In a groundbreaking new approach to artificial photosynthesis, a cross-disciplinary team at Harvard University has created new technology that uses solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuels. Dubbed “bionic leaf 2.0,” the new system can convert solar energy to biomass with 10% efficiency, far surpassing the 1% efficiency of the photosynthesis seen in the fastest-growing plants.
This advanced solar fuel platform, codeveloped by Harvard University Professor Daniel Nocera and Pamela Silver from Harvard Medical School, builds on the team’s previous artificial leaf they created five years ago, which uses sunlight to split water to produce hydrogen (as the fuel in gas form) and oxygen.
The significant innovation at hand is that the bionic leaf 2.0 uses sunlight to make a liquid fuel, as opposed to hydrogen like previous artificial leaf systems. “The engineered bacteria in the bionic leaf take in the hydrogen from the artificial leaf and combine it with carbon dioxide to make liquid fuels,” says Nocera about the revolutionary new version.
Today’s energy infrastructure can accommodate liquid solar fuel but not hydrogen
For the new bionic leaf to produce a liquid solar fuel as opposed to hydrogen, a gas, is potentially game-changing as that could solve a major problem: “The current energy infrastructure is not set up to use hydrogen as a fuel, though it could via fuel cells. But the implementation of fuel cells is not widespread,” Nocera points out. “The bionic leaf gets around this hurdle by producing a liquid fuel, which the energy infrastructure can accommodate.”
Harvard’s bionic leaf 2.0 could hold the promise of advancing solar energy to where liquid solar fuels can replace fossil fuels.
“The important aspect of this work is that it says one can do artificial photosynthesis, and do so at much higher efficiencies than natural photosynthesis,” Nocera says. “The types of yields we have achieved are notable and at the very least [this research work] sets a path toward realizing a solar fuels (vs fossil fuels) industry, if you will.”
The professor says the upper limit of the bionic leaf’s efficiency is a factor of 10 higher than that of natural photosynthesis for biomass. “The added value of the bionic leaf is that it can make a liquid fuel directly, something that natural photosynthesis cannot accomplish,” Nocera notes. “We have broken a ceiling on natural photosynthesis, showing that we can artificially better nature for solar to fuels conversion.”
What is next for the artificial leaf authority, who is also the Patterson Rockwood Professor of Energy at Harvard University? “I would like to explore applications in the developing world using a new model for technology transfer,” Nocera reveals. “I would like the scale-up and prototyping to be done with scientists, as partners, in the emerging world.”
The research work is detailed in the paper “Water splitting–biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis,” published in the Science journal.
Written by Sandra Henderson, Research Editor, Solar Novus Today.