Electric planes flying on batteries are no longer a midsummer night’s dream, as an Israeli startup named “Eviation” is planning to introduce the first one by 2021 which will carry nine passengers over distances of up to 650 miles (1045 km). The key technological development that makes this possible is the existence of high-density dry batteries such as the ones that Tesla Inc. has been turning to recently. The American automotive and energy company has recently acquired Maxwell Technologies, along with their ultra-capacitor manufacturing unit. Already, Maxwell’s solutions are on the range of 300 Wh/kg, which is about 30% higher than Tesla’s current solutions, but is that enough for aviation applications?
According to Elon Musk, his bulk estimations about the cross-over point is 400 Wh/kg. He believes that in about five years, we will be there, so long-range passenger plans carrying up to 200 passengers could become a reality much sooner than we previously anticipated. Maxwell has already laid out a path of development that foresees a density increase of 15-25% every 2-3 years, so the short-term goals seems feasible. Moreover, Maxwell’s superior technology and production line expertise will enable Tesla to ramp up production by 16 times for the same space, lower the associated costs, and double the battery life.
As some followers of Elon Musk justifiably commented on Twitter, kerosene’s energy density is about 40 times that of the existing lithium-ion batteries, so in their eyes, the transition doesn’t have much prospect. Elon Musk defended his predictions, telling them that the cross-over point isn’t depending solely on the energy density, but also on the weight of the combustion engines against that of electric motors. Moreover, electric motors are much better at converting energy to motion than their conventional counterparts. When flying, these weight and energy conversion rate differences play a massive role in the overall efficiency, so Musk’s claims are not biased statements aimed at helping Tesla’s shares go up.