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Hope of cheap solar energy

New Delhi, June 26: An advance in materials chemistry may dramatically reduce the cost of solar energy by replacing an expensive and toxic chemical used to produce solar cells with a chemical found in seawater and used to make tofu.

Scientists at the University of Liverpool in the UK have shown that a chemical called cadmium chloride used in the manufacture of solar photovoltaic cells that turn sunlight into electricity may be replaced with magnesium chloride.

Solar cells based on a material called cadmium telluride (CdTe) are widely accepted as the lowest-cost and an emerging solar photovoltaic cell technology, undercutting silicon which accounts for about 90 per cent of the market for solar cells.

But CdTe solar cells require the use of cadmium chloride, which is expensive — costing about 30 cents per gram — contains toxic cadmium ions and adds to the bill through clean-up costs during production.

The Liverpool scientists have shown through laboratory experiments that cadmium chloride can be replaced with a non-toxic alternative — magnesium chloride. Their work appeared in a paper in the journal Nature on Thursday.

“Magnesium chloride is abundant as it’s recoverable from seawater,” said Major, a physics research fellow at the Stephenson Institute for Renewable Energy at Liverpool.

“This offers a potential cost reduction not only due to the abundant raw material but with the reduction in associated safety costs for handling and waste disposal.”

A comparison of solar cells manufactured using cadmium chloride and magnesium chloride suggests that the performance of the two sets of cells is nearly identical. But the estimated cost of magnesium chloride is less than a cent per gram.

The researchers point out that magnesium chloride is widely used as a bath salt and as a food additive in the production of tofu, a product made from soybeans. The magnesium chloride process could drive costs down and expand the market for CdTe solar cells.

The researchers caution that the solar cells fabricated through the magnesium chloride process would need to be tested for long-term stability. But they do not expect any technological or economic bottlenecks towards scaling up the process for industry applications.

Major said: “If manufacturers were so inclined, the process could be adopted overnight.”

The high cost of solar energy has been a key barrier towards its expansion. India hopes to increase its installed capacity of grid- connected solar energy from a little over 2,200MW in 2014 to about 20,000MW by 2022.