Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Sunday, January 8, 2017

Carbon capture finally cracked? Why you can't fight climate change with Coke or Pepsi

From "", an article by Julian Turner. Not wrong, is it possible that we can't discuss anything any longer without turning it into a "game changer", a "breakthrough" and all the rest? A little less hype in these reports would help a lot. 

Some time ago, I found myself trying to explain to a journalist why I opposed CO2 mining in Tuscany. I said something like, "it makes no sense that the regional government spends money to reduce CO2 emissions and, at the same time, allows this company to extract CO2 that, otherwise, would stay underground." "But", the journalist said, "I have interviewed the people of this company and they say that the CO2 they extract is not dispersed into the atmosphere - it is stored." "And where is it stored in?" I said. "They sell it to companies that make carbonated drinks." I tried to explain to him that producing Coca Cola or Pepsi is not the way to fight climate change, but I don't think he really understood.

This is typical of how difficult is to make some messages pass in the public debate. Among the many possible ways of mitigating global warming, carbon capture and sequestration (or storage) - CCS - is the least understood, the most complicated, and the most likely to lead to pseudo-solutions. Not surprising, because it is a complex story that involves chemistry, geology, engineering and economics.

About one month ago, a post by Julian Turner appeared on "Power Technology" with the rather ambitious title of "Carbon Capture Finally Cracked." The post is full of hype about a breakthrough in the process that purifies CO2 at the output or a coal-burning plant - a process called "CO2 scrubbing".  The new process, it is said, is better, less expensive, faster, efficient, and  "game changer". Mr. Sharma, CEO of the company that developed the process declared:

“TACL will be able to capture CO2 from their boiler emissions and then reuse it,” confirms Sharma. “For the end user the electricity produced by capturing carbon dioxide will be clean electricity and the steam produced will be clean energy. For that reason, we can say that it is ‘emissions-free’.”
I have no doubt that there is something good in the new process. Scrubbing CO2 using solvents is a known technology and it can surely be improved. Technology is good at doing exactly that: improving known processes. The problem is another one: is it a really an "emission-free" process? And the answer is, unfortunately, "not at all", at least in the form the idea is presented.
The problem, here, is that all the hype is about carbon capture, but there is nothing in these claims about carbon sequestration. Indeed, the article discusses "carbon capture and utilization" (CCU) and not "carbon capture and sequestration" (CCS). Now, CCS is supposed to mitigate global warming, but CCU does NOT.

Let's go back to basics: if you want to understand what CCS is about, a good starting point is the 2005 IPCC special report on the matter (a massive 443-page document). More than ten years after its publication, the situation has not changed very much; as confirmed by a more recent report. The basic idea remains the same: to transform CO2 into something that should be stable and non-polluting. And when we say "stable" we mean something that should remain stable for time spans of the order of thousands of years, at the very least. This is what we call "sequestration" or "storage".

A tall order, if there ever was one, but not impossible and, as it is often the case, the problem is not feasibility, but cost. The safest way of storing CO2 for very long times is to imitate the natural process of "silicate weathering" and transform CO2 into stable carbonates, calcium and magnesium, for instance. It is what the ecosystem does in order to regulate the temperature of the planet. But the natural process is extremely slow; we are talking about times of the order of hundreds of thousands of years; not what we need right now. We can, of course, accelerate the weathering process but it takes a lot of energy, mainly to crush and pulverize silicates. A less expensive method is "geological storage", that is pumping CO2 into an underground reservoir. And hope that it will stay there for tens of thousands of years. But it is the main aim of CCS, nowadays.

This said, the way to evaluate the feasibility and the opportunity of the whole concept of CCS is to examine the life cycle of the whole process; see how much energy it requires (its energy return for energy invested, EROEI), and then compare it with the data for alternative processes - for instance investing the same resources into renewable energy rather than in CCS (and renewable energy may be already less expensive than coal produced electricity). But it seems that this comparative analysis has not been done, so far, despite the several cost analysis performed for CCS. One thing that we can infer from the 2005 report  (see page 338) is that, even without scrubbing, the energy necessary for the whole process might be not so far away from values that would make it an exercise in digging holes and then filling them up again, as John Maynard Keynes is reported to have proposed. The situation is better if we consider geological storage, but even in this case scrubbing is only a fraction of the total cost.

At this point, you can understand what's wrong in calling the new scrubbing process a "game changer." It is not that. It is a process that improves one of the steps of the chain that leads to carbon storage, but that may have little value for CCS, unless it is evaluated within the whole life cycle of the process.

Then, in the whole article by Turner, there is no mention of CCS/storage. They only speak of carbon capture and utilization (CCU) and they say that the CO2 will be sold to another company that will turn it into soda ash (Na2CO3). This compound could then be used it for glass making, urea making, and similar purposes. But all these processes will bring back the captured CO2 to the atmosphere! No storage, no global warming mitigation - they might as well sell the CO2 to the industry that makes carbonated beverages. This is not the breakthrough we need.

So, what sense does it have to make so much noise about "clean energy," "clean electricity," and "emission-free" energy when the new process aims at nothing of that sort? Not surprising, it is all part of the "fact-free" ongoing debate.

To conclude, let me note that this new scrubbing process might just be one of those ways of "pulling the levers in the wrong direction," according to a definition by Jay Forrester. That is, it may be counter-productive for the exact purposes it had been developed for. The problem is that pure CO2 is an industrial product that has a certain market value, as the people who extract it from underground in Tuscany know very well. So far, the cost of scrubbing has prevented the exhaust of fossil-fueled plants from having a market value, but a new, efficient process could make it feasible to turn it into a saleable product. That would make coal plants more profitable and would encourage people to invest into building more of them, and that would generate no reductions in CO2 emissions! It would be even worse if the coal industry were to sell to governments their scrubbing process in order to escape carbon taxes. So, you see? Once more, the rule of unintended consequences plays out nicely.


  1. In the US, almost 70% of fossil fuel is used in ways that are not amenable to carbon capture. Most oil is used in transportation and most natural gas use is for space heating and uses other than electrical generation. If all coal and natural gas power plants were outfitted with carbon capture technology, it would capture only a little more than 30% of the carbon now being released by fossil fuels.

    That said, a reduction of 30% of CO2 emissions would be significant. But as you indicated, all that reduction is dependent on long term storage. Since the volume of liquid CO2 leaving a coal power plant would be almost three times the volume of the coal going in, I can just imagine the expense of shipping that volume away or the expense of injection wells surrounding the power plant (in the happy event that the site was suitable for injection).

    CCS sounds good, but until there is a very high carbon tax, what little CCS there could be will never be economically competitive with conventional fossil plants. And if there were such a tax, fossil fuels wouldn't be competitive with renewables. CCS is a non-starter.

  2. Good article. I certainly expect to see a lot of bogus ways to make coal "clean" as we move forward. I have a big concern with the geologic storage that I've never seen addressed. How can we be sure or ensure that the CO2 stays in the ground? And what happens if we go "all in" on geologic storage and a hundred years from now it's all leaking out? I will be dead, of course, but I'd like to think that whatever we do won't further burden the future occupants.

  3. The same goes, I am sad to say, for energy efficiency in many applications. The more efficient a process is, the higher the per-unit energy costs it can handle. That, in turn, means greater reserves of fossil fuels are profitable to extract. So what is great from a local and limited perspective can be problematic from a whole systems perspective.

  4. Ugo
    All very worthwhile points!
    Its a while ago, circa 2010, but an analysis for the UK Claverton Energy Group put it this way: "While climate change makes burning coal without carbon capture increasingly unjustifiable, this not yet mature technology is projected to need at least 20 – 30 per cent extra coal to be burned. On balance, we judge the UK would be best advised to develop an exit strategy and to move on from coal (soon, almost entirely imported)."


  5. If carbon capture replaces extracting CO2 from stable places, then it will be doing some good at least. We should be campaigning on all fronts, not only to keep fossil fuels in the ground, but also to prevent natural CO2 stores like limestone being used in ways that release the CO2 into the atmosphere.

  6. Hi, Ugo! The tragedy of the modern world, where 'solutions' are sold that actually exacerbate a problem.


  7. Carbon sequestration *does* seem to be hard to understand. I found that I didn't understand it myself until I began reading the first chapters of a textbook on the Cambrian Explosion this past month.

    I'm still struggling to understand how carbon can get oxidized and sequestered (and how that interacts with carbon isotope ratios, organic and inorganic carbon, and so on).

    Combine that difficulty with the irresistible urge to indulge in wishful thinking that seems to dominate most people's thinking, and I'm not sure many journalists would have a chance of understanding carbon sequestration.

  8. The snake oil salesmen just keep it coming. Alge for fuel, electric cars, jet packs, world peace...all those broken, implied promises. Hard to believe anything.



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)