Air travel and transport are said to produce up to 3.5% of global greenhouse gas emissions, amounting to roughly 1.3 billion metric tons of carbon dioxide, methane, and other gasses every year. A key way to reduce this whopping figure would be to electrify aircraft, but this is a feat far easier stated than done. Although electric vertical take-off and landing vehicles (eVTOLs) could eventually sub in for helicopters, larger aircraft (like passenger and cargo jets) require massive amounts of power that today’s all-electric technologies just can’t provide—at least, not yet.
Engineers at MIT’s Gas Turbine Laboratory are developing an electric motor capable of churning out at least one megawatt of power. (Despite the lab’s name, its teams work on far more than just gas-powered turbines.) While current electric motors are limited to a few hundred kilowatts—some eVTOLs draw up to 600 kW—a megawatt electric motor could be sufficient to pair with a gas turbine, thus reducing a jet’s environmental impact. Eventually, the megawatt motor could even pull from a battery or fuel cell to power an aircraft without the help of fossil fuels.
The engineers describe their system in a series of papers published this year. At “about the size of a checked suitcase,” the motor consists of a heat exchanger and a high-speed rotor. The heat exchanger keeps everything cool while transmitting torque. The rotor houses magnets with different polarity orientations and a compact stator, which contains a complex series of copper coils. This whole system is paired with a distributed power electronics system, which (at the same size as the motor) comprises 30 custom circuit boards. These are responsible for changing the stator’s electrical currents at a high frequency, which allows magnetic fields to travel at the high speeds necessary for the motor to work.
Each component has already been tested individually, but the engineers plan to continue testing them to ensure safety before putting them together this fall. From there, the team is bound to face some challenges. The motor has to be capable of pushing out a minimum of 13 kilowatts per kilogram (kW/kg) to be worthwhile, though one paper states the ideal output is 17 kW/kg. As a separate paper out of Norway points out, aerodynamic aircraft design also comes into play. There are also regulatory hurdles inherent to any new air travel technology. If all goes well and the system can be used in practical air travel settings, the team might consider scaling up to a multi-megawatt motor.
