Could magnets make all-electric flight a reality?

Airplanes and jets account for about 2% of global carbon dioxide emissions, so electrification of air travel could make a big difference in GHG (greenhouse gas) emissions. But there is a big stumbling block. Take off.

If you look at a chart of energy needed for a plane, it’s not the cruising that eats up all the fuel, it’s the take off. And that makes all electric flight difficult.

The problem is that petroleum-based fuel packs about 20 times the energy density of existing batteries – that is, each kilogram of jet fuel holds about 20 times as much energy as a kilogram of lithium-ion battery.

The other problem is that existing batteries simply can’t discharge the energy required quickly enough to do the job. The battery would literally fry trying to meet the demand.

It is a twisting, torturous route that electrons take to flow through a battery, as they navigate their way through tightly packed carbon, cobalt compounds, and other materials. And that is the hold up in terms of energy discharge.

One solution to get them flowing faster is to make the materials thinner, but that further reduces energy density.

Top researchers think magnets could be the answer

Battery researchers from MIT and CMU

Researchers at MIT are working on a different solution, and are partnering with airline start up Zunum Aero, which ReElectrify has covered before, to look into real life possibilities.

The MIT team, which includes one of the world’s most highly regarded battery pioneers, Yet-Ming Chiang, is experimenting with magnets to straighten the path for the electrons and speed up the discharge rate.

The MIT Technology Review notes that “in a 2016 paper in Nature Energy, Chiang, MIT researcher Jonathan Sander, and colleagues showed that mixing magnetic nanoparticles into the electrode materials, and applying a light magnetic field, helped to create aligned pathways through the electrodes.

Subsequent tests found the discharge capacity of these electrodes, or the rate at which electrons can travel out of the battery, was more than double that of conventional lithium-ion batteries—without sacrificing energy density.

Using those findings as the basis for more work, Chiang is working with mechanical engineering professor Venkat Viswanathan of Carnegie Mellon University on a plan to develop a battery that could power a 12-person plane with 400 miles (644 kilometers) of range. Think New York to Washington, Toronto to Montreal, London to Paris.

Next up – ‘COPPER bird’ on-ground testing

COPPER bird facility for testing airplane electrical systems

Those are the flights where the amount of fuel used at take off is wildly out of proportion with the amount required to keep the plan in the air.

Those short haul flights make up only about 1% of flights, because they are simply not economical. But the goal is to start there, and as batteries improve increase the number of passengers/size of the aircraft and also the range.

Airplanes will always need some fuel to meet safety requirements but advances in batteries make it conceivable that hybrid planes could attain a range of 1,500 miles (2,414 kilometers), by 2035. That range makes up 82% of trips, according to the  US Bureau of Transportation Statistics.

The next steps are to develop and test prototype batteries with the magnetic additives. With promising results, Zunum will put the protoypes into what are known as “copper bird” tests, evaluating the plane’s electricity systems in simulations on the ground.
You can read more about this exciting technology and the background behind it at MIT Technology Review.

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