Scientists discover why photovoltaic cells will never beat the green leaves
IF GREEN plants can capture 95 per cent of the total energy from sunlight through the process of photosynthesis, why can't the solar photo-voltaic cells (SPV)? The best SPVS are able to absorb only 25 per cent of the solar energy available on the surface of the Earth -- a fact that has puzzled solar energy advocates for quite sometime.
A team of British researchers have identified the details of the atomic structure of the "light harvesting system" -- the place in the leaf where energy from sunlight is absorbed in a strain of purple bacteria. The findings could help in designing more effective spv cells.
Green plants and photosyntheic bacteria employ an extremely sensitive and effective molecular-antennae system that absorbs individual photons and quickly passes on the energy to the "reaction centre" -- the place where photosynthesis proper, or the splitting of water molecules begin.
The research team from the University of Glasgow and Daresbury Laboratory, Cheshire, used 3-dimensional x-ray crystallography -- a technique used for studying the structure of the "reaction centre". They observed two concentric cylinders, a couple of millionth of a millimetre across, of a spiralling protein molecule, enclosing a ring of chlorophyll (a chemical pigment that initially absorbs sunlight). When a photon excites 1 of the chlorophyll molecules, the energy is transferred quickly around the ring to a point near the reaction centre.
Now that 1 biochemical structure that efficiently captures solar energy is available as a guide, it can become an ingredient in a more efficient future solar cell, they argue.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.