Comment by danans
2 hours ago
> Powered entirely by batteries, X1 used approximately $5 worth of electricity during its first flight
It's fun to look at the arithmetic behind this to pull out the assumptions. To lift a 25000 lb mass 1100 ft in the air requires just over 10kWh, but that's assuming no air resistance or friction, so let's triple the energy needed to 30 KWh.
Let's add another 10 kWh for forward distance covered (assuming it was mostly gliding). Then let's pad it up to 50kWh for anything else. If they say that was $5 in electricity that implies an electricity price of $0.10/kWh, which is possible with utility scale solar.
I'd guess the actual flight time was only 10 of the 27 minutes, 30 kWh used over 10 minutes is 300kW of peak power.
300kW seems very low compared to equivalent jet powered planes, which output an order of magnitude more power for a 30 seater plane. Even if the electric drivetrain is far more efficient than a jet engine it stretches credulity.
Which of my numbers is off?
The jet planes are flying much higher and are loaded; I'm assuming this one was empty. That would account for the power discrepancy.
Finally, I think you might be still high on the power cost. $.10/kwh is retail cost in the PNW, they might be, um, bullshitting a little and have purchased power at a very good rate at a particular time just so they could say $5. They didn't say every flight would be $5. So energy could have been 3x more than you estimated.
Ooo, sneaky. Not being familiar with flight verbiage, I didn't catch the "27 minute mission" being different than a 27 minute long flight!
I don't believe the $5 cost either.