Artificial photosynthesis: A new renewable energy source?

By Haley Zaremba

An international team of scientists has made a major breakthrough for the future of sustainable fuel. They achieved this major milestone by copying the methods of some of the cleanest energy producers on the planet—plants. Scientists from the University of Cambridge and the Ruhr University Bochum have discovered a new technique that mimics the natural process of photosynthesis in plants, which could be used to produce hydrogen fuel, an extremely clean (zero carbon dioxide emissions) and essentially unlimited energy source.

In a paper published in the Nature Energy scientific journal, the team of scientists explained their proof-of-principle method for splitting water molecules into the individual hydrogen and oxygen atoms of which they are composed using sunlight. The technique mirrors photosynthesis, the natural process wherein plants split water molecules when they convert sunlight to energy to feed themselves. This achievement has far-reaching implications—Erwin Reisner, lead author of the study, told Newsweek that “solar energy conversion to produce renewable fuels and chemicals—i.e., solar fuel synthesis—is an important strategy for powering our society in a post-fossil era.”

Artificial photosynthesis is not revolutionary in and of itself—techniques to achieve this effect have existed for decades. What makes this recent discovery so important is its partly artificial, partly natural approach. This is the first time a man-made photosynthesis method has been modeled specifically to produce renewable energy.

Completely artificial photosynthesis is a complex process which requires the use of problematic catalyst materials that are tricky to work with and create significant challenges. Many of these catalysts are either too expensive, toxic, or just inefficient, so while they may work in a lab setting, they are unrealistic for any wide-scale use or commercial applications. By comparison, naturally occurring enzymes are abundant and efficient, making them the perfect solution for sustainable solar fuel synthesis.

The University of Cambridge and the Ruhr University Bochum team is primarily using hydrogenase, an enzyme which has remained dormant in algae for millions of years. Hydrogenase combined with synthetic pigments to provoke sunlight to split water into hydrogen and oxygen unassisted. As Reisner explained, this team is trying to “establish a new line of research by combining the best of the natural and artificial worlds and take highly efficient and abundant biological catalysts, such as enzymes, and combine them with synthetic materials in solar devices for efficient solar fuel synthesis.”

Natural photosynthesis, while extremely effective, leaves room for a lot of improvement. Plants only produce the minimum amount of electricity necessary to survive, taking the path of least resistance. In fact, they only produce about 1 or 2 percent of the energy that they’re potentially capable of converting and storing. With this in mind, the Cambridge-Ruht team looked to higher energy-yield processes that plants have phased out over billions of years of evolution. This is what led scientists to pursue the long-dormant hydrogenase enzyme. Their semi-artificial prototype, the first and certainly not the last of its kind, is already able to utilize much more of the solar spectrum.

This groundbreaking research is just the beginning of a much longer process toward commercialization. The new process is just a prototype that opens the door for a new era of hydrogen fuel and photosynthesis research that will lead to even more massive breakthroughs for clean, sustainable fuel.

This line of research is just one of the many pathways being explored by the many scientists around the globe who are dedicated to finding solutions to the impending end of fossil fuels and a pressing need for cleaner energies. Just a month ago a team of Chinese scientists made a similarly exciting advancement in the production of solar energy by discovering a way to increase the scale of synthesizing liquid solar fuel. At the same time Attis Industries is partnering with Daegu Gyeongbuk Institute of Science and Technology to develop efficient conversion of carbon dioxide and water into hydrocarbon fuels designed to be compatible with current infrastructure, and the University of Amsterdam has found that solar fuels could become competitive with traditional fossil fuels by the 2030s.