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Research

Research

Research

Summary

Seventy percent of mankind's current energy needs are met by burning fossil fuels. This is already problematic since oil and gas supplies are limited and because of the adverse environmental effects of rising levels of carbon dioxide in the atmosphere. Moreover this situation is set to get worse as current predictions estimate that our energy needs will double by 2050. Mankind is therefore facing a major challenge to find new sources of clean renewable fuels. Photosynthesis is a biological process able to use solar energy to produce such fuels. The essence of photosynthesis can be described in terms of the following three partial reactions: light harvesting, charge separation, and electron transfer to take electrons from water in order to reduce carbon dioxide to carbohydrate (a fuel). Since solar energy at the earth's surface is rather diffuse, any artificial system designed to convert it into a fuel will need to incorporate a light-harvesting or light-concentration step. The first question any engineer would ask is: what is the design tolerance of such a system? How much architectural flexibility is possible while still retaining both high efficiency light-harvesting and energy delivery to the sink', where that energy can be productively utilized? The project addresses this problem by interrogating natural light-harvesting systems with sophisticated spectroscopic and microscopic techniques, which can tell us how their supra-molecular, meso-scale architecture relates to their overall light-harvesting efficiency. We use as model complexes purple bacteria, which are very simple photosynthetic organisms, for which the structure and function of individual native light-harvesting complexes have been identified. We will first investigate native membranes of purple bacteria by the combined use of time- and space-resolved spectroscopies, in order to correlate their local organization with their light-harvesting function. We will then use this information to begin to construct arrays of artificial light-harvesting complexes, based on synthetic analogues of natural pigments, on surfaces where we can control supra-molecular architecture. Such arrays can, in the long term, be used in devices for producing solar fuels.

Personnel

Funding

Human Frontiers Science Projects

Timeline

September 2009 — August 2012