Artificial photosynthesis to provide inexhaustible energy within 20 years?

Scientists are trying to learn lessons from one of nature’s finest miracles, photosynthesis, to harvest energy from the Sun.

Through the photosynthetic process, green plants absorb sunlight in their leaves and convert the photonic energy into chemical energy that is stored as sugars in the plants’ biomass.

Scientists believe that if we can learn from nature and develop an artificial version of photosynthesis we would have an energy source that is absolutely clean and virtually inexhaustible.

“Solar energy is forecasted to provide a significant fraction of the world’s energy needs over the next century, as sunlight is the most abundant source of energy we have at our disposal,” said Graham Fleming, Vice Chancellor for Research at the University of California (UC) Berkeley.

“However, to utilize solar energy harvested from sun­light efficiently we must understand and improve both the effective capture of photons and the transfer of electronic excitation energy,” he said.

Fleming and colleagues describe the principles behind various natural antenna complexes and explains what research needs to be done for the design of effective artificial versions.

In natural photosynthesis, these antenna complexes consist of light-absorbing molecules called “chromophores,” and the captured solar energy is directed to chemical reaction centres ?" a process that is completed within 10?"to-100 picoseconds (a picosecond is one trillionth of second).

“In solar cells made from organic film, this brief timescale constrains the size of the chromophore arrays and how far excitation energy can travel,” Fleming stated.

“Therefore energy-transfer needs and antenna design can make a significant difference to the efficiency of an artificial photosynthetic system.

“There remains a number of outstanding questions about the mechanistic details of energy transfer, especially concerning how the electronic system interacts with the environment and what are the precise consequences of quantum coherence.

“However, if the right research effort is made, perhaps based on synthetic biology, artificial photosynthetic systems should be able to produce energy on a commercial scale within the next 20 years,” Fleming added.

The study entitled “Lessons from nature about solar light harvesting” has been published in Nature Chemistry.