> really nothing rivals the energy density of petroleum fuels

This isn't actually true, and gets said a lot more than it really should.

This same argument was made for EVs, and here we a short time later, and it turns out that EVs are much more efficient as was predicted by nerds who did the sums before it was practical as a business.

But, you'll say, what about trucks or busses, they need much more fuel and therefore it's still all about energy density?

And I'll say, no, electric busses and trucks are being rolled out right now, because they are cheaper than diesel busses. Because they are more efficient.

Okay, but what about planes, you can't make an electric plane can you, so it's all about the energy density.

Except people are making electric planes, and their pitch is that they're going to be cheaper, because they're more efficient.

We could do shipping etc. but I think you get the point, so we'll skip to:

Wait, you say, really long distance flight that's not possibly with heavy batteries is it, so I'm still right.

Well, no, because you were attaching some magical properties to a fuel that we semi-randomly use today because we found a bunch of it lying around and didn't have anything better.

If kerosene didn't exist, and you had the tech to make it (which we do) why would you make it? Well, it's got the most energy density, right. Except methane and hydrogen score higher on gravametric energy density, so you could make those instead.

But you say, those need cooled and pressurised, not realising that this disproves your own claim that the only thing that matters is energy density. It's the whole system efficiency and cost that matters, just like the familiar EV story.

We mostly use fossil fuels for historical path dependency lock-in reasons. We'll continue to use synthetic versions of them in jets for the same reason, nobody wants to redesign working planes just to save some energy on fuel.

But at some point, new planes, and new air transport systems, will get designed around what is actually the cheapest form of energy we have lying around, and avoiding the externalities of carbon, NOx, and high altitude condensation and they'll probably look quite different than they do today and energy density will be only one of many factors.

A neat anecdote to summarise this, there's a company making 19 seater jets that are electric. They asked a few people in the business, do you fly any planes that size, and they all said no. But one regional airline said, no we don't, but we used to fly planes of that size all the time. We switched because the fuel cost economics for short flights was worse than long flights. We changed what we did, flying further in bigger planes, for cost reasons. They're now attempting to go back to more smaller planes.

https://heartaerospace.com/

> Is there really a market for 19-seater electric aircraft?

> A few decades ago, 19-seater aircraft were very common. Since then, the large acquisition and maintenance cost of turboprop jet engines have made 19-seaters uneconomical. Whereas regional planes averaged at 20 seats in the 1980s, today they average 80 seats.

> Why don’t airlines fly as many 19-seaters anymore?

>When the engine cost-of-ownership can be the same for a 19-seater and a 70-seater, and engine wear is the same whether you fly a 100 km as a 1000 km route, flying short hops with small turboprop aircraft is simply not profitable to airlines.

> How does going electric change the economic equation?

> Our electric motor is about 20 times less expensive than a similarly-size turboprop, and about a 100 times less expensive than the cheapest turbofan. More importantly, maintenance costs are more than 100 times lower. These lower operating costs will make 19-seater electric aircraft competitive to 70-seater turboprop aircraft.