Directly converting CO2 into a gasoline fuel (2017)

https://www.nature.com/articles/ncomms15174

51 68 4 years ago

Fascinating.

Can anyone spot how efficient it is? It declares that it's "Highly efficient", but then no details on what the actual efficiency is.

danieldbird• 4 years ago

And then put it back in the ground, or burn it again..?

jokoon• 4 years ago

Yes, it doesn't make sense. Where would the CO2 come from? Capturing CO2 is not a proven technology.

Or maybe cars would be equipped with a tank that compresses CO2, but even then.

It's funny how the solution is all about stopping to use fossil fuels, but people still find ways to CREATE fossil fuels.

bartwe• 4 years ago

Wondering if this could be combined with solar peaking to buffer summer overcapacity till winter time.

5ersi2• 4 years ago

So this process is "CO2 hydrogenation" meaning that it needs elemental hydrogen, which is not naturally available (except in trace amounts). To make this work one needs to first produce hydrogen which is itself an energy consuming process.

So basically, we'd burn fossil fuels producing CO2 and then reverse this process via "CO2 hydrogenation" (with significant losses) to again get the hydrocarbons (aka gasoline) ?

This whole thing would only make sense if we had abundant source of elemental hydrogen. But then why burn fuel in the first place.

(This would only make sense if all fuel totally ran out and then we'd need this process to make hydrocarbons for material use: plastics, etc..)

pfdietz• 4 years ago

The energy has to come from somewhere.

mlatu• 4 years ago

yes, and it is our duty to think about where we lose it and how not to.

ben_w3• 4 years ago

Can also make sense if this is cheaper than batteries.

Electrolytic hydrogen is so easy I did it when I was nine years old — the only reason I powered the reaction using a battery instead of PV was that back in 1992, PV wasn't something a kid could easily get hold of with pocket money.

gefhfffh4• 4 years ago

Well, short term it may be cheaper. Long term you are going to pay, because the efficiency is horrible, 10-30% depending on who u ask

masta• 4 years ago

Not to mention that it requires capturing and probably liquifying the CO2 first, which is also energy intense. If we do CO2 Hydrogenation, it will be for Methane gases, not liquid. Methane is easy to store, has rather flexible uses and would help in keeping the grid stable.

Liquids, especially when used in ICE engines later on, would result in an energy efficiency of 5-10% max. This is abysmal and we could use that otherwise wasted energy to decarbonize many other things by directly electrifying them.

H8crilA3• 4 years ago

https://en.m.wikipedia.org/wiki/World_energy_supply_and_cons...

It is hilarious how many people think the problem is with reversing the CO2 creation. No, it's a matter of getting the joules to sustain the modern lifestyle and the population count.

CPLX• 4 years ago

Primary energy assessment follows certain rules[note 1] to ease measurement of different kinds of energy. These rules are controversial. Water and air flow energy that drives hydro and wind turbines, and sunlight that powers solar panels, are not taken as PE, which is set at the electric energy produced. But fossil and nuclear energy are set at the reaction heat which is about 3 times the electric energy. This measurement difference can lead to underestimating the economic contribution of renewable energy.[7]

Seems relevant

iso12102• 4 years ago

That says global 'consumption' is about 80000 TWh a year. Incoming solar energy is about 1700 times that

bryanlarsen• 4 years ago

Why do this? Because we don't have electric or hydrogen airplanes yet, and it takes forever to approve an airplane and for it to become widespread.

Even if it is only 10% efficient, some form of carbon capture is going to be required to hit carbon zero. This is one of the most promising mechanisms for carbon capture.

bregma• 4 years ago

What if you had massive amounts of virtually free energy just falling out of the sky in one or a few isolated locations, but only for a few hours every day, and your consumption patterns required an available-24-by-7 safely transportable consumer-safety-level supply?

Carbon-hydrogen bonds are an relatively efficient and safe way of storing energy and we have well-developed technology and infrastructure in place to take advantage of that.

chii• 4 years ago

This whole thing would only make sense if we had abundant source of elemental hydrogen. But then why burn fuel in the first place.

water is an easy elemental source of hydrogen. If it is possible to fuel this electrolysis via cheaply obtained renewable energy, then it makes a lot of sense to produce fossil fuels using this method - it will allow the existing infrastructure to consume such produced fuels, so you save capital and energy on replacing them.

danuker2• 4 years ago

Absolutely. Look at intraday electricity prices, and you see that the energy is cheapest when the sun is shining.

Problem is, if you use it for cooling, it's strictly better to use the electricity directly (chances are the sun is shining when it's hot).

And if you use it for heating (at least from day to night), the round-trip efficiency is probably still better for batteries, or electric heating + hot water storage, because you can use heat pumps which are say, 5x more efficient than burning fuel.

kingkawn• 4 years ago

Why not use that electricity to power electric motors instead tho

5ersi2• 4 years ago

water is an easy elemental source of hydrogen.

Sorry but this goes against the definition in elemental form (in this case it's H2).

Also there is no such thing as `cheaply obtained renewable energy`. If it was your electricity bill would be 0.

Gravityloss2• 4 years ago

Hydrocarbon fuels are a lot more energy dense than batteries or hydrogen (with tankage), so they are needed for things like long distance flight for now.

enrgtw2022• 4 years ago

Yep.

Batteries aren't great for super-cold areas. Pure hydrogen, my understanding is that it's pretty much impossible to make a 'leak free' tank. So for things like backup power generation there is an additional challenge. More thinking about need to top off than risks, I'm not qualified to speak to whether such a tank would be a risk.

dahfizz3• 4 years ago

They also make for great storage. Using solar to make a hydrocarbon fuel which is turned into electricity in our existing fossil fuel infrastructure seems way more plausible than spending trillions on batteries or pumped hydro.

jiri2• 4 years ago

stored hydrocarbons are way more easy to handle than stored h2. On top of that, h2 is hard to contain, it can leak everywhere.

londons_explore• 4 years ago

It's a shame that currently there is no economic incentive to use such tech, even if it was 100% efficient.

It's always cheaper to use oil from the ground than it is to use another power source to manufacture oil.

gefhfffh4• 4 years ago

It's cheaper, but the costs are external costs (calculated for the next 100 years about 600 Euro per ton of emitted CO2).

They could be internalized by CO2 pricing, such as CO2 tax or certificates

throwaway0a5e• 4 years ago

Fossil fuels are cheaper because nature did the energy intensive "turn dinosaurs into oil" part (i.e creating the hydrocarbon molecules) for us over the span of millions of years and we just extract it from the ground and do some chemistry magic to make it into useful stuff.

The "create the useful hydrocarbon out of atmospheric carbon" step needs to necessarily be cheaper than getting dead dinosaurs to a refinery and refining them.

Screeching about externalities adds nothing to the discussion. Burning synthetic hydrocarbon fuel would also release carbon. A CO2 tax would hit it just as hard as it hits traditional hydrocarbon fuels unless you do stupid "craft the tax to pick and choose winners" crap that a carbon tax is explicitly supposed to avoid.

john567• 4 years ago

Elon Musk once pointed to the low energi state of CO2 as a problem meaning it doesn't react with other things without additional energy added. This makes carbon capture fundamentally hard and anyone claiming otherwise is either in possession of some infinite power supply or we live in a post scarcity society.

Either way, planting trees appears to be a good mechanism for carbon capture. So go do that instead!

JoeAltmaier• 4 years ago

One step better: don't create it to begin with. Use electric devices instead.

gbear605• 4 years ago

Some activities are much more difficult to do with electricity because of the weight of batteries or because the environment is cold, flying planes or existing in Arctic climates being the most notable. So if we want a totally carbon-neutral world while still being able to do everything we can today, some carbon capture is important.

Hopefully we’ll have a huge innovation in batteries, but oil is very energy dense and some burning seems likely for a long time. We also will probably want to reduce CO2 levels from wherever we peak, even assuming we’re not burning any more oil, so carbon capture is important for that too.

Now some of that carbon capture can be in the form of well managed trees, but they take up a lot of land and you have to chop them down and store the wood somewhere that it won’t break down, and that becomes its own storage problem.

ZeroGravitas4• 4 years ago

If this worked, then you'd still need it to be better than using the money expended to offset other other fossil carbon usage, one means of which could be converting gasoline using processes to use electricity directly.

As a result, I don't think this can ever make logical sense under any circumstances, very similar to carbon capture attached to fossil fuel generators. It just doesn't pencil out, even in theory.

Basically, gasoline isn't a particularly good fuel unless society is letting you dump the pollution for free, in which case it still isn't particularly good, but some other sucker is paying the price for it. And that other sucker is often you.

fsh6• 4 years ago

Hydrocarbons are fantastic fuels when high energy density is required. In fact, airliners would be completely impossible without them. Even the most fantastic experimental batteries have nowhere near enough energy density for efficient powered flight. There are some plausible concepts for hydrogen powered planes, but those waste a lot more space on fuel tanks compared to hydrocarbon powered ones.

Synthetic hydrocarbons will probably remain the only option for carbon-neutral long-distance travel in the foreseeable future.

ZeroGravitas4• 4 years ago

Simply offsetting the carbon, by replacing fossil fuel uses in other sectors, makes more financial/economic/practical sense than creating synthetic hydrocarbons to greenwash your own specific usage. People really are stuck in a fossil-fuel mindset when the real solution is to stop using them as fast as possible. A simple carbon fee does this without much fuss. People peddling synthetic hydrocarbons are, again like carbon capture and storage attached to fossil fuel generators, simply bullshitting. They might as well claim to be transitioning to perpetual motion powered flight that they have working today at lab scale. Because, basically that is what they are saying.

PaulHoule4• 4 years ago

It doesn’t make sense for cars (electricity is a practical alternative and if you wanted to use chemical fuels you would synthesize methane or 1-butanol, dimethyl ether or some other single-entity fuel for which the production process can be optimized)

Aviation is 30-40 years behind in fuels (they still use leaded gas.). The kind of Fischer-Tropsch chemistry that these guys are messing with has been basically abandoned for automotive use but is still being pursued for jet fuel because they are afraid to use any fuel which isn’t identical to existing fuels in composition…

Traditionally these processes start with a stream of hydrogen and carbon monoxide which can be made from coal or methane, the economics are gawdawful because the reactions that build up hydrocarbons and break them down have to be closely balanced —- polyethylene formation can be explosive, methane forms quickly if the temperature is too high. What it means is you have a big machine (high capital cost) that makes just a trickle of fuel. In the green era people like these guys are mixing up the chemistry so you can put CO2 in instead.

I have been thinking about how you would make plastic membranes from asteroid materials, we think some asteroids have something that is basically coal and the head end would turn that into ‘petrochemicals’ and might have a lot in common with fuel synthesizers… A lot of chemical processes will create waste CO2 which is precious in that context and has to be recycled.

cjrp• 4 years ago

Aviation is 30-40 years behind in fuels (they still use leaded gas.).

In small aeroplanes yes, I don't think Jet-A has lead in though.

NovemberWhiskey2• 4 years ago

The only place aviation uses leaded gas is in the small, piston engine part of the market that represents primary training or hobbyist/personal transportation flying. In those cases, it's more like engine designs are 70 or 80 years behind current designs; and oftentimes the actual aircraft are not much younger.

There's no lead in jet fuel, and I'm just not exactly sure what you mean by aviation being "behind" in fuels in that respect. What's the leading edge supposed to be, in gas turbine technology, other than essentially kerosene?

jiri2• 4 years ago

.. you would synthesize methane or 1-butanol, dimethyl ether or some other single-entity fuel ...

I agree that simple fuels makes more sense to synthesize. Methane is simple, but way more difficult to handle than gasoline. 1-butanol and other liquids would be great, but it is not so easy to produce in scale yet, I believe.

Directly converting CO2 into a gasoline fuel (2017)

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