Researchers develop living cement as electricity storage medium

A research team from Aarhus University in Denmark has added living bacteria to cement so that it can store electricity as a kind of supercapacitor. When the power decreases, the material can be reactivated by adding nutrients.

In the study "Living microbial cement supercapacitors with reactivatable energy storage", published in Cell Reports Physical Science, the scientists describe the living cement as an energy storage device. The development is initially a proof-of-concept, i.e. not yet a finished product, but is initially intended to show whether the idea can be fundamentally implemented and works.

Electron transfer through bacteria

The researchers used cement and added bacteria of the type Shewanella oneidensis to it. The exoelectrogenic bacterium is able to survive in environments with and without oxygen. Instead of oxygen, they used metals or special organic transporters. Through metabolic reactions, the bacterium transfers electrons to electron acceptors, resulting in electron transfer.

The bacteria multiplied in the cement and formed a network of charge carriers that can store energy and release it again when required. The researchers found that the biohybrid system has an energy density of 178.7 Wh/kg and a power density of 8.3 kW/kg. Previous cement-based capacitors are significantly below these values. The scientists estimate that a single room made of this cement can store around 10 kWh of energy.

The researchers tested the cement in practice. They connected six cement blocks together and were able to light up an LED-based lamp with the energy stored in them. This was even possible under extreme temperature conditions at a minimum of -15 °C and a maximum of 80 °C. The capacitor capabilities were retained, with the highest performance being achieved at temperatures of around 33 °C.

Regenerative power storage

However, the activity of the bacteria decreases after some time as soon as the nutrients are used up. The scientists therefore integrated a microfluidic system into the cement, which supplies the bacteria with proteins, vitamins, salts, and growth factors. This enabled 80 percent of the original capacity of the cement reservoir to be restored.

The researchers assume that the living cement can be used in buildings to construct walls and in bridges, which can then serve as regenerative electricity storage units. Electricity from renewable energies such as solar and wind power could then be stored locally at low cost without the need for expensive batteries.

(olb)