Bionic Leaves Could Fuel the World
Photosynthesis, that amazing process of nature which extracts energy from the combination of sun, water, and plant materials, may just have been co-opted by scientists to turbo-charge the process and perhaps create another source of clean renewable energies for the planet.
The innovation comes from the collaboration of two teams of scientists at Harvard. One is headed by Dr. Daniel Nocera, Harvard University’s Patterson Rockwood Professor of Energy. Dr. Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at Harvard Medical School, heads the other one.
The concept, disclosed June 3, 2016, in the journal Science, combines solar energy to split water molecules into hydrogen and oxgygen and bacteria to eat the hydrogen and convert it into biofuel. The simple twostep process produces liquid fuels cleanly and with minimal waste. These biofuels can then be used to energize many forms of power generation devices.
While the solution is simple, the innovation process to get to this point was far from that. In Nocera’s description of the what it took to achieve the necessary photosynthesis efficiencies and reported results, a new cobalt-phosphorous alloy catalyst had to be created. That design produced a catalyst which does not include reactive oxygen species as a by-product, which in turn allowed the use of lower voltages in the electrically-driven photosynthesis reaction. Lower voltage means higher efficiencies, and in fact the latest published test results show this system can convert solar energy to relatively clean burnable biomass with 10 percent efficiency. Mother Nature cannot get anywhere near that, with even the fastest growing plants demonstrating only around 1 percent efficiency.
In the long run, the most significant part of these innovations is that the biofuels created, which now include the production of isobutanol and isopentanol as burnable by-products, can do all this with very low incremental carbon emissions. There is still a long way to go to make this a commercial reality, but that it exists at all should give those most concerned about longterm climate change some reason for hope.