A consortium including Rolls-Royce, Airbus, and Siemens announced last month their success thus far using a hybrid electric engine to power passenger jets. A prototype plane, the E-Fan X, will be complete in 2020, according to a Guardian report.
While this transition is already underway for cars, trains, and even ships, electric power for passenger jets has proven more of a challenge. Batteries able to provide the necessary amount of power weigh two metric tons. Now, a future is finally coming into focus in which passenger jets begin their own transition away from fossil fuel consumption.
Rolls Royce Chief Technology Officer Paul Stein said:
“It is a two-tonne battery pack – the batteries are still fairly heavy. Beating gravity into submission is a huge challenge, so weight is a big issue.”
For the prototype, the project is converting a BAE 146 demo aircraft, which can carry as many as 100 passengers. First, one of the plane’s gas turbine engines will be replaced by a hybrid engine, which will use batteries and an onboard generator that relies on jet fuel. If that effort succeeds, they will attempt to replace a second one of the plane’s engines.
Siemens will design the electric motor itself, Rolls-Royce is in charge of the generator powering the engine, and Airbus will connect the hybrid system to the plane and its flight controls.
By weight, fossil fuels offer roughly 100 times the energy of lithium-ion batteries. In a vehicle like a car or train that rests of the ground, engineers can compensate for the added weight, but flight presents additional challenges.
“Aviation has always eluded electrification largely because of the size and weight of components involved. But technology has moved on apace. Electrification is now poised to make a significant impact,” said Stein.
Stein explained that small air taxis, which carry between 1 and 4 people up to 75 miles, are nearly ready for electrification already. In fact, Airbus flew an electric, two-seat aircraft, called the E Fan, across the English Channel in 2015.
A second category includes small regional jets that seat 10 to 100 passengers, such as the current project. Stein and his colleagues are now working toward a “a fixed wing, regional hybrid design.”
A third category includes the short-haul commercial market, which uses single-aisle planes such as the larger Airbus A320 and the Boeing 737.
According to Bjorn Fehrm, an aeronautical analyst at Leeham News and Comment:
“For the range of today’s thousands of single aisle planes, it will have to be hybrid for at least another 30 years. For long range, it’s unrealistic. There would have to be a breakthrough in fuel cells, or similar.”