Engineers from South Korea have invented a cement-based composite that can be used in concrete to make structures that generate and store electricity through exposure to external mechanical energy sources like footsteps, wind, rain and waves. By turning structures into power sources, the cement will crack the problem of the built environment consuming 40% of the world’s energy, they believe. Building users need not worry about getting electrocuted. Tests showed that a 1% volume of conductive carbon fibres in a cement mixture was enough to give the cement the desired electrical properties without compromising structural performance, and the current generated...