We have long known how to my synthetic fuels. Germany with limited access to oil in WWII ran large parts of their war on synthetic fuels. South Africa during their embargo years (because of how bad they treated blacks) wasn't able to get [much] oil and so ran their economy on synthetic fuels. Even today many people use synthetic oil made with the same technology in their cars.

The problem has always been cost. It typically costs 5x more than conventional oil. Still oil is a much denser store of energy than batteries and so for many applications it might be worth using it despite the much higher costs.

The WW2 and SA synthetic fuels were not very green. They were made by processing coal.

Or methane, but that isn't really that important.

Right! Long-distance aviation seems like an obvious application, though companies like Joby might take over the short-distance market with battery-powered airplanes.

Presumably most of the cost of synfuel has been in the energy inputs, right? And solar will drive the cost of intermittent energy down by at least an order of magnitude and possibly two.

As Handmer's post says:

> (...) up until this point no-one has considered scaling these up as a fundamental source of hydrocarbons, because doing so would be cost prohibitive. Why? The machinery is not particularly complex, but the energy demands are astronomical.

The article is all about the cost.

Yes, hydrocarbons have major advantages as a form of seasonal energy storage, and possibly you can burn them in cheaper, less efficient power plants. Round-trip efficiency is inevitably going to be pretty low with electrically generated fuels, but they still ought to be able to outcompete fossil fuels economically once production scales up.

Gas has the advantage that gas turbines are less inefficient than conventional steam, though ultra-supercritical steam (mentioned in the EIA paper) could conceivably take that away, and of course it's easier to ship around over short distances.

Hydrocarbons are great for energy density, but gas turbines are brilliant for power density. That's why we need them (and syn fuels)

What we really need are low-capex thermal power plants with high efficiency so we can turn the gas or kerosene or whatever into electricity in the rare case that we need to, without losing money on having massive amounts of capital investment sitting around idle 95% of the time.

You've got to have the whole fuel production, storage and transportation system ready to go 100% of the time. Raises costs if you do it honestly, if you try to skimp it might not work when you need it.

It might be okay if production and transportation only work some of the time if you can store up enough fuel to ride out the outages. That's how it works today for fuel transportation; gas stations commonly go without deliveries for days or weeks at a time when roads are snowed out, for example, and oil tankers and LNG tankers make their deliveries even less frequently.

In particular, solar and wind won't produce any fuel at night when no wind is blowing, and may not produce enough fuel during the rainy season or winter.

Right now it is solar and wind electricity that is cheap. E-fuel [1] and other forms of chemical storage [2] are a thing but might not be so cheap. Seasonal storage might use methane and avoid the legendary boondoggle that is Fischer–Tropsch [3] but methane is itself a powerful greenhouse gas. A really good methane handling system loses much less but if you lose 1% of it you might as well be burning fossil fuels. Even hydrogen isn't completely benign [4] as it depletes those "negative ions" that were a fad in the 1970s and as a result prolongs the life of other greenhouse gases.

[1] https://en.wikipedia.org/wiki/Electrofuel

[2] https://blog.sintef.com/energy/thermochemical-energy-storage...

[3] https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces...

[4] https://www.nature.com/articles/s43247-023-00857-8

TCES is extremely cheap (megajoules per dollar of rechargeable capacity, compared to tens of kilojoules per dollar for batteries) and will likely be critical to the energy transition, but it won't run your servers overnight or your airplanes over the Atlantic. Things like cycle life are still an issue for TCES. And you need electric power to run your TCES system, so efficiency is still a concern.

I feel like oxidizing methane to methanol shouldn't be rocket science, especially if you have an unlimited amount of energy to use. NADPH does it at scale already. A few more cheap process steps would give you nontoxic ethanol instead.