[anovikov]

But efficiency of 50% is great! What's even the problem about it?

Say, an average price of base load electricity of 43.26EUR/MWh in Germany in 2018 (and that is a very pricey market - country which has a shitload of renewable power) - will result, at 50% efficiency, of energy feed costs of 3.07EUR per gallon of fuel. That's only 1.7x the actual cost of jet fuel in EU as per IATA (https://www.iata.org/publications/economics/fuel-monitor/Pag...).

You should add the capital cost of device itself, but if it's used round the clock, it shouldn't add so much. And if it's not, electricity can be almost free because a lot of the time, renewable power is in excess and can be purchased from the high voltage grid for very cheap (if we are speaking of high throughput industrial units which will probably have hundreds of megawatts connected, and will plug into high voltage grid directly).

All in all, it may get fuel 2x more expensive but it's not such a big deal.