14 DAY TRIAL // According to a paper published in the latest issue of the Royal Society of Chemistry' journal Energy & Environmental Science, researchers at the Rensselaer Polytechnic Institute (RPI) have recently been able to figure out some of the mysteries associated with how plants convert solar energy into chemical energy.
The process, called photosynthesis, is arguably the most important natural process, at least as far as the emergence of complex life is concerned. Without it, there would be no oxygen in the atmosphere, and Earthly lifeforms would still be limited to microorganisms, fungi and lichen.
Plants, bacteria and algae use photosynthesis to convert energy from the Sun into chemical energy they can use. This is done in the presence of carbon dioxide, which the lifeforms take from the atmosphere, and nutrients from the soil, and results in the production of energy and oxygen.
Scientists have been trying to figure out how this conversion process works for quite some time. While the basics are relatively easy to grasp, the intricacies of the phenomenon still elude explanation. The new RPI study represents an important step towards solving the solar energy conversion puzzle.
Experts at the Institute believe that their work may set the foundation for the development of an entirely new class of photovoltaic devices, which would be able to harvest energy from the Sun, and turn it into electricity with far more efficiency than possible with existing technologies.
The investigation was carried out at the RPI Baruch ’60 Center for Biochemical Solar Energy Research, by investigators under the supervision of assistant professor of chemistry and chemical biology K. V. Lakshmi.
The work covers an important portion of the photosynthetic process called the photosystem II. One of the issues associated with this step is that the individual water-splitting reactions that take place as it happens have not been observed directly before.
“The photosynthetic system of plants is nature’s most elaborate nanoscale biological machine. It converts light energy at unrivaled efficiency of more than 95 percent compared to 10 to 15 percent in the current man-made solar technologies,” the team leader explains.
“In order to capture that efficiency in solar energy technology, we must first tackle the basic science of photosynthesis by understanding the chemistry behind its ultra-efficient energy conversion process in nature,” Lakshmi explains.
“Photosystem II is the engine of life. It performs one of the most energetically demanding reactions known to mankind, splitting water, with remarkable ease and efficiency,” she goes on to say.
Previous investigations managed to reveal and study only two of the five steps involved in the photosystem II, or oxygen-evolving, process. The other three could not be deciphered because their state changes rapidly, rendering them unstable.
By using low-temperature illumination of photosystem II, the RPI group was able to capture the third step in the process, and preserve it. They then used an advanced spectroscopic technique called two-dimensional hyperfine sub-level correlation spectroscopy to determine what goes on during this step.
“Water is a very stable molecule and it takes four photons of light to split water. This is a challenge for chemists and physicists around the world as the four-photon reaction has very stringent requirements,” Lakshmi concludes.