The supercapacitors, composed of cement, carbon black, and water, offer affordable, scalable storage for renewables.
Cement and carbon black, two prevalent materials in human history, might be the foundation for an innovative, affordable energy storage solution. This technology could enhance the viability of renewable energy sources like solar, wind, and tidal by ensuring a consistent energy supply, even with the inherent fluctuations of these sources.
MIT researchers have developed a supercapacitor that has the potential to be integrated into a home’s concrete foundation, where it could store an entire day’s energy without significantly increasing its cost while maintaining its structural integrity.
The team’s new supercapacitors have a high internal surface area due to a cement-based material filled with a dense network of conductive material. Mixing carbon black into cement and water and letting it cure, water reacts with cement creating openings. Carbon fills these spaces, forming wire-like structures in the cement. These fractal-like branches increase the surface area within a compact volume. The carbon structures accumulate charges after soaking in an electrolyte like potassium chloride, which supplies charged particles. The team have discovered that when an insulator separates two such electrodes, they form a potent supercapacitor.
The team have found that a 45 cubic meter block of nanocarbon-black-doped concrete can store around 10 kilowatt-hours, the typical daily energy use for a home. A foundation made of this material could store energy from solar panels or windmills for everyday use.
Supercapacitors also charge and discharge faster than batteries. After determining optimal cement, carbon black, and water ratios, the team created small supercapacitors, around 1 cm across and 1 mm thick, each chargeable to 1 volt. They linked three to power a 3-volt LED. Having validated the concept, their next goal is to craft larger versions, beginning with the size of a car battery and aiming for a 45-cubic-meter model to showcase household power storage capacity. The team has discovered a balance between the material’s storage capacity and structural strength.
Carbon-cement supercapacitors could be used in concrete roadways to store energy from adjacent solar panels, wirelessly charging electric vehicles similarly to rechargeable phones. Early applications might include powering remote homes or buildings using solar panels connected to these supercapacitors.