Silicon Fires Up Renewable Energy Revolution

Large blocks of silicon storing wind and solar power as heat are the latest innovation in the battle to replace all fossil fuels with renewable energy.

Finding a cheap way of storing surplus electricity produced from wind and solar farms is the current preoccupation of the renewable energy industry and governments worldwide.

If it can be done on a large scale, then coal-fired electricity generation − a major cause of climate change − can be phased out entirely, and gas will also soon have a diminishing role.

Battery technology is currently attracting most interest, partly because governments are pressing ahead with introducing electric cars, but also because it is now possible to use large batteries for storing surplus wind and solar power for use at peak times.

But there is increasing interest in storing energy as heat, which can be used for district heating schemes or for creating steam to turn turbines and make electricity when demand is high.

Cheap silicon
Up to now, one of the best ways of storing heat is with molten salts of various kinds.  But cheap and readily-available silicon could now provide a game-changing solution to the problem.

Silicon is the world’s most abundant substance, after oxygen.  It can also be heated up to 2000º C − three times that of molten salts.

Its other advantage, apart from its $2 a kilo price, is that to store the same amount of heat a silicon block would be one-tenth the size of a tank of molten salt.

Among those investing in research is the European Union, which has a €3.3 million research budget for the Amadeus project.  This is led by the Solar Energy Institute at the Technical University of Madrid (UPM), which is hoping to have a small-scale silicon storage prototype up and running by 2019.

The university is so confident the use of silicon will work that it has already set up a commercial company, Silistore, to exploit the technology.

Molten salts is currently the favored method for use with concentrated solar power, using mirrors to heat up a liquid in a tower to generate electricity.

The salts enable surplus heat to be stored in massive tanks at temperatures as high as 600ºC, and then used at night to generate electricity.  Already, 17 commercial systems are being built around the world to make it possible to provide electricity well after the sun has gone down and, in some cases, 24 hours a day.
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But the Europeans will have to hurry.  An Australian company called 1414 Degrees is already developing silicon technology, which it claims can store thermal energy 10 times cheaper than lithium batteries.

The company name comes from the Centigrade melting point of silicon.  It claims its patented system would convert surplus electricity from wind and solar into usable energy at competitive rates.

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