Air to Gasoline Story Starts a Fire

June 10, 2018


Rob Meyer in The Atlantic:

A team of scientists from Harvard University and the company Carbon Engineering announced on Thursday that they have found a method to cheaply and directly pull carbon-dioxide pollution out of the atmosphere.

If their technique is successfully implemented at scale, it could transform how humanity thinks about the problem of climate change. It could give people a decisive new tool in the race against a warming planet, but could also unsettle the issue’s delicate politics, making it all the harder for society to adapt.

Their research seems almost to smuggle technologies out of the realm of science fiction and into the real. It suggests that people will soon be able to produce gasoline and jet fuel from little more than limestone, hydrogen, and air. It hints at the eventual construction of a vast, industrial-scale network of carbon scrubbers, capable of removing greenhouse gases directly from the atmosphere.

Above all, the new technique is noteworthy because it promises to remove carbon dioxide cheaply. As recently as 2011, a panel of experts estimated that it would cost at least $600 to remove a metric ton of carbon dioxide from the atmosphere.

The new paper says it can remove the same ton for as little as $94, and for no more than $232. At those rates, it would cost between $1 and $2.50 to remove the carbon dioxide released by burning a gallon of gasoline in a modern car.

“If these costs are real, it is an important result,” said Ken Caldeira, a senior scientist at the Carnegie Institution for Science. “This opens up the possibility that we could stabilize the climate for affordable amounts of money without changing the entire energy system or changing everyone’s behavior.”

Here’s where it got sticky.
Ken Caldeira is a real, highly regarded scientist, and a lot of people thought this quote which seems to unreservedly endorse the new science seemed a little overly enthusiastic.

One scientist said Caldeira’s statement “..will leave you scratching your head.”

Many pointed out that there was insufficient info to say just how this tech would pencil out, and overly optimistic projections of as-yet-undemonstrated carbon capture technology are used by climate deniers and delayers to justify slow walking on renewables and efficiency.

Dr. Caldeira apparently heard the questions, and felt he was already being quoted out of context by the usual suspects – he posted Saturday to his blog.

Ken Caldeira

I woke up this morning to read The Federalist quoting me out of context, putting words in my mouth that I did say but wished I had worded more carefully. For those not familiar with The Federalist, they are a right wing think tank who are widely credited for successfully stacking the U.S. Federal Judiciary with right wing judges such as Neil Gorsuch.

The paragraph in question was:

This opens up the possibility that we could stabilize the climate for affordable amounts of money without changing the entire energy system or changing everyone’s behavior,” Ken Caldeira, a senior scientist at the Carnegie Institution for Science, told The Atlantic.

Here is the full email I sent to Robinson Meyer, writer for The Atlantic:


I am no expert in systems costing, but I read the paper as saying that Direct Air Capture of carbon dioxide would cost somewhere in the range of $100 to $250 per ton.

If these costs are real, it is an important result.

If you look at this paper (and this is what I could find quickly on the web)

Carbon prices projected for this century look like this for 2 C stabilization from a business-as-usual scenario:

unnamed (1)

If you notice, by the end of the century, these integrated assessment models project carbon prices of many hundreds if not thousands of dollars per ton CO2.

The IPCC estimated that these levels of carbon prices could shave 5% off of global GDP.

The result of David Keith and colleagues suggest that carbon prices could never go above the $100 to $250 range per ton CO2, because it would be economic to capture CO2 from air at that price.

This suggests that the hardest to decarbonize parts of the economy (e.g., steel, cement manufacture, long-distance air travel, etc) might continue just as they are now, and we just pay for CO2 removal.

To put these prices in context, $100 per ton CO2 works out to about $1 per gallon of gasoline. This suggests that a fee of somewhere between $1 and $2.50 per gallon would allow people to drive their ordinary cars, and we could just suck the CO2 out of the atmosphere later.

This opens up the possibility that we could stabilize climate for affordable amounts of money without changing the entire energy system or changing everyone’s behavior.

To give more context, global CO2 emissions is something like 36 GtCO2 per year. If we were to remove all of that with air capture at $100 per tonCO2, that works out to $3.6 trillion dollars.

Depending on how you count things, global GDP is somewhere in the neighborhood of $75 to $110 trillion. So, to remove all of this CO2 would be something like 3 to 5% of global GDP (if the $100 per ton number is right). This puts an upper bound on how expensive it could be to solve the climate problem, because there are lots of ways to reduce emissions for less than $100 per ton.

In any case, it makes it much easier to deal with the hardest to decarbonize parts of the economy.

Again, this is all with the caveat that I am no expert in costing of engineering systems. But, if this paper is correct, the result seems important to me.


My colleagues and I have been spending a lot of time thinking about how we are to decarbonize the hardest parts of the energy system to decarbonize. We have a paper in press on this very topic, which we expect out later this month.

My positions are fairly well known. In MIT Technology Review, I wrote in 2015:

It is always going to be easier and cheaper to avoid making a mess than to clean up one we have already made. It is easier to remove carbon dioxide from a smokestack, where the exhaust is 10 percent carbon dioxide, than from the atmosphere, which is 0.04 percent carbon dioxide.

In that piece, I went on to write:

When the Constitution of the United States of America was written, it seemed inconceivable that people would be released from slavery or that women would vote. Just a few years before gay marriage became the law of the land, it would have been impossible to predict such a sweeping change in social attitudes. For us to even have a chance of addressing the climate problem, we’ll need another huge change in public attitudes. It will need to be simply unacceptable to build things with smokestacks or tailpipes that dump waste into the air. This change could happen.

The point with my poorly worded quote was not that we don’t need revolutionary changes in our energy system, but that there are some very hard-to-deal-with sources of CO2 emission, like long-distance aviation, that could be addressed by using hydrocarbon fuels coupled with the contemporaneous capture of the CO2 released by devices such as that being investigated by David Keith and colleagues.

As recently as 1 June 2018, I wrote an email to Peter Frumhoff of the Union of Concerned Scientists, urging that organization to put out a statement saying:

Today’s emissions policies should be based on the assumption that most [of] our CO2 emissions will remain in the environment for hundreds of thousands of years. Emissions policies should not be made on the assumption that future generations will clean up our mess using carbon dioxide removal technologies and approaches.

There is a big difference in using direct air capture of CO2 to offset contemporaneous emissions and using direct air capture of CO2 to argue that we can continue emitting CO2 today in the hopes that someone else will clean up our mess in the future.

As a little egomaniacal side note, I would like to point out that Caldeira and Rampino (1990) may be the first paper to point out the approximately 300,000 year time scale for removal of atmospheric CO2 concentration perturbations by silicate rock weathering. This estimate has held up pretty well over the last decades.



What are the lessons learned?

When speaking or writing an email to a journalist, think about how each sentence can be read taken out of context. Even if you trust the journalist to represent your views well (and I think Robinson Meyer did an excellent job), somebody later can take a carelessly worded statement and use it out of context.

Also, we are busy, and when requests come in, we often try to respond with something quickly so we can back to our day jobs (which in my case happens to be scientific and technical research). I should slow down a little bit and take the time needed to write more careful prose.

8 Responses to “Air to Gasoline Story Starts a Fire”

  1. grindupbaker Says:

    So Ken Caldeira joins Jim White and others as “with friends like these who really needs enemies”.

    Per above: Wind & solar panels radiation —> electricity, electricity—>electrolysis for the hydrogen. Add limestone and CO2 —> gasoline.

    Preferred by humans current method alternative: Gasoline —> diesel-powered electrical generator, electricity—>electrolysis for the hydrogen. Add limestone and CO2 —> gasoline.

    Other scientists claim to make gasoline from coal at 1:3 so humans could do coal —> gasoline—> coal and never run out of coal if they could just make coal from gasoline.

    It’s always fun creating energy in the Universe without destroying mass. I know it’s energy density, I understand batteries and hydrogen economy, don’t tell me. I just think humans are much predictable.

    • dumboldguy Says:

      I have a college-educated friend, a former Air Force officer who spent his time in missile silos out west and a great guy in all respects. He firmly believes that one day we will figure out how to get the energy our of coal without burning it and releasing carbon dioxide. Unlimited energy for millennia, he says.

      • grindupbaker Says:

        Energy from coal without burning it is not inane per se but I can’t assess that much because I never thought about it. It’s all simple in concept, C + O2 is an exothermic reaction. It just happens to be a nuisance that the product is a gas. If carbon can be combined with a chemical to produce a solid or liquid and it’s exothermic then it’s practicable for generating electricity, but I assume it’s not known whether practical yet, practical being such as what’s the cost of mining and moving the other material, what’s the cost of disposing of the “waste” product, what’s the cost of the plant for the process, and so on (the essential basis is “energy density”).

        I think the bottom line on that practicality based on humans being this species and not a fictional one is if C + —> solid/liquid + energy can be done for cheaper than 100.0001% of the “cost” (human money thing) of C + O2 = CO2 + energy then it’ll become primary like your former Air Force officer buddy says.

        Climate scientists use 4,000 GtC recoverable (unless clathrates are recoverable). EIA is 986 Gtc (from vague memory), GACC is >10,000 Gtc so millennia is out of the question unless GACC best assesses the shenanigans of the various governments and their agencies that report their recoverables.

  2. dumboldguy Says:

    Excellent, excellent post. Enlightening on many levels.

    (And sell your Solar Roadway stock so you can invest in Carbon Engineering. That’s if you haven’t already sold it and invested in the Boring Company and its tunnels and flamethrowers)

  3. Gingerbaker Says:

    In related news, The City of New York is offering you you you ownership of the Brooklyn Bridge for one low monthly payment!

    And I am a Nigerian tribal king who wants to pay you you you a lot of money if you will take over my stolen bank account funds.

    Don’t worry, the check is in the mail.

  4. renewableguy Says:

    basically we have to carbon capture in some form to stay ahead of the thawing of northern land masses. As the thaw line moves northward, we will get co2 and ch4 in increasing amounts per year as time moves on.The task ahead is to produce no co2 in wastes and to remove co2 from the atmosphere anyway. It is monumental in scale and no one wants to start really doing this yet.

    Better yet electrify all we can and leave what little is left hopefully to biofuels.

  5. Sir Charles Says:

    I think the whole story is a pipe dream. Burning carbon (hydrates) to CO2 is an exothermal reaction. So you would need at least the same amount of energy to (re)transform the CO2 – which you first have to capture – into carbon (hydrates) again. So how do you want to source this energy carbon neutral? Do they want to use sunlight and algae? Perpetual motion machines don’t exist yet.

    In terms of price a ton of coal produces 2.8 tons of CO2…

    Nagh. I’m yet sceptical of CCRt. We need to get emissions down to zero in the next two decades. That’s for the 2°C target.

    • grindupbaker Says:

      Well yes, obviously, as I’ve already described above. The purpose would be energy density (cannot fuel aircraft by a coal fire, too heavy). The carbon capture part only happens if its energy source is nuclear, hydro, wind, solar and tide.

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