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MIT engineers develop new energy-storing concrete

Engineers at MIT have developed a potentially revolutionary type of concrete able to store energy. Here’s how this could become an affordable boon for the inevitable renewable revolution.

Imagine a future where the solar panels on our roofs generate energy which is then stored in the walls and foundations of our homes.

It may sound far-fetched, but this is an increasingly realistic prospect thanks to a recent breakthrough at MIT. Civil engineers at the institute have created a new type of concrete able to hold energy through a creative alteration to the material’s usual composition.

By combining concrete with carbon black – a black powder used as ink for the Dead Sea Scrolls around 2,000 years ago – and water, a branching network of long carbon ‘wires’ are formed as the cement hardens. At this point the mix becomes an effective super-capacitor, meaning it can hold an electric charge.

A key advantage over batteries, which work by converting chemical energy into electrical energy, is that super-capacitors do not degrade over time or lose the ability to hold charge.

Researchers say carbon black is also vastly cheaper than rare metal components like cobalt and lithium, and would add little cost to the production of current concrete. There’s also no need to mine, which is an ecological killer.

Cost is often the sticking point at which renewable solutions fall flat, but carbon black could offer an inexpensive way of scaling up green energy at just 3% volume per mixture.

As well as providing power for our homes, it could be used to supplement or boost wind turbines from the base, and even create futuristic roads which can deliver solar power directly to EVs on the fly – say the researchers.

During a study at MIT, the engineers found that energy capacitors attached to concrete could discharge quickly or slowly depending on the device. This discounts uncontrollable variables such as wind and sunlight, and allows for a steady flow of renewable electricity at all times.

The team calculated that a block of doctored concrete measuring 45 cubic metres would have enough capacity to store about 10 kilowatt-hours of energy, which is around the average daily usage of a US household.

‘You can go from 1-millimeter-thick electrodes to 1-meter-thick electrodes, and by doing so basically you can scale the energy storage capacity from lighting an LED for a few seconds, to powering a whole house,’ says Admir Masic, a member of the MIT team.

With proof of principle tests checked off, the team is readying its first prototype sample to be revealed in the next 18 months. Hopefully we begin to pivot away from fossil fuels before then.