A smart cement mixture that can store electrical energy and discharge it on demand could convert buildings, bridges, curb stones and even street lamps into batteries.
Researchers at Lancaster University have developed a cement mixture, consisting of the waste material flyash and an alkaline solution, which is capable of conducting electricity.
Unlike existing smart concretes, which are typically based on graphene and carbon nanotubes, the new mixture does not contain any expensive materials, and is even cheaper to produce than conventional Portland cement.
In the mixture, known as a potassium-geopolymeric (KGP) composite, electricity is conducted via potassium ions that hop through the crystalline structure, according to project leader Professor Mohamed Saafi, from Lancaster University’s Engineering Department.
“To make cement you have to mix the flyash with an alkaline solution, in this case we use potassium hydroxide and potassium silicate,” he said. “When you mix them together they form a cement material, containing potassium ions that act as the electrolyte.”
The mixture could ultimately store and discharge between 200 to 500W/m2.
A house constructed with exterior or partition walls made with KGP, for example, could store electricity from solar panels during the day, and discharge it at night. Panels built from KGP could also be retrofitted onto homes and other buildings.
A six-metre tall lamppost built from KGP would be capable of storing enough renewable energy to power itself through the evening – typically around 700W.
Meanwhile curb stones could provide power to sensors capable of monitoring traffic, drainage and pollution levels.
Large numbers of KGP-built structures could also be used to balance the grid, storing excess renewable energy and releasing it when demand is high.
“We’re trying to turn buildings and bridges into batteries to reduce the cost of energy,” said Saafi. “At the moment we have a lot of renewable energy sources, but we don’t have a large-scale storage system for all that energy.”
The smart cement mixture can also be used to sense mechanical stress on the structures. Changes in stress, cause by cracks, for example, alter the way potassium ions move through the structure, and therefore the material’s conductivity.
By measuring the material’s conductivity, changes in the structural health of the building could be detected automatically and instantaneously, without the need to install additional sensors.
The researchers are now carrying out further work to optimise the performance of the KGP mixtures, and investigating the use of 3D printing techniques to create different shapes from the smart cement.
The research, which will be published in the journal Composite Structures in October, has been funded by the European Commission’s Horizon 2020 programme, as part of the SAFERUP (Sustainable, Accessible, Safe, Resilient and Smart Urban Pavements) project, led by the University of Bologna.
This seems to be a very good thing, turning buildings into rechargeable batteries and (hopefully) reducing the ranks of solar arrays now rendering our countryside hideous. This development should be encouraged.
I’d just like to ask if it is safe for the building with electrical charge during earthquake? Maybe a greater risk of electrical ark flash.
Units!
Surely the storage capacity should be WHr per m3, not W per m2.
And 700W is not a unit of renewable energy, it is power.
I just love it when reporters totally botch their engineering units of measure!
It could be a shocking experience?
What about phonon batteries using KGP as the matrix with magnesium and copper electrodes?
I understand such cells can recharge themselves thermally (say between 40-50 deg. C, the temperature of hot sand on a sunny day), perhaps we could remove the need for the solar panels at the front end of this scheme. Who knows? I have made a phonon cell about 0.01 square meter, that had strips of magnesium interleaved with copper strips, and matrix over them, and this had an output resistance of approximately 3 Ohms, while in direct sunlight. Sealing of the matrix in my case was not optimal, and would lead to device failure in short order, but the KGP matrix would not require any sort of sealing or transparent cover material at all, could be directly in contact with air (wet air, rain??) without too much degradation.
“storing ‘excess’ renewable energy”
And when do you envisage that happening ?
“At the moment we have a lot of renewable energy sources, but we don’t have a large-scale storage system for all that energy.”
All what energy ? Yes we have a lot of nameplate capacity, but most ‘renewable energy sources’ have low capacity factors
(see – DUKES – https://www.gov.uk/government/collections/digest-of-uk-energy-statistics-dukes#2018 )
Concrete batteries sound a great idea, if a bit off the wall (:-))
what happens when it gets wet ?
what is the effect of reinforcing ?
what voltage ?
Nice idea but where’s the fly ash going to come from when we stop burning coal?
Perhaps volcanic ash could be used.
Any concrete fatigue, radiated electrical fields, chemical change induced by rebar embedded. Clearly a good idea provided these amongst other questions can be answered.
Energy storage is too risky, as the above commentators state. One application might be for insulation purposes. Like most EU programmes this project needs a much tighter objective.