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Summer Science Exhibition 2006

Power to the people: the molecular revolution in sustainable energy









The Royal Society, London, 6-9 Carlton House Terrace, London, SW1Y 5AG


New apatite-type crystalline material for solid oxide fuel cells.

It has been estimated that the use of fossil fuels is burning through the fossil record at a rate of 20 million years per year. At such rates there can be no question that supplies of gas and oil will run out, and soon. Burning coal for energy would increase greenhouse gas emissions, so what are the alternatives? Matthew Davidson and a team of chemists at the University of Bath may have the answer in the next generation of solar cells, biodiesel, and fuel cells. These technologies have enormous potential', says Matthew. 'The sun provides the earth with more energy in an hour than the global fossil energy consumption in a year, we just need to harness it.'

Efficiencies greater than 35% have been achieved for the conversion of solar to electrical power, but standard solar cells only have efficiencies between 10 and 15%. At those levels it would require 6% of the land area of the USA to harness our annual energy needs,' says Matthew. A promising alternative to these silicon-based solar cells is the dye-sensitised solar cell that mimics photosynthesis the energy generating system of plants. At the University of Bath, Laurie Peter is working on improving the efficiency and stability of these new solar cells. The molecular details of photosynthesis are being established in detail, opening a new avenue to a sustainable hydrogen-based fuel economy,' says Laurie.

Biodiesel transport fuels made from renewable sources such as vegetable oil are already available at filling stations in the UK but a major barrier to their widespread use is the cost of production. Chemical catalysts are needed to speed up the reactions that create biodiesel,' explains Matthew. 'As well as doing this, these catalysts can also react with contaminants in the vegetable oil producing unwanted by-products. Removing either the contaminants or the by-products is necessary but expensive. The team at Bath are developing new catalysts that do not react with contaminants, allowing biodiesels to be made from chip fat and unrefined oils at far lower production costs. But even if such improvements are made biodiesels will only ever represent a short term fix. We can't grow enough rapeseed in this country, or Europe, to supply the demand for oil without compromising food supply,' explains Matthew. 'Importing oil from other countries results in the destruction of rain forest to grow palm oil trees, which makes the overall process very carbon intensive'.

A viable alternative for transport is fuel cells and these have been on trial in zero-emission buses, with the only by-product being water vapour. Fuel cells can also be used for heat and power in homes, but there are still major challenges as the operating costs are high. At the University of Bath, Saiful Islam uses state of the art modelling tools that he likens to computational microscopes' to probe novel materials for fuel cells on the atomic scale. The novel compounds we are studying provide good alternatives to materials currently in use,' suggests Saiful. 'They show improved properties and could lead to the design of better fuel cells in the future'.

Power to the people: the molecular revolution in sustainable energy The Royal Society, London 6-9 Carlton House Terrace London SW1Y 5AG UK