Flying cars or taxis, which take the form of electric vertical take-off and landing (eVTOL) aircraft (essentially a mash-up of a helicopter and a plane) have a key hurdle they must overcome: battery technology. In particular, the specific power and energy of lithium-ion batteries needs to increase. Specific power is how much power a battery can deliver at a certain weight. Specific energy is how much energy a battery can hold at a certain weight. A flying taxi’s battery must be able to deliver a lot of power (because flight is energetically demanding) and a fair amount of capacity (so the craft can stay in the air over a reasonable distance and land safely). The heavier the battery, the harder it is for a flying taxi to take off and stay aloft.

So how are batteries doing these days? According to Sripad and Viswanathan’s analysis, current lithium-ion batteries are capable of powering one flying taxi already. Archer Aviation’s Maker aircraft can cruise at 150 mph with a 60-mile range. The duo also identified prototype battery designs developed recently or in-use for select high-performance applications that are suitable for Kitty Hawk’s plane, the Heaviside, which can travel at 180 mph with a 100-mile range. Advanced designs not yet commercially available will open the door to more electric flying taxis with greater speeds and longer ranges.

The bottom line is that better lithium-ion batteries are coming, which will make electric urban aircraft technologically viable on a wide scale. As a bonus, Sripad and Viswanathan also found that small taxis like Archer’s Maker, Kitty Hawk’s Heaviside, or Joby’s 5-Seater are more energy efficient than internal combustion engine cars, and some will even top electric cars, especially over longer distances with more passengers.