Whether batteries alone or hybrid engine-generator systems power electric vertical takeoff and landing (eVTOL) aircraft depends on timescale and mission. Electric aviation purists envision battery-powered air taxis and cargo drones crisscrossing cities silently and without combustion exhaust. Hydrocarbon fuels nevertheless store energy far better than batteries, and careful engineering may make more capable hybrid-electric aircraft clean, quiet and cheap to operate. Combustion engines and generators recharging batteries in flight — or driving electric motors directly without batteries — may also save on urban infrastructure.