Depending on how exactly it is done anywhere from 5 to 10 times as much.

Or in other words: Synthetic fuels are bullshit. They are incredibly wasteful in terms of energy and thus they are super expensive. They are a greenwashing solution to the problem that cars have become.

The actual solution to climate friendly mobility are less cars. We can't just electrify all cars on the planet. We need viable alternatives to cars like public transport, bicycle infrastructure and cities build for walkability.

This kind of tech will probably only be used in applications where more power is needed than electric could ever deliver.

There is no equivalent to a jet engine for electric planes, so you're forever limited to slow, long flights. To say nothing of military use. Fighter jets being the obvious case, but also tanks and such. There's no way you could ever power an Abrams with electricity.