Unlike other portable power sources, which store energy in batteries, the Nectar runs on butane. When a user plugs his phone into the Nectar's USB port, a replaceable butane cartridge releases fuel into the cell. As fuel passes over a ceramic membrane, oxygen ions pass through the surface, which generates a current. The process can run as hot as 1,830°F, so the engineers built a network of insulating silicon-nitride tubes to keep the Nectar's exterior cool. Once the butane cartridge is empty, users can recycle it.