Supercapacitors may eclipse lithium ion batteries in the hybridization of transport and industry. Their energy density is improving. Potential CO2 savings could surpass 1bn tons per year. IRRs of 10-50% can be achieved, even prior to CO2 prices. These are our conclusions after reviewing 2,000 Western patents. GE, Siemens, Skeleton and ZapGo are among the leading companies exposed to the theme.