Americans know how to personalize just about everything. Want to listen to your favorite song? Just download it onto your MP3 player. Black and gold hightops? Log on to the right Web site and design them yourself. A cheeseburger hold the pickles? Swing by your local fast food joint and it's made to order.

So: Do you want to meet your home's energy needs with five liters of water a day? Just ask Daniel Nocera how to personalize your energy.

In a lecture at the AAAS 2009 Annual meeting in Chicago, Nocera, a professor of energy and chemistry at the Massachusetts Institute of Technology, outlined how one day we might be able to harness the power of the sun and water to run your home and car without releasing greenhouse gases.

What's his solution? A cheap, at-home water-splitting machine. But to understand the concept, you need to understand the context.

Nocera, director of the MIT Solar Revolutions Project, said that there are enough resources on earth to meet the world's energy demands for thousands of years. The problem, he continued, is that these resources--coal, oil, trees--release a tremendous amount of carbon that will harm the climate and doom us before the resources run out.

"We can maintain our standard of living and have just about all the products we want with what we already have," said Nocera. "We just don't know how to deal with all of the carbon dioxide."

In 2008, the world will consume some 12.8 terawatts of energy, with 80% of the energy coming from the burning of carbon-rich oil, coal, and biomass (trees). In 2050, Nocera estimates that the world's 9.4 billion people will consume 28 terawatts.

Nocera called on the developed world to increase the use of renewable resources that don't emit carbon when consumed. The problem, he said, is that most have theoretical production limits. For example, even if all the Class Three winds (5.1 m/s at 10 meters above the ground) were harnessed, we would only get 2 terawatts of energy. If we dammed all of the world's rivers, we would only capture .7 terawatts of hydroelectric energy.

That leaves solar energy, he said, which is currently only .1 % of the world's energy portfolio.

While solar energy is easy to capture, Nocera said that the technology has not penetrated the market because its storage is extremely expensive.

Now, Nocera says, his team has begun developing a highly-manufacturable and inexpensive method of storing solar energy--splitting the water molecule.

The talk was highly technical, but based on his remarks there and elsewhere, here's how it would work:

First, you place solar panels on your roof. Similar to the process of photosynthesis, the sun would split the water molecules into hydrogen and oxygen with the help of a catalyst of cobalt, phosphate, and an electrode.

When electricity is run through the electrode, a thin film of cobalt and phosphate forms, and oxygen is produced. When another catalyst such as platinum is added to the water, hydrogen gas is produced.

Later, the oxygen and hydrogen would be put back together inside of a fuel cell, which would create electricity, without the carbon, to fuel your home.

The splitting of the water molecule releases a tremendous amount of energy, Nocera said, with 5 liters of water containing enough energy to run the average home for a day.

Nocera said that the biggest problem remains how to make this technology cheap enough for personalized use in every house around the world.

"Solar and water can meet the world's future energy needs," Nocera said, adding that if the technology is cheap enough, "individuals from the biggest city to the smallest village will have steady access to energy."

In addition to his work in the laboratory, Nocera, a chemist by training, has helped produce documentaries and TV shows including the pilot that was used to launch the PBS NOVA show, ScienceNow. In addition, he sits on several advisory boards and is working with business and policy leaders to help them develop positions that contribute positively to the energy and sustainability challenges confronting the plant.