Electric vehicles have gone from being a very niche idea that generated hardly any sales each year to being the top-selling cars in the world. This is thanks in large part to the advancement in battery technology, which has made it possible to make EVs that have both long ranges and relatively fast charging times. On top of that, modern EV batteries last a long time, which makes them a practical option for most people.

The obvious success of EVs makes many people wonder whether electric planes could be coming soon. There are some electric planes and helicopters out there, but they are still very impractical for most situations because they are so small and have such a short range.

One of the biggest challenges associated with making electric planes is that the weight of the battery needed is just too high. With cars, the battery is heavy, but it only needs to be powerful enough to make the vehicle go forward and backward. In addition, there are some situations where the weight actually helps (going downhill and recharging the battery via regenerative braking). When it comes to planes, the energy would also have to be used to fight gravity and keep it up in the air.

In order to make electric planes that could be large enough to enter the commercial flight market, and have enough range to at the very least replace the regional jets (which make up 30% of the current pollution from airfare). This is going to be all but impossible with current technologies.

Professor Yet-Ming Chiang of the Massachusetts Institute of Technology thinks there may be another way to make electric planes a reality. His idea is to use liquid metal sodium in a fuel cell and have it react with the oxygen in the air. This would be a major shift from the current use of lithium batteries or even hydrogen fuel cell batteries. Chiang released a statement acknowledging that this is a major change that is a little crazy:

“We expect people to think that this is a totally crazy idea. If they didn’t, I’d be a bit disappointed because if people don’t think something is totally crazy at first, it probably isn’t going to be that revolutionary.”

Crazy or not, it seems that the science behind the idea is at least valid. He and his team wrote a study on the concept and published it in the journal Joule.

So, how powerful would the system need to be in order to be able to be used in the aviation industry effectively? Chiang answers that question:

“The threshold that you really need for realistic electric aviation is about 1,000 watt-hours per kilogram [wh/kg].”

This is a lot higher than the batteries that are in EVs, which are somewhere around 300 wh/kg. In the study, Chaing and his team mention a laboratory version of their liquid metal sodium fuel cells reaching 1200-1540 wh/kg when it is mixed with optimized air. This air needs to have the right level of humidity and be properly purified. While more testing would be needed, the authors of the study believe that in a real-world situation, the power would drop down to around 1000 wh/kg.

What makes this idea even more attractive is what this would do to the pollution caused by the airline industry. The ‘spent’ fuel from this type of plane would be removed from the cell and could either be collected for later industrial use or simply ejected as exhaust. The exhaust would be NaO2, which would actually bond with the carbon dioxide in the atmosphere and remove it, essentially offsetting the carbon emissions from traditional jets.

The result would basically be sodium bicarbonate. It would come out in such small amounts that the people on the ground wouldn’t likely even notice it. Since sodium bicarbonate has a high pH level, it would even help to combat ocean acidification and acid rain, though not on a massive scale.

This study was so promising that a spin-off company, Propel Aero, has been formed to help develop larger scales of this technology to determine if it truly is a practical option for commercial air travel. If it is, it may also have the potential to replace current EV batteries and many other energy storage systems as well.

Of course, there is still a lot of study and experimentation to do before you see an electric jet at your local airport, but the results so far are very promising.

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