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Bricks become batteries

SCIENCE

The humble house brick is now a battery that can store electricity, raising the possibility that buildings could one day become literal powerhouses.


And it’s a simple concept. The tiny pores in house bricks are filled with nanofibres of a conducting plastic that can store charge. It’s enough to power small lights.


Strictly speaking, these power bricks are supercapacitors rather than batteries. Supercapacitors store electricity as a static charge in solids, rather through chemical reactions as batteries do. The advantage is they charge and discharge far faster than batteries, but to date can only hold a small fraction of the energy.


The Guardian reports researchers are working to increase the energy density of supercapacitors as well as the charge speed of batteries. Finding better ways to store electricity would allow abundant but intermittent renewable energy to be stored until needed. “A solar cell on the roof of your house has to store electricity somewhere and typically we use batteries,” says researcher Julio D’Arcy, at Washington University in St Louis. “What we have done is provide a new ‘food-for-thought’ option, but we’re not there yet.”


The energy density of the first power bricks, reports in Nature Communications, is just 1% of that of lithium ion batteries. D’Arcy believes this can be increased tenfold by adding materials such as metal oxides to store more charge in the brick, which would also make the power bricks a commercial proposition.


The idea, though, is to eventually match the energy density of lithium ion batteries. “If so, this technology is way cheaper than lithium ion batteries,” D’Arcy adds.

Supercapacitors can also be charged and recharged many more times than batteries before losing their capacity; power bricks can be cycled 10,000 times.


The cost of lithium ion batteries has plummeted by 90% since 2010, and pumped hydro power schemes are effective where there are mountains. But storing large amounts of electricity remains a challenge. One Swiss company, Energy Vault, uses gravity to store energy by stacking large bricks into a tower, then releasing the energy by dropping the bricks back to the ground. Similar schemes using heavy weights and mineshafts are also being explored.


We’ve fitted solar panels and solar hot water heaters to our roofs. It may not be too long before the bricks themselves can provide even more power.


ABOVE A brick supercapacitor powering an LED light

PHOTO D’Arcy Research Laboratory

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