Doing some math. Regional jets get somewhere around 45.9 seat miles per gallon (1). So 30 seats, going 125 miles would take around 80 gallons of jet fuel. This is likely low because all the jets listed are bigger and likely flying longer flights that are more efficient but just go with it.

Jet fuel has a specific energy of 12 kwh/kg and a density of 6.7 lb/gal (2). So 80 gallons of jet fuel is 536 lb, or 243 kg, and contains 2,916 kwh of energy. Jet engines are not very efficient, so lets say only 30% of this energy actually ends up being used. So 875 kwh.

Lets say we are using batteries that are 300 wh/kg (0.3 kwh/kg), which seems on the high side of what electric cars are using now (and that there are no efficiency loses in the electric motors or elsewhere).

Now maybe I messed up my unit conversions but I think that means to carry the same energy onboard you would need 6,428 lbs of batteries. And you are still going to carry atleast 1,600 lbs of fuel on top of that. And you have the weight of both electric and conventional engines.

I could see this reducing costs like they say but when many big costs are fixed (pilot, hangar, etc.) will this actually make sense? Will airlines fly something that has thousands of pounds less payload than a competitor but lower running costs? I don't know but it will be interesting to see.

(1) https://airinsight.com/seat-miles-gallon-fuel-burn-update/ (2) https://en.wikipedia.org/wiki/Jet_fuel