ChatGPT & DALL-E generated image of panoramic image of an air to fuel plant, creatively reimagined to emphasize inefficiency and Rube Goldberg-like complexity.

Chevron’s Fig Leaf Part 6: Carbon Engineering’s Air-To-Fuel Plan Is Even Worse

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Carbon Engineering recently garnered $68 million in investment in its air-carbon capture technology from three fossil-fuel majors. This is part 6 of the 5 article series assessing the technology and the value of the investment. Yes, a 6th and 7th were tagged on, because the story just gets worse.

Screens shot of official Canadian federal website and $7,893,609 CAD for Carbon Engineering
Screens shot of official Canadian federal website and $7,893,609 CAD for Carbon Engineering

The first piece summarized the technology and the challenges, and did a bottoms-up assessment to give context for what Carbon Engineering is actually doing. The second piece stepped through Carbon Engineering’s actual solution in detail. The third piece returned to the insurmountable problem of scale and dealt with the sheer volume of air that must be moved and the scale of machinery it has designed for the purpose. The fourth article looked at the market for air carbon capture CO2 and assessed why three fossil fuel majors might be interested. The fifth article looked at the key person behind this technology and the expert opinions of third parties.

But a couple of commenters along the way kept asking the same question:

Why was I talking about use cases that weren’t the one Carbon Engineering had been claiming recently: an air-to-fuel scheme which would combine the barely carbon positive CO2 from the system they’ve been designing for years, and hydrogen from water using a bunch of technology that they were going to bolt on but had  zero papers published on?

Air-to-fuel being even less sensible than making hydrogen from electricity at industrial scales, I’d seen it and dismissed it, preferring to dig into the actual underlying papers rather than the press. But after explaining myself in comments for the third time, with references and quotes, it became apparent a follow-on piece was needed.

This sixth piece assesses what Carbon Engineering’s claims are related to air-to-fuel. The seventh and likely final article will do an energy, CO2, and cost comparison between Carbon Engineering’s technology compared to just putting electricity into cars.

What are the published claims?

From the Canadian federal government page with the screenshot above.

Building on a successfully demonstrated prototype pilot that can capture 1 tonne of atmospheric carbon dioxide per day, a hydrogen production and fuel synthesis platform will be integrated into this prototype, which will form an “air to fuels” prototype system.

From a 2018 National Geographic profile on Carbon Engineering.

Still, even at $100 per ton, there aren’t enough CO2 buyers right now. So the company decided to make a carbon-neutral liquid fuel, said Steve Oldham, CEO of Carbon Engineering. […] The captured CO2 is combined with hydrogen, which is made through the electrolysis of water. While the process requires a lot of electricity, the pilot plant in Squamish uses renewable hydro power. The resulting synthetic fuel can be blended or used on its own as gasoline, diesel, or jet fuel. When it’s burned it emits the same amount of CO2 that went into making it, so it’s effectively carbon neutral.

From Carbon Engineering’s own website.

CE’s AIR TO FUELS™ technology provides a tool to significantly reduce the carbon footprint of the transportation sector by recycling atmospheric CO₂ into liquid fuel and displacing crude oil. It gives an ability to harness low-carbon electricity such as solar PV, and material inputs of water and air, to generate fuels that are drop-in compatible with today’s infrastructure and engines.

From the 2018 paper:

variant ‘‘D’’ is optimized to provide CO2 for fuel synthesis. CE is developing air-to-fuel systems in which the hydrogen required as feedstock for the fuel synthesis step is produced by electrolysis. In this configuration, the oxygen from electrolysis is sufficient to supply the DAC plant, so in this application we drop the ASU from the DAC process. The fuel synthesis system requires a CO2 supply pressure of 3 MPa, reducing the cost and complexity of the CO2 compression and clean up. CE is developing methods to integrate the DAC and fuel synthesis, but for simplicity of analysis, here we show (Table 2) the inputs for a plant that receives O2 and produces atmospheric pressure CO2.

What does this suggest?

As a reminder, the CO2 that it was capturing in its primary process in both papers was one-third new CO2 from natural gas, which had an upstream efficiency loss. After I published part 2 of this series, Mark Jacobson tweeted about it and pointed out that the actual efficiency was worse than I had asserted. The plant actually would emit almost 3/4 of a ton of new CO2 for each ton actually captured from the air.

Of course, the company captures the CO2 from burning the natural gas as well, ending up with 1.46 tons of pure CO2 for every ton captured from the air in its primary process. If that were bonded into a liquid hydrocarbon and used as transportation fuel, that 0.73% is just emissions in the end. Assuming it produces 1.46 MTons per year and 0.48 Mtons of that comes from the natural gas, if it used solely gas for power and Jacobson’s numbers are assumed to be correct, every ton of CO2 it produced would be effectively 50% new CO2 from the natural gas.

However, its 2018 paper has a purported optional configuration for air-to-fuel with a lower ratio. If I understand its Table 2, every ton of CO2 captured from the air in its air-to-fuel configuration has 0.3 tons of CO2 from natural gas added. Given upstream processing and the full carbon accounting, this suggests that we could use the ratio from its claimed 0.48 to Jacobson’s 0.73. That gives a full carbon debt of 0.35 tons CO2 from natural gas in every ton of CO2 delivered. However, that might not account for the electricity, which as part 1 pointed out, is very good in BC at 15.1 grams CO2e / kWh. The CEO claim of clean hydropower is mostly accurate for BC as that is the primary grid generation source. The 77 kWh then turns into another 0.001 tons of CO2, which is immaterial at this point and we can assume is included in Carbon Engineering’s claimed 0.3 tons.

It’s interesting to read the new CEO saying that there were no big markets for CO2, as this series has shown the big market is pumping it underground to get more oil. That’s what part 4 covered, showing that it was achieving roughly 0% improvement end-to-end when the resultant oil was burned. The workup of use cases didn’t include air-to-fuel as it obviously had a broken air/water-to-wheel cost, efficiency, and emissions profile.

Lastly, the Canadian government’s funding is disappointing. Apparently no one pointed to all of the various previous attempts from organizations which proved that this doesn’t work economically, or did any of the rather basic assessments performed for this series, before handing over close to $8 million CAD (about $6 million USD). Not money well spent, redoing work previously done in a less carbon-neutral way. Especially when the fossil fuel majors were signing checks 10x the size.

Let’s look at the technology

At heart all the company is doing is making a hydrocarbon fuel out of … umm… hydrogen and carbon atoms. It is going to make a ‘carbon-neutral liquid fuel’, per the statements, and has not published any clear statement about what it is making. It’s not diesel or gasoline presumably, but a synthetic precursor or additive to fossil fuels with hydrogen and carbon that burn nicely.

Here’s the thing about liquid fuels. Most of them aren’t only hydrocarbons. The list of things you can make only with carbon and hydrogen — methane, ethane, ethene, ethyne, propane, propene — are notable by mostly being gaseous at room temperature and pressure, not liquids.

Let’s take gasoline, abbreviated to gas and the source of much confusion in North America.

The bulk of typical gasoline consists of a homogeneous mixture of small, relatively lightweight hydrocarbons with between 4 and 12 carbon atoms per molecule (commonly referred to as C4–C12). It is a mixture of paraffins (alkanes), olefins (alkenes) and cycloalkanes (naphthenes).

It’s a chemical soup. One of the nice things about synthetic fuels is that they typically don’t have anywhere the extraneous molecules naturally occurring hydrocarbons have, so you can make a cleaner burning fuel.

What is the company likely making?

It is probably making a simple alcohol-family hydrocarbon, perhaps ethanol which has a chemical formula of C2H6O, is fairly easy to manage, and already works as a gasoline additive. The company might also be synthesizing butanol, which basically just has a lot more carbon and hydrogen atoms, or something else relatively simple. The reference it called out from 1965 talked about synthesizing methanol, CH3OH, using nuclear power. There are substantial downsides to methanol given toxicity and a global market of only 20 million tons, mostly controlled by Methanex out of Vancouver (more on this later). There are also existing methanol-to-fuel processes, as this has been tried many times before and found wanting. For the purposes of this analysis, we’ll assume methanol, as it is the simplest and there’s local expertise with methanol handling and shipping in BC.

There are many ways to create hydrocarbon-based liquids. As it is unstated and as Carbon Engineering has published exactly zero papers on liquid fuels or hydrogen creation that I was able to find, methanol is probably as good as any to use.

What is the energy & CO2 cost of this?

I’m going to try tackle this a few ways. One way is a pure energy perspective. Another will try to assess carbon load. I’ll probably try to figure out a likely cost per liter of the fuel as well.

We’ll start with a ton of CO2 with the alternative of 5.25 GJ of gas and 77 kWh of electricity, which the paper indicates is the air-to-fuel configuration. For the sake of comparisons as we go through, we’ll convert the total energy into MWh for each component to do a build up and as we found in part 2, 3.6 GJ is equal to 1 MWh. That means the CO2 process for air-to-fuel has an equivalent of about 1.54 MWh. The paper’s claim is O&M costs of $23 USD per ton of CO2, with a levelized cost of $94-$130 USD per ton for this process. We’ll use the $112 average for the cost workup.

That’s the workup for the first part of the Carbon Engineering’s air-to-fuel claims. It is planning to build transportation fuels by combining its expensive CO2 with hydrogen which it will get via electrolysis. We are assuming that the company will make the simplest alcohol, methanol. In part 7, we’ll look at the chemical process and make some assumptions for the hydrogen and methanol processes. Then we’ll start comparing them to just using the input energy directly, and what else the money might be able to do.


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Michael Barnard

is a climate futurist, strategist and author. He spends his time projecting scenarios for decarbonization 40-80 years into the future. He assists multi-billion dollar investment funds and firms, executives, Boards and startups to pick wisely today. He is founder and Chief Strategist of TFIE Strategy Inc and a member of the Advisory Board of electric aviation startup FLIMAX. He hosts the Redefining Energy - Tech podcast ( , a part of the award-winning Redefining Energy team.

Michael Barnard has 707 posts and counting. See all posts by Michael Barnard