By Jonathan Marshall
Splitting atoms is a proven way to generate energy. Now scientists are working hard on ways to split water molecules to release hydrogen—which someday could be a tremendous way to store clean energy.
Hydrogen is the ideal feedstock for fuel cells, which quietly generate electricity with only water and heat as byproducts. They can also be fed with natural gas or other fuels, but those release CO2, a greenhouse pollutant.
Unlike nuclear energy, splitting water requires more useful energy than it produces. But if the cost and net energy requirement could be reduced enough to drive hydrogen production from sunlight or surplus windpower, the potential benefits of a clean “hydrogen economy” might be immense. Clean vehicles could run on hydrogen instead of gasoline, and large businesses could generate clean power on site with fuel cells.
The key is finding the right chemical shortcut—or catalyst—to split H2O efficiently. Many traditional catalysts are based on platinum—which is called a “precious metal” for a reason. Last I checked, it was selling for about $1,850 an ounce.
But a group of Kentucky scientists just reported in Physical Review B that their computer simulations indicate that a relatively simple alloy of antimony and gallium nitride could be just the trick. When immersed in water, the energy from sunlight alone should break apart the bonds of water molecules and cause hydrogen and oxygen to bubble up.
“Hydrogen production now involves a large amount of CO2 emissions,” said one researcher. “Once this alloy material is widely available, it could conceivably be used to make zero-emissions fuel for powering homes and cars and to heat homes.”
Just three weeks ago, a team of scientists in Quebec reported excellent results with a cheap iron-based catalyst that could rival platinum in efficiency. At about the same time, scientists at the Pacific Northwest National Laboratory reported synthesizing an inexpensive catalyst based on nickel, which splits water about a hundred times faster than the previous record holder. (Unfortunately, it needs a lot of energy, so it’s not yet market-ready.)
Still other scientists are investigating catalysts made of cobalt, manganese, and exotic metal nanoparticles. One company is already commercializing hydrogen technology using titanium dioxide and another, spun off from MIT, is commercializing a solar-powered approach using cobalt and phosphates.
Don’t get too excited. It’s a lot easier to produce journal articles and news releases than cost-effective new industrial processes. And even if hydrogen production becomes cheap, transporting and storing it remain major challenges.