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Comment by rwke | Hacker News Reader

I’m not very deep into the topic, but this new process might positively affect the economics and scalability of pilot plants like these as well:

https://techcrunch.com/2022/12/20/porsche-pumps-first-synthe...

With advances in nuclear fusion or other technologies that lower the price of CO2 neutral electricity, we just might be able to build plants that produce conventional fuel, using seawater and removing CO2 from the atmosphere at the same time. This would allow scalable production of conventional fuel, without affecting our drinking water or having to replace several billion cars all over the world.

I’m probably simplifying here way too much, but exciting developments in that space.

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Synthesizing conventional fuel makes a lot of sense for airplanes. But the overall efficiency of internal combustion fuel in cars is awful.

Missing out on the potential air quality improvements would be disappointing too.

Fully agree with you on the significant efficiency advantage of electric cars vs. ICE-cars.

There might be several use cases, airplanes is one for sure, given the energy density per kg is too low in batteries vs. kerosene today. Pure hydrogen planes have big risks associated to them.

Potentially not having to drill into the ground anymore to extract oil for fuel production is another one. Producing conventional fuels and plugging them into the existing distribution system is beneficial in terms of how rapidly we could replace CO2-adding fuel with CO2-neutral fuel. The market would take care of this as soon as synthetic fuels are cheaper than “old fuels”. This is especially relevant if you think about the billions of people in the developing world that today cannot afford electric cars or the country doesn’t have the infrastructure to support electric cars. Batteries also still have cons in their production process (extracting lithium for example), and recycling is not solved neither. Again, this might be solved at some point, but scaling existing battery tech today to billions of cars would have its own side effects / feasibility issues.

Another benefit I could think of is we would reduce our reliance on certain countries that own most of the oil, geopolitically a very important factor as well.

Just thinking out loud here. Increasing our odds to potentially produce billions of liters of conventional fuel that might be cheaper than “old fuel” at some point, while taking CO2 out of the atmosphere, sounds promising to me.

> There might be several use cases, airplanes is one for sure, given the energy density per kg is too low in batteries vs. kerosene today. Pure hydrogen planes have big risks associated to them.

Is ethanol biofuel not an option? I imagine that actual production would be the limiting factor but it seems to me that should be a workable solution but would probably require significant retooling and redesigning of engines.

I'd guess we'll be looking at a combination of various fossil fuel replacements in the future. EV's are great, but it'll take up towards a century before combustion engines are a thing of the past.And I suspect that's being optimistic.

I seem to remember (don't have the source anymore, if someone can find it again I'd be grateful) that half of the total fuel produced worldwide is used to litterally take the other 50% to where it's needed. Delocalization of fuel production would be a BIG deal.

What do you mean by "efficiency" here?

Energy efficiency. Electric to gasoline to wheels is probably something like 75% * 50% * 30% == 11% efficient (roughly, very roughly). Electric to battery to wheels is approximately 77% efficient.

We'd need 5 times the power generation capacity, or more, just to support that use case.

The fact that we burn over a million tons of gasoline a day (in the US alone) is a secondary issue, but even by itself that's a hell of an engineering problem to solve. Aviation use is less, but still a lot.

Aha, thanks for clarifying; now I see what you mean. I'm not used to thinking about gasoline as something we spend electricity to produce!

It should be said that the overall efficiency of airplanes is also terrible. It's just that there's no drop-in replacement, and therefore people are looking at e-fuels for planes. But this doesn't change a simple fact: This is very inefficient and won't be cheap.

This seemed ... odd. Surely being crammed in like a cow in an abattoir truck gets airplanes something. So I looked it up https://en.wikipedia.org/wiki/Energy_efficiency_in_transport

For the curious: Boeing 747-400: 3.1 litres / passenger 100km, or 91 passenger miles per US gallon.

Better than ICE car with 1 person in it, and modern planes do better. It turns out the lower temperatures at 10km above sea level helps both the Carnot efficiency and drag. But the 747-400 travels just under the speed of sound, which hurts. Slower airplanes (but still faster than any land based transport), get you a 2 or 3 fold improvement.

Ironically we don't produce enough CO2 (in concentrated form) to do that on a large scale. This means that we might have to use direct air capture to get the CO2, which is quite expensive. It also begs the question: Since the CO2 is going to end up in the atmosphere anyway, then why go atmosphere -> CO2 -> synfuel -> atmosphere instead of fossil fuel -> atmosphere AND atmosphere -> CO2 -> underground storage. The second might be cheaper and the end result in terms of CO2 in the atmosphere will be the same.

Synthetic fuels will be nothing but greenwashing for the next 20 years: there is massive demand for industrial hydrogen (most fundamentally for synthetic fertilizers), and as long as that demand is not met with hydrogen from renewable sources, it will be supplied (as today) from from methane-steam reforming -- using the exact fossil hydrocarbons that synthetic fuels would replace.

But yes, synthetic fuels would allow people with money to go to Davos and run their yachts while claiming total greenery, so I have a feeling we will end up with green synthetic fuel and black synthetic fertilizers even if causes larger net emissions.

Ironically, as production of hydrogen increases and therefore the availability increases and price drops, more and more industries will want to make use of it, reducing availability as well.

Same with renewable energy; over here, even before an offshore wind park was completed, Microsoft swooped in and bought up its capacity for one of their datacenters.

> even before an offshore wind park was completed, Microsoft swooped in and bought up its capacity for one of their datacenters.

Why is that bad? Isn’t it great that such an investment is so quickly finding a customer?

> advances in nuclear fusion or other technologies that lower the price of CO2 neutral electricity

We are still far from the point where anybody serious could reasonably affirm that advances in nuclear fusion would be expected to lower the price of CO2 anywhere in the foreseeable future.

That does not mean we should slow down R&D in nuclear fusion in any way but rather bet on the fast deployment of renewables if the objective is to lower the price of C02 neutral electricity in the coming decade(s).

You may be interested that Porsche basically dumped that project recently, though it didn't get a lot of media attention.

The current Haru Oni plant is a really tiny pilot plant, but it always came with the promise that it'd be scaled up by many orders of magnitude. Der Spiegel recently reported that the plan to build a large wind farm to power the next stage has been cancelled: https://www.spiegel.de/auto/volkswagen-vw-boss-oliver-blume-... (sorry, paywalled, but I don't have another source)

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