> The hard part is getting the CO2 out of the atmosphere in the first place.

From the article: The Martian atmosphere is composed almost entirely of carbon dioxide.

The article is trying to "sell" the technology for two use cases, Mars and climate change mitigation on Earth.

For Mars, the process being inefficient, expensive, slow etc. isn't necessarily a big hurdle as it competes with shipping fuel all the way from Earth, while on Earth, it has to compete with a lot of easily available alternatives.

One could say we've know how to convert CO2 into fuel from the time we first learned agriculture.

Removing CO2 from the atmosphere ("direct air capture") is currently extremely expensive and inefficient, compared to e.g. getting it from some other industrial process or the exhaust from a fossil fueled plant. And you still end up having to ship the fuel which isn't trivial.

Nuclear power is currently more expensive per kWh than renewables. This could potentially change if we were to build many identical plants, which would be viable with this strategy. By building it somewhere far from civilization, lower safety standards could also become acceptable, lowering cost further.

But in order for this to pay off, you'd need an absolutely massive investment, and I suspect nobody wants to take that risk. Building 100 nuclear power plants will be cheaper than building one per plant but still more expensive in absolute numbers, and each plant is already a many-billion project. So for this to work, you'd likely need someone to commit hundreds of billions, and most likely all upfront/at the same time to actually reap the cost benefits for the nuclear plants. And the technology to actually make use of the power isn't there yet.

OTOH, with solar and wind, you can build a plant at basically any scale. A lot of small projects is much easier to make happen than one absolutely gargantuan one.

It'd be much, much, more effective to hook up a nuclear reactor to the grid to take fossil fuel plants offline, and avoid releasing CO2 in the first place.

Though in the long term, it might be useful to do what you propose to produce carbon neutral hydrocarbon fuel for things that need exceptional energy density. Like air travel or space launch vehicles.

> Though in the long term, it might be useful to do what you propose to produce carbon neutral hydrocarbon fuel for things that need exceptional energy density. Like air travel or space launch vehicles.

Yes that's what I had in mind - thanks.

I do remain sceptical that electric cars will save us. If everyone buys an electric car, and then plugs them in the evening to charge - I'm not sure the grid will cope very well. IMHO there is still a valid case for running cars, trucks and trains on hydrocarbons.

Why would they plug them in the evening though? If you're using the car, you're likely to be parking it at a place with a high car density (e.g. a large parking garage or an employer's parking lot), where chargers can be deployed cheaply.

If you have a short commute, you might also not care how fully charged your car is as long as it is enough. So you may specify that you want a state of charge of 50-80% at the end of the day, and the grid can decide when to charge your car. It won't be enough to smooth out all the fluctuations in renewable generation, but it surely will help.

10 million cars (~20% of the cars existing in Germany) attempting to charge is at least 10 GW of load that can be shed when necessary, and significantly more than that in load that you can sink when there is excess power (I'm assuming each car needs to charge e.g. 10 kWh over 10 hours). Wikipedia says the total Regelleistung (operating reserve?) in Germany is 12.5 GW (7 GW in one direction, 5.5 in the other) and that this is responsible for 40% of the cost of the grid fees.

Hourly priced electricity will be the future. Solar is creating this huge abundance of power during the day and electric cars are basically a huge grid of batteries. Since you are not using your car for the majority of the day and usually not during the middle of the day where peak solar kicks in, you can just plug your car in every time you leave it parked and then a charge controller sits and does nothing until power prices drop to the expected lowest price before charging. With some kind of fail safe where they charge anyway if no expected low occurred.

But another problem is that road construction itself is a huge cause of greenhouse gas emissions and isn't solved at all by electric cars. Only fewer and lighter cars would make things better. Personally I think electric scooters could replace a fair bit of car travel. The little sit down ones are sufficient to get you around for most trips and carry a bags worth of stuff.

I am not exactly knowledgeable on the topic, but I believe you might be underestimating the running costs. It's not like you can just leave a nuclear reactor unattended and hope for the best...