Alternative energy using plant systems : a comparative study based on adaptation, efficiency and photosystem subunits

Abstract

With continuous rise in world population, the demand for energy is rising at a fast and steady pace. As a result non-renewable oil reserves are fast depleting pushing renewed interest in alternative energy. Plants with its astounding capacity for photosynthesis using which it stores light energy in the form of chemical energy offers a diversified avenue for alternative energy based on biofuels, photosynthetic hydrogen production, photo electrochemical and photovoltaic applications. Though photo electrochemical and photovoltaic applications are promising, they are still not commercially viable owing to low efficiency and stability issues. This project aims to arrive at solutions to the core issues of efficiency and stability by developing a framework where screening of naturally available efficient plant photosystems initially based on the ability of the plant to adapt and later based on the quantum efficiency of chlorophyll fluorescence. Two groups of plants based on shade adaptation were selected. The quantum efficiency of the selected plants was estimated using measurement of chlorophyll fluorescence. The results showed that the sun loving plant Murraya paniculata has photosystem II which operates at significantly higher efficiency compared to the standard spinach. Further analysis of the photosystem protein complexes revealed an unknown protein subunit. Hence the use of photosystems from Murraya paniculata is suggested to be applied for photovoltaic applications in order to improve efficiency. Pigment analysis showed that this plant has higher carotenoid to chlorophyll ratio compared to other indicating that its photosystems are considerably protected from photodamage. Extension of this knowledge is also suggested to improve the stability in photovoltaic applications.