Blocks of cement infused with a form of carbon similar to soot could store enough energy to power whole households. A single 3.5-meter block could hold 10kWh of energy, and power a house for a day, and the technology could be commercialized in a matter of years, the scientists say.

The team worked out that a 45 cubic meter material block of nanocarbon-black-doped concrete would have enough capacity to store about 10kWh of energy

Try to visualise 45 cubic meters for the energy storage for 1 person for 1 day without any heating/cooling