Why don’t we have electric planes?

When are commercially feasible electric cars going to take to the skies? There are a range of ambitious projects, including regional jets and aircraft that can travel longer distances, to develop electric-powered airplanes. Electrification is beginning to allow for a form of air travel that many wished for, but have not yet seen a flying car.

For decades, the concept of electric-powered flight has been around, but only recently has it started to take off. Today, there are more than a dozen start-ups and businesses exploring battery-electric and hybrid prototypes, and some even say that in the next decade, we might all nibble on pretzels and scroll through in-flight entertainment from zero-emission, battery-powered aircraft.

Nothing similar to the gravity-defying vehicles seen in Blade Runner and Back to the Future are the designs under production today. Instead, slim, futuristic, plane-helicopter hybrids made of lightweight carbon fiber always seem to be. But one that is almost entirely dependent on developments in battery technology is the concept of a personal-sized aircraft that could take off and land vertically, fly safely, and make money.

At least 20 businesses, including legacy aircraft manufacturers including Boeing and Airbus and ride-hailing giant Uber, are creating aerial taxi plans. In order to eliminate the noise and emissions usually associated with helicopters and jetliners, almost all of them promise to create battery-electric aircraft.

How much energy can be contained in a given amount of weight from the on-board energy supply is a key challenge in building electric aircraft. While the best batteries hold approximately 40 times less energy per unit of weight than jet fuel, there is a higher proportion of their energy available to drive motion. Ultimately, jet fuel provides about 14 times more available energy for a given weight than a state-of-the-art lithium-ion battery.

That makes batteries for aviation relatively heavy. Airline companies are already concerned about weight, implementing baggage fees in part to restrict the amount of aircraft to be transported. Road vehicles are able to accommodate heavier batteries, but similar problems remain. The technology that allows Tesla to squeeze 300 miles of range to get 200 miles out of the Bolt from a Model 3 or Chevy is not enough to power more than a two-seater aircraft with a flight range restricted to only a few miles.

The main metric is energy density, the amount of energy contained in a given device, and today’s batteries do not contain sufficient energy to get most planes off the ground. Jet fuel gives us about 43 times more energy than a battery that’s just as big.

To weigh it out, Before it makes economic sense to start the process of converting the U.S. trucking fleet to electric power, batteries would also need to become cheaper. It seems likely that this will happen by the early 2020s.

Flying vehicles are a bit further away because, particularly during takeoff and landing, they have different power needs. Tiny battery-powered drones that carry personal packages over short distances, while traveling below 400 feet, are already in operation, unlike passenger planes. Yet it needs 10 times as much energy or more to transport people and luggage.

In the future, will energy storage technology advance significantly? With battery energy density increasing by 5 to 8 percent per year it is probable. They would need to reach approximately five times their current density for batteries to be at a point where they make sense in small-scale aviation. It is possibly not until 2030 that even hybrid electrical technology can be used in commercial aviation at the current speed of battery and electric engine technology.

In recent years, there has been some important improvement in battery-powered flights. A solar-powered airplane completed its year-long world circumnavigation in June 2016 (the first to do so). There are 17,000 photovoltaic cells protected by Solar Impulse 2 that power their motors and charge their batteries during the day. But no one’s concept of a feasible aircraft is that plane. The cabin was unpressurized, unheated and was able to accommodate only one pilot. Usually, it flew at a ground speed of 30 mph, or about 18 times slower than a gas-powered, normal aircraft.

The Solar Impulse 2 was a positive development, but it’s also a warning of the electric flight’s long path ahead. Another breakthrough was the Long ESA, engineered by renowned aerospace engineer Burt Rutan. It became one of the fastest electric aircraft to fly in 2012, moving a single passenger at 202.6 mph. A Boeing 787, by comparison, travels at 585 mph and can accommodate over 242 passengers. That’s more than twice the velocity of Solar Impulse 2, and 242 times that of humans.

Airplanes powered by zero-emission battery power are the future of flight. The need for electric aircraft will only escalate as carbon emissions continue to rise from air travel and more consumers are worried about their effect on the environment. Before we know it the future will be in the sky.

Check out my related post: Why is it faster to fly east?

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