Flying Green: The Possibilities And Challenges Of Electric Aircraft

Airplanes release greenhouse emissions into the atmosphere and require enormous amounts of fuel to fly. A Boeing 747 can consume up to five gallons of fuel per mile. But what if planes could be powered by electricity? Though they won’t replace passenger airliners anytime soon, small, zero-emission, electric planes are flying today.

Engineers have been pursing electric flight for decades. In 1979, the Solar Riser became the first manned electric aircraft to fly. It used photovoltaic cells to charge a battery that powered an electric motor, but could only fly five minutes, at which point it could either glide or land.

Many enhancements have been made since, and several models of electric planes are showing signs of promise. Two of the most interesting planes to fly recently are the E430 and the SkySpark.

Yuneec International‘s E430 won the Lindbergh Electric Airplane Prize at the World Electric Aircraft Symposium last month. Yuneec opened a 260,000 square foot factory in China and was the first commercially available electric aircraft, with a price tag of $89,000.

The E430 seats two people and flies up to 95 miles per hour, or 60 miles per hour when cruising. Without passengers the plane weighs 561 pounds, which includes its 184-pound lithium polymer battery that needs three to four hours to charge.

This video from Yuneec shows the plane in action:

The SkySpark set a record for electric airplane air speed when it reached 155 miles per hour last year. It also runs on lithium polymer batteries, though its manufacturer, the Italian startup DigiSky, wants to try hydrogen fuel cells next.

Here is a video of its record-setting flight:

Electric planes capture the imaginations and ambitions of many, including Tesla founder Elon Musk, who has said he’s interested in building an “electric super sonic plane” in the future.

NASA is also behind the cause, helping run Centennial Challenges for Aeronautics competitions to encourage aircraft innovation. Next summer’s competition, the Green Flight Challenge, will center around efficiency: the minimum bar for entry will be for aircraft that can surpass the equivalent fuel-efficiency of 200 miles per gallon per passenger.

The technology is improving, but that doesn’t mean it’s near developed enough to green up 747s. One of the main things prohibiting passenger planes from going electric is battery technology. Batteries with enough juice to power a plane are heavy and large, but airplanes need to be light to take off and stay in the air.

Solar powered airplanes have the advantage of being lightweight in comparison to battery-powered planes. Earlier this summer, a solar powered airplane set a new record by flying for 26 straight hours. Its 12,000 solar cells charged batteries that took over when the sun set. This solar/battery combination can theoretically keep a plane in the air for years, though its size and weight capacity is still limited by battery technology.

Wireless power transmission has also been tested, though far less than battery and solar. The technology sends microwave energy or lasers through the air to an airplane’s receiver. NASA has demonstrated the technology works with small, unmanned solar craft, but has yet to try it on larger aircraft.

Another concept that could help longer flights become more feasible is regenerative soaring, in which a propeller acts as a wind turbine to generate energy when the plane flies through an updraft. The Electraflyer C‘s propeller can be turned into a wind-powered generator at a flip of a switch to charge its lithium-ion-polymer batteries. The plane weighs 380 pounds and can fly about 90 minutes, reaching speeds of up to 80 miles per hour. Once drained, the batteries require a six-hour charge.

It’ll be a long time before your next commercial business flight is green, but those considering a pilot’s license have a few greener birds to choose from.