"This is a whole new way of converting temperature differences to electricity that has never existed before," said Paul Werbos, program director for power, control and adaptive networks at the National Science Foundation in Arlington, VA..
If it works, it could be far more efficient than the best solar cells, which convert about 30 percent of sunlight into energy.
Johnson's system could reach 60 percent. But for that to happen, it needs to operate with very high temperatures, upwards of 1,400 degrees Fahrenheit (800 C).
Achieving that temperature will be a challenge, said Werbos.
"They will need new membranes and electrodes, and they will have to prove that they are handling the hydrogen correctly," said Werbos.
So far, the researchers have built a device that works at 392 degrees F. Johnson hopes to have demonstration model working at 1,400 degrees in a year to 18 months.