meet some requirements, they will not be able to replace fossil fuels as sources of solid energy for driving engines, nor are they likely to be capable on their own of generating enough electricity for the whole planet.

Meanwhile the current generation of biofuel producing crops generally convert less than 1% of the solar energy they receive to biomass, which means they would displace too much agricultural land used for food production to be viable on a large scale. There is the potential to develop dedicated systems, whether based on cyanobacteria, plants, or artificial components, capable of much higher efficiencies, reaching 10% efficiency of solar energy conversion. This would enable enough energy and fuel to be produced for a large part of the planet's needs without causing significant loss of space for food production.

As Aro pointed out, photosynthesis evolved by cyanobacteria produced all our fossil fuels in the first place. However the rapid consumption of these fossil fuels since the industrial revolution would if continued return atmospheric carbon dioxide towards the levels at the time cyanobacteria evolved, also heating the planet up to the much higher temperatures that prevailed then.

The objective now is to exploit the same reactions so that the remaining fossil fuels can be left in the ground. Among promising contenders discussed at the ESF conference was the idea of an artificial leaf that would simulate not just photosynthesis itself but also the ability of plants to regenerate themselves. This could be important, since the reactions of photosynthesis are destructive, dismantling the protein complexes where they take place, which therefore need regular reconstruction. Under a microscope, chloroplasts, the sub-cellular units where photosynthesis take place, resemble a permanent construction site, and even artificial systems would probably need some form of regenerative capability.

A future aim therefore is to build an artificial leaf-like system comprised of self-assembling nanodevices that are capable of regenerating themselves – just as in real plants or cyanobacteria. "Fundamental breakthroughs in these directions are expected on a time scale of 10 to 20 years and are recognized by the international science community as major milestones on the road to a renewable fuel," said Aro.

Such breakthroughs depend on further progress in understanding the precise structure and mechanisms of photosynthesis, in particular the protein complex known as photosystem II, which breaks down the hydrogen atoms of water into their constituent protons and electrons to carry the energy derived from sunlight onto photosystem I, leading to production of carbohydrates and ultimately also the proteins and fats required by all organisms.