Two ancient and abundant materials could hold the key to storing energy from wind and solar farms, creating homes that are powered from their foundations and roads that charge electric cars as they speed along them.
This is according to a team from the Massachusetts Institute of Technology (MIT) in the US, who found a mix of cement and carbon black could work as a new type of low-cost energy storage system.
The researchers found that – with a bit of water thrown into the mix – the materials can be made into a supercapacitor to store electricity.
The breakthrough is particularly exciting as these carbon-cement supercapacitors are made from readily available materials that can be “locally sourced from virtually anywhere on the planet,” say the researchers.
Because the material is so strong, it could be used as part of the concrete foundation of buildings. A block of the material 3.5 metres wide could store around 10kWh of energy, the average daily electricity usage for a home.
It could also be used to build roads that can provide contactless recharging for electric cars as they drive along, in the same way that phones can now be wirelessly recharged, it was claimed.
Wind and solar farms could also deposit excess energy into the supercapacitors when it is not needed.
The researchers created this new storage system by adding carbon black – a highly conductive material that looks like very fine charcoal – into concrete mixture with cement power and water.
The carbon naturally moves along the branching network the water forms within the mix, resulting in wire-like structures. This gives it an extremely high internal surface area, which is crucial to the charging capacity of the material.
The material is then soaked in potassium chloride, a kind of salt, which provides charged particles. The researchers found that two electrodes made from this material – separated by a membrane – make a powerful supercapacitor.
“The material is fascinating,” said Admir Masic, one of the MIT professors that worked on the project. “You have the most-used manmade material in the world, cement, that is combined with carbon black, that is a well-known historical material — the Dead Sea Scrolls were written with it.”
Another of the professors, Franz-Josef Ulm, compared the cheap and available nature of the materials needed to lithium, which is used in batteries but the supply of which is limited. “That’s where our technology is extremely promising, because cement is ubiquitous.”