But efficiency does not matter if energy is very cheap or sometimes even free when there is too much sun.

It got around petrol tax rules hence was cheaper than petrol

My impression is that it is usually a very different group of people saying carbon capture is an impractical solution to the people saying wind turbines or solar are a pipedream

My impression has generally been that folks with expertise have felt like carbon capture is an impractical moneysink, vs climate change deniers trying to say the solutions presented could never work

But perhaps I am wrong and there is a meaningful body of experts who thinks carbon capture is an important and viable tool, and/or have been a meaningful body of experts who thought wind power or solar would never have promise. I'm not the most knowledgeable on this subject

The problem with carbon based fuels is that we're unburying them and releasing carbon into the atmosphere which was sequestered under the ground for millions of years, a LOT of it.

If he's taking solar power + CO2 from the air to make his fuel, then when he burns it it's just a closed cycle system, at least no new harm done, just returning the carbon previously captured from the air in the process.

So this has been a dream for literally decades now. I remember back in the early 2000's when carbon nano tubes made the scene and there was a whole buzz about a researcher that created a CNT "liquid" fuel that could be used in a normal ICE engine.

Still waiting on that.

The nazis used this technology during WWII it's that old. Coal to liquid technology fueled their war machine, literally. And the entire process can run on any source of syngas, even syngas made from CO2 reverse water gas shift reaction, and hydrogen from electrolysis. You can use solar power for the entire process, it's just incredibly incredibly energy inefficient once you make a finished fuel product and burn it. Like 19th century steam engine thermal efficiencies for each 1w of green power into the system vs each fraction of a watt of energy burned in an ICE.

Race car engines have teams of engineers who pull engines down after each race, and while the fuel allows you to push performance envelopes its about 30% less energy dense, its also hydroscopic so it absorbs atmospheric moisture and spoils much quicker. Its an alternative, but its very much a trade off in terms of drawbacks.

My impression is that it is usually a very different group of people saying carbon capture is an impractical solution to the people saying wind turbines or solar are a pipedream

Today, yes. In the 90s, not really. Solar and wind have benefited massively from government subsidies to develop out of the prototype stage and into proven effective technologies.

I'm not saying carbon capture is definitely effective, I'm saying there hasn't been enough investment in the field yet to determine if it is or isn't.

Without some means of effective carbon capture, this synthetic fuel project has no environmental benefit.

will only capture carbon which represents a fraction of the externalities of shipping it around.

This sort of outcome definitely concerns me. Logistics costs are so often overlooked until after they become relevant.

The best outcome for a project like this would be some machine that could pull CO~2~ from the air and pump it directly into the fuel synthesizer, but I'm no chemistry expert, that could be impossible or too energy intensive to be worthwhile.

The current tech is huge, clunky and expensive, but at least it's being worked on.