Dan Nocera is a salesman who doesn't need the sale. For his entire career, he's pursued a simple question: Just how do plants take sunlight, combine it with water and get energy out of it?

After 25 years of study, he's begun to mimic the process in a small, cheap gadget. It runs on just a bottle of water a day.

He regularly stumps for the technology at energy conferences, where audiences bubble with curiosity at its many merits. His startup company, Sun Catalytix, is already building prototypes. Last year, it received a $4 million award from the Energy Department's Advanced Projects Research Agency-Energy (ARPA-E) program -- proof that someone thinks it could be a breakthrough technology in waiting.

And if the whole concept fizzles, well, Nocera has a day job: He's a chemistry professor at the Massachusetts Institute of Technology.

"If it doesn't work, I'm done with it. And I really mean this. This is so simple in design and concept, I'm not going to be one of those people who say, 'it's almost there,'" he says. "No. This thing's going to work, or it's not going to work."

Nocera isn't the shy type: He generally says this thing's going to work. As he explains, he takes credit for inventing whole fields of science, with names like "proton-coupled electron transfer." He's as comfortable as he would be before a freshman chemistry class: plain-spoken, a bit foul-mouthed, even brash.

And it's hard to see why he shouldn't be. Scientists have gushed about his invention: One called it "a major discovery with enormous implications for the future prosperity of humankind."

Electricity without the grid

Essentially, Nocera has found a way to do what gadgets on the Internet can do, but far more cheaply.

Today, devices called electrolyzers using clean water can be plugged into a wall socket. They then split the water into hydrogen and oxygen. The hydrogen gets fed to a fuel cell, which generates power.

Ready to buy one? Here's the rub: Nocera says a 1-kilowatt electrolyzer runs a cool $10,000.

That's fine for industrial users who need a quick burst of energy. But the professor has a much different market in mind.

"In the next 40 years, there's 6 billion new energy users coming. They tend to be in countries that don't have a lot of money. And so I can't do the way that you do energy, which is build something big and expensive, and because I know that you have money, I try to recover that money over 30 years," he says. "That's not going to work for poor people -- these 6 billion new people."

What could work, Nocera says, is something he calls "personalized energy." It doesn't require a grid connection -- something most poor people don't have. It doesn't take a degree to operate, just a small volume of water. And it's cheap, cheap, cheap.

Sun Catalytix's device starts off much like the electrolyzer: with a catalyst dipped in water. But instead of getting electricity from a wall socket, the first jolt comes from a small solar panel. When that electricity travels through the catalyst, the water splits into hydrogen and oxygen.

The solar panel can provide the necessary power while the sun's up. Once the sun goes down, Nocera claims, Sun Catalytix's device keeps going.

A device that's been splitting water all day will be releasing hydrogen and oxygen. Corral these gases, and they can flow through a fuel cell, generating power through the dark hours. The emission would be pure water -- a harmless byproduct to the wealthy, a precious one for the poor.

A catalyst that loves dirty water

Nocera's contribution to the device is simple but potentially revolutionary: Make the catalyst cheap and resilient.

"If you took any of the catalysts that are known commercially, put them in water, they immediately begin breaking down, they corrode," he says.

The same goes for Nocera's catalyst, which is made from cobalt, an element he says is easy to find. But as cobalt atoms flake off his catalyst, a small burst of solar power tips them back into a reactive state. Dutifully, the cobalt reattaches to the catalyst and resumes its work.

It's that "healing" property, the professor says, that lets the device run in any kind of water -- fresh or foul.

"Literally, we can just walk out to the Charles River, I can walk out to wastewater, I can walk to water in a gully with human waste, put my catalyst in it and it starts working," he says. "So it's perfectly stable in dirty water streams, which is important to me for the poor."

If there's an Achilles' heel to Nocera's invention, some scientists say, it's that it needs other devices to offer a complete energy package.

"I think it's a very important step," says Andrew Rappe, a chemistry professor at the University of Pennsylvania. "To use a baseball analogy, this is a home run, but we're not at the end of the ballgame."

Mass production -- not home runs -- wins the game

Take the solar panel: Even as costs decline, they're still considered too pricey for widespread use. Want to store hydrogen? You'll need something safe and cheap to keep it -- technology that's not yet established. Also, where does one put the solar panels? To get a decent amount of electricity, one might have to plaster a strip of land with solar cells, hardly a convenience for the world's poor.

Nocera has a comeback: Don't think of energy devices as Boeing jets, but as hamburgers.

A fast-food burger is small, light and cheap. A jet airplane is heavy, expensive and made in small batches.

His 6 billion customers need a hamburger, not a Boeing, he says. Their solar panels won't be top-notch; they'll have lower efficiency, because that saves money and still serves a poor person's comparatively low energy needs. The fuel cell doesn't have to power an American home; a slimmed-down, cheaper unit will do.

Currently, a handmade Sun Catalytix prototype costs about $40. Nocera will devote the ARPA-E funding to making the device simpler to use, easier to maintain. He wants to shore up the connection between the solar panel and the catalyst.

And then, to make it even cheaper, "I do what we always do in our society: I manufacture the piss out of it."

In two years, the professor says, he wants to have the catalyst finished. Meanwhile, he's working to convince solar-panel and fuel-cell companies that 6 billion customers, however poor, represent a juicy market.

If all goes well -- and Nocera expects it will -- he'll have helped engineer an ultra-cheap, zero-carbon solution that could help forestall climate change.

And if it doesn't?

Nocera shrugs. "Then I suck. This is sports, man. I suck."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500