Carbon Capture And Sequestration — The Dream That Won’t Die – CleanTechnica

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Carbon capture and sequestration represent a shining opportunity for some, like Heirloom, a California startup that opened its first demonstration plant last year. This week, it announced it has raised an additional $150 million from investors, money it will use to expand its operations as it continues to seek a path to profitability. It is also one of several companies involved in the Department of Energy backed regional direct air capture hubs that will theoretically be able to capture one million tons of carbon dioxide a year once operational.

The demonstration plant in California can capture up to 1000 tons of carbon dioxide a year but the next Heirloom facility in Louisiana is expected to remove 17,000 tons of carbon dioxide annually — a statistically insignificant amount compared to the almost 40 billion tons the world pumps into the atmosphere every year. And here’s the thing: A spokesperson for Heirloom told Canary Media recently that the cost of removing a ton of carbon dioxide is between $600 and $1,000 per ton. I am no mathematician, as my readers know all too well, but 40 billion tons multiplied by $600 a ton — the best case scenario at present — is $24 trillion a year.

Heirloom expects the industry to get to a general price of between $200 and $300 per ton by the early part of the next decade, adding that the startup ​“has line of sight to profitability at those prices.” The company ​“is on a trajectory” to hit $100 per ton, the spokesperson said, which is generally viewed by the industry and others as the ideal price point for direct air capture. “We believe DAC is all about cost, cost, and cost — and that it will only scale to make a meaningful difference on climate change if it is affordable,” Heirloom CEO and co-founder Shashank Samala said in a statement.

That is perhaps the most fatuous, self-serving statement we have heard around CleanTechnica headquarters in a long time. Everything is about cost. $200,000 EVs are a non-starter in the marketplace, but $20,000 EVs would find plenty of demand. We know that new technologies take time to scale and prices drop as sales go up, but people have been trying to spin straw into gold in the world of climate capture for quite some time without any tangible success. Mostly, it is a cruel joke that the fossil fuel industry has embraced as a way of saying don’t worry about carbon emissions today, because someday in the far distant future we will figure out how to deal with them. In the meantime, just go back to sleep while we keep on with business as usual. What is especially galling is that they expect someone else to pay to clean up their mess while they laugh all the way to the bank.

The next question is, what do you do with the carbon dioxide when (and if) you capture it? The Heirloom direct air capture process involves shortening the time it takes for limestone to absorb carbon dioxide from years to a few days. The company’s partners then mix the the limestone with concrete or store it underground. That’s easier said than done.

New Study Says Carbon Must Be Stored For 1000 Years

A study by Cyril Brunner, Zeke Hausfather, and Reto Knutti published in the journal Communications Earth & Environment on November 11, 2024, comes to a startling conclusion. In the abstract of the study, the authors write:

“Carbon dioxide removal is essential for achieving net zero emissions, as it is required to neutralize any residual CO2 emissions. The scientifically recognized definition of carbon dioxide removal requires removed atmospheric CO2 to be stored ‘durably.’ However, it remains unclear what is meant by durably, and interpretations have varied from decades to millennia. Using a reduced-complexity climate model, here we examined the effect of carbon dioxide removal with varying CO2 storage durations.

“We found that storage duration substantially affects whether net zero emissions achieve the desired temperature outcomes. With a typical 100-year storage duration, net zero CO2 emissions with 6 GtCO2 per year residual emissions result in an additional warming of 0.8 °C by 2500 compared to permanent storage, thus putting the internationally agreed temperature limits at risk. Our findings suggest that a CO2 storage period of less than 1000 years (emphasis added) is insufficient for neutralizing remaining fossil CO2 emissions under net zero emissions. These results reinforce the principle that credible neutralization claims using carbon dioxide removal in a net zero framework require balancing emissions with removals of similar atmospheric residence time and storage reservoir — e.g., geological or biogenic.”

Anthropocene Magazine puts the results of the study in the vernacular for those of us who are not climate scientists. It says 1,000-year strategies sequester carbon for about as long as it takes for the carbon to be naturally recycled out of the atmosphere. Shorter term strategies that only hold carbon for 100 years will result in the re-release of that carbon long before the emissions that are being offset would leave the atmosphere naturally. The result of these short-term strategies will be excess, unaccounted for emissions and more warming.

For example, suppose there is a need for atmospheric carbon removal to offset 6 gigatons per year of residual carbon dioxide emissions. If that carbon is sequestered for only 100 years, its re-release would result in an additional 1.1°C of warming by the year 2500 compared to permanent carbon storage, the researchers calculated. The findings are “not really” surprising, according to Brunner. “The basis for our conclusions has been well-known for more than a decade,” he says. But the new analysis lays bare the contradictions of the current approach in stark numbers for the first time. “That does not mean that carbon dioxide removal with shorter storage durations than 1,000 years is not useful.” Quite the opposite, he explains. Natural carbon sequestration strategies can improve air and water quality and safeguard biodiversity, and might also be useful to offset emissions of shorter lived greenhouse gases such as methane. More research is needed, he says.

The time scale of carbon sequestration matters a lot, Brunner and his colleagues suggest. Using a simplified climate model to find out how different durations of carbon storage would affect total warming, they found that only 1,000-year carbon storage strategies will avoid further warming from residual carbon emissions. Broadly speaking, there are two ways to sequester carbon removed from the atmosphere. Natural carbon sequestration, in which plants absorb carbon dioxide from the air and store it in their tissues, lasts about 100 years. Forced carbon sequestration, in which carbon dioxide is injected into underground rock formations or sunk in blocks to the bottom of the ocean, should last for at least 1,000 years.

The Takeaway

Sharp-eyed readers will notice the typical news story about carbon sequestration seldom mentions how long the carbon will be sequestered — a material flaw in any conversation about direct air capture. The assumption is that once sequestered, it will stay sequestered, but we all know about the word “assume” by now, don’t we? That suggests all the fancy promises we hear about sucking carbon dioxide out of the atmosphere and piping it underground are apt to be much too optimistic at best and deliberately misleading at worst.

The researchers are attempting to close a loophole here, but will anyone listen? Certainly, based on past experience, there is little reason to think the fossil fuel crowd wants to delve too deeply into the ramifications of this research. They have been lying to us for 7 decades and are not about to let little things like truth or accuracy interfere with their carbon capture dream.