Technology

Is a bionic leaf better than a real one?

 By Amanda Saint

Harvard scientists have created a bionic leaf that say goes way beyond what the artificial leaves developed before can do, and that even surpasses the photosynthetic performance of real leaves…

(Cover photo by www.utahpeoplespost.com)

In a recent paper published in Science magazine, the lead researchers, Daniel Nocera, who is the Patterson Rockwood Professor of Energy at Harvard University, and Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at Harvard Medical School, revealed that the system they have developed together, which has been given the nickname of ‘bionic leaf 2.0,’ has actually performed better than a real leaf.

The system uses solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuels. In a recent press statement Nocera said: “This is a true artificial photosynthesis system. Before, people were using artificial photosynthesis for water-splitting, but this is a true A-to-Z system, and we’ve gone well over the efficiency of photosynthesis in nature.”

So how does it work and what does it mean for the future of energy?

The reason why this photosynthesis system has performed so much better it is because of the catalyst. In other versions of this kind of system, including ones that Nocera himself designed, there has been a real issue with efficiency due to the catalyst used to produce hydrogen. Previous catalysts were made from a nickel-molybdenum-zinc alloy, which as well as producing hydrogen, also created reactive oxygen molecules that attacked and destroyed the bacteria’s DNA. To stop this happening, the researchers had to run the system at very high voltages, meaning it was very inefficient.

Bionic leaf turns sunlight into liquid fuel

But bionic leaf 2.0 has overcome this problem. Nocera said: “We have designed a new cobalt-phosphorous alloy catalyst, which we showed does not make reactive oxygen species. That allowed us to lower the voltage, and that led to a dramatic increase in efficiency.”

The new system is able to convert solar energy to biomass with 10 percent efficiency, which is a huge advance on the 1 percent seen in the fastest-growing plants. The scientists are excited about the invention’s potential for the future of energy generation. They say that their bionic leaf means that the days of drilling under the ground and the seabeds to get fuel could soon be a thing of the past.

The potential for this system extends beyond fuel for energy, and Nocera said that it is capable of making any downstream carbon-based molecule so is versatile enough to have application in many different industries. The team has already used it to make PHB — a biodegradable plastic — and the system is already efficient enough to be a commercially viable tool for making fuel and other materials.

The plan is to roll the fuel version out in developing countries and if it fulfills its potential there, then take it to the rest of the world.

about the author
Amanda Saint
Journalist and content writer, specialised in engineering and technology with a focus on environmental sustainability, urbanisation and biotechnology.