Storing the sun’s energy for use later is one of the biggest challenges to making solar power more affordable at this point. That’s why energy storage is becoming such a big issue in the solar industry. Now Stanford University scientists are using photovoltaics to turn water into a chemical capable of storing 30 percent of the sun’s energy over long periods of time.
Stanford said it is the most efficient means yet of storing energy produced by the sun in the form of chemical bonds. The team, which published its work in Nature Communications, used triple-junction photovoltaic cells in the system and a unique electrolysis system that used two identical electrolysis devices that could produce twice as much hydrogen from water.
Many researchers are looking into novel ways to split water into oxygen and hydrogen. It creates multiple ways to use the stored energy to produce electricity cleanly. the two can be recombined into water, producing electricity in the process via a fuel cell or the hydrogen can be burned in a combustion engine without producing carbon dioxide.
“Tuning all the elements, electronics and the chemistry was critical,” said James Harris, a professor of electrical engineering at Stanford. “The entire system has to be perfectly balanced or the process wouldn’t work at all.”
The researchers found that 30 percent of the energy produced by the solar cells was collected in the form of hydrogen. Previously the efficiency record for converting water into hydrogen and oxygen via electrolysis was 24.4 percent, Stanford said. Other technologies to electrolyze water into hydrogen, like HyperSolar, are targeting lower levels of efficiency but using less expensive and different types of materials.
“This milestone brings us much closer to a sustainable and practical process to use water-splitting as a storage technology,” said Thomas Jaramillo, an associate professor of chemical engineering and of photon science at Stanford. “Improving efficiency has a remarkable impact on lowering costs. We have to continue work on finding more ways to lower the costs to compete with conventional fuels.”
The team of researchers used extensive equipment in the experiments but realized that the triple-junction solar cells and the platinum catalyzers in the device aren’t practical for industrial purposes. “What we’ve done is demonstrate how a systems approach can vastly improve storage efficiency,” Jaramillo said. “Now we have to find ways to get similar results with less expensive materials and devices.”Tweet