Call it the Jeffersonian energy model. MIT chemistry professor Daniel Nocera’s “personalized energy” plan has every home generating its own electricity and fuel from sunlight, and has power plants, transmission lines and gas stations fading into history.
Nocera has outlined the technology needed to realize this vision. And he says we’re in sight of making the technology economically viable.
The scheme, detailed in an essay in the journal ChemSusChem, boils down to using photovoltaics to generate electricity and solar water splitting to generate hydrogen. The hydrogen would fuel vehicles and power fuel cells for nighttime electricity.
Nocera’s lab developed a key enabling technology last year: a stable, inexpensive water-splitting catalyst made from cobalt and phosphate. Other research teams are working to integrate the catalyst with semiconductor materials in order to power the water-splitting reaction entirely by sunlight.
Nocera assumes that the average American home uses 20 kilowatt hours of electricity a day (the U.S. Energy Information Administration puts the figure at about 30). A 3- by 2.5-meter solar water splitting panel can generate the hydrogen equivalent of 20 kilowatt hours from 5.5 liters of water in three hours, he said.
The challenge to making personalized energy affordable is lowering the cost of the scheme’s four components: water-splitting electrolyzer, photovoltaics, hydrogen storage and fuel cell. The electrolyzer is the most expensive component but the cobalt phosphate catalyst “puts a dent in that,” Nocera said.
In general, three things must happen to make personalized energy affordable, said Nocera.
First, researchers need to make fuel cells more efficient and less expensive. The key is finding alternative cathode materials. Today’s fuel-cell cathodes use platinum, which accounts for 38 percent of a fuel-cell’s cost. Researchers are looking for materials that are abundant, inexpensive and minimally damaging to extract and refine.
Second, researchers need to develop good hydrogen storage systems. Many research teams are working on materials that can store hydrogen at reasonable temperatures and pressures, but this is long-term research. We might see something practical in a decade or two. Another option is storing compressed hydrogen gas in tanks, said Nocera.
Third, researchers need to find ways use sunlight to power water splitting. Many researchers are working on the problem, and many of them are looking at titanium dioxide nanostructures. The cobalt phosphate catalyst developed by Nocera’s group has opened new possibilities here.
University of Washington researchers are working to combine the catalyst with iron oxide, commonly known as rust. The work so far allows sunlight to generate some of electricity needed to drive the water splitting reaction, said Daniel Gamelin, an associate professor of chemistry at the University of Washington.
In the long run, all of the power should come from sunlight, said Gamelin. “As a community, we’re not so incredibly far away from this objective.”
The electricity generating aspect of personalized energy has been around for years in the form of residential photovoltaic systems, said Martin Green, a photovoltaics pioneer at the University of New South Wales. “The challenge is clearly the cheap storage systems,” he said.
Personalized energy is the most direct path to solving the energy challenge and should be a major goal of national and global energy policies, said Nocera.
I like his vision of everyone on the planet owning the means of their own energy production. I’d also like to see an economic and environmental analysis comparing regional, local and personal energy generation and storage.
When do economies of scale make energy produced in large centralized plants less expensive than personalized energy after factoring in transmission/transportation and environmental impact? Is it better economically for a small village to have a shared energy system than personalized energy? How about city centers, where sunlit surface area and storage space are smaller on a per person basis than in neighborhoods, suburbs and rural areas?
Eric Smalley is the editor of Energy Research News. He has written about technology since 1987 and has freelanced for many publications including Discover, Scientific American, Wired News and The Boston Globe on topics ranging from quantum cryptography to global warming.