A Hoover for atmospheric CO2

June 22, 2015 |

1433968584469Why not reduce atmospheric CO2 by capturing it? Why pay $500-$1000 per ton to reduce CO2 via electric cars, if you could pay 80% less via a direct capture of greenhouse gases.

Can it succeed? How, when, and how much? The Digest investigates.

In western Canada a technology is under development that its developers say can reduce the cost of recovering CO2 directly from the atmosphere to $150-$200 per ton in the 2010s, and ultimately they believe to $100 per ton.

Let’s put that in perspective. It costs a consumer $919 to avoid one ton of carbon (compared to using baseline 2005 gasoline) by investing in a Prius running typical E10 fuel blends, and running it for 100,000 miles. Or, $470 per ton, by making the investment in an all electric (in this case, the Nissan Leaf). You can see the math on all that, in “How Do I Save $$ and Save on CO2”, here. 

So, when a technology comes along that can pull already-emitted CO2 from the atmosphere at substantially lower figures, it evokes attention.

That’s the story of Carbon Engineering, based in Calgary. It’s received press coverage for nearly seven years from major media outlets such as the New York Times, Fortune and NPR.

But promise in the lab is one thing, and technical readiness is another thing. The news this year is that the company is now installing a demo-scale air carbon capture system just north of Vancouver, British Columbia in the town of Squamish, on the road to the Whistler ski resort.

Here’s how it works

“We start with a big air contactor,” explains Geoff Holmes. “It’s a liquid medium, rather than a solid state system, and we use potassium hydroxide, which has an affinity for CO2, to remove 70-80% of the CO2 from the air we process, producing potassium carbonate.

“Through what we call a pellet reactor, we have carbonate and calcium ions meet, and we precipitate out calcium carbonate, which comes in the form of little beads, like pearls, and we sluice out the beads which embody the CO2.

“Once we have drained the liquid, we introduce them into a fluidized bed where our jostling bed of beads combusts with natural gas that we introduce at this stage, and with oxygen. When they combust, they naturally decompose into calcium oxide and CO2, and when we mix in a combustion chamber with combustion CO2, we get water vapor and CO2 and the calcium oxide goes back to the pellet reactor, meets the potassium carbonate and does that ion swap. So we close the loop and recover the potassium and the calcium – otherwise we would have to buy and dispose of huge quantities of both.”

“The simplest way to think of it is a black box that takes in natural gas and air and produces a pure CO2 stream that we capture. The natural gas provides the heat and power that drives the system. We can sequester the CO2, or provide it for commercial uses such as for enhance oil recovery systems where it is injected into wells, or to make zero-carbon fuels using organisms that utilize CO2.”

You can read more about the system via this 2012 patent.

The technology classes of carbon reduction

Air carbon capture is a dramatically direct way of fighting climate change, and as a technology stands in stark contrast to the two most popular classes of low-carbon technologies, which are avoided carbon-avoidance, and carbon capture at a point source.

The former uses renewable energy or biobased chemicals or materials in all their myriad forms — from an electric car to using biodiesel, the idea is that we aim towards a low-carbon society, and use technology to slow the accumulation of atmospheric carbon levels that a scientific consensus tells us is driving catastrophic climate change.

The latter uses carbon absorption to prevent emission of CO2 or methane from an industrial point source such as a coal-fired power plant flue stack, or a cement plant.

The uniqueness of this technology approach

It’s important always to keep the uniqueness of air carbon capture in mind — even as we compare it economically to other approaches that limit or eliminate carbon emissions. This technology directly works on the problem that civilization has right now, which is the carbon in the sky.

If we were in a flooding bathroom, we have the problem of stopping the water from flowing, but then we have the problem of getting all the water off the floor before it does long-term damage to the house. Air carbon capture goes after the carbon that is actually causing climate change, instead of limiting the amount of future carbon that will be emitted.

To the extent that the technology works at scale when deployed, it is a one-stop shopping cure for climate change if sufficient units were built. All of the impacts of climate change — to the extent it is caused by carbon emissions, gone now, gone forever, if we had the will to deploy it.

What does air carbon capture compete against?

“Carbon-capture and storage competes against wind and solar energy,” says Holmes, “by capturing the emissions from fossil fuels that are burned at point sources, such as power plants. In our system, we compete against electric cars, by capturing the emissions from fossil fuels which are combusted in a distributed sources, such as tailpipes.”

How much carbon is emitted at point sources vs distributed sources like tailpipes?

“It’s about 40/60 ratio. 40 percent of carbon is emitted at point sources, and existing CCS technology is always going to be the cheapest way to capture that. The remaining 60 percent is from distributed sources, and it is simply too low in concentration (about 0.004%) for existing CCS technology to be cost-effective.

Why not simply plant trees to capture carbon?

“Air capture is an engineered way of accomplishing what trees and plants do naturally: capture and use CO2,” says Carbon Engineering on their website. “But air capture has some big advantages over such “biomass capture.” Air capture facilities don’t require productive land – the most precious and least renewable environmental resource – plus they can capture much, much more CO2.”

“Air capture does not divert high-value cultivated land away from food production. Capturing CO2 using biomass (trees and plants) depends on the availability of agriculturally productive land, which typically can produce about 500 tons of biomass per square kilometer each year. This biomass then absorbs about 500 tons of CO2 per sq. km annually. Not only can air capture facilities be built on unproductive land, but another benefit is that each facility can capture upwards of 500,000 tons of CO2 per square kilometer per year – 1,000 times more than biomass capture.”

The costs

The first generation of full-scale plants would cost some fraction of $1 billion each (CE won’t say precisely how much for now), capture 1 million tons of carbon per year, and after applying a discounted cash flow over 25 years of straight depreciation you come to a cost somewhere between $150-200 per ton for atmospheric carbon capture, including capex, opex, and the cost of capital. CE declined to give a full cost break-down for this article but noted that they are considering publishing a full cost assessment in the open literature late this year or early next.

The next generation? “Our target is $100 per ton,” says Holmes, “and to reach that figure we need positive outcomes on the engineering we have underway, but it doesn’t require any change in externalities such as the cost of steel dropping in half or something like that. It’s not a case of next year, or the first plant, but that’s the target for the Nth plant and it is based on incremental improvement of our system.”

The Markets

There’s a large merchant market for CO2, especially pure stuff, but there’s nothing like $150-$200 per ton out there in the market. “There are only a few niches at that price, for certain CO2 uses like steel in Japan where they truck in the CO2, but it is very localized, and we’re not going after those,” says Holmes. “The business plan rests on using CO2 for enhanced oil recovery or liquid fuels and chemicals that use CO2, especially for low-carbon markets like California.”

The Bottom Line

It’s a contentious field, carbon capture, and still working its way along the technical readiness curve if we simply note the absence of a full-scale commercial plant. so, does the appearance of a technology that could dramatically change the nature of carbon capture and reduce the cost compared to deploying electric vehicles mean that it is time to stop deploying electrics?

“Some have said there are theoretical limits to this class of technology,” says Holmes. “Others say they are all BS until you have hard data at scale, or that they will be really expensive. Still others say that these technologies are so great that we can take our foot off the gas in terms of developing other technologies. I don’t agree with the former, we think we have a good, workable technology here. But I don;t agree with the latter either. This is not a technology that should be used in place of other ways, but in complement to them.”

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