Carbon Capture Can't Save Us
by Joe Armstrong | published Apr. 5th, 2022
Carbon is the basis of life on earth and, potentially, the bane of it. It has been a common consensus in the scientific community that elevated carbon in our atmosphere due to human activity has led to an overall warmer climate.
This has only become more apparent in recent years, as increasingly tangible consequences have caught up with the science. From Sir David Attenborough to your local meteorologist comes a ubiquitous refrain — the world is in trouble. And to this leaders have responded with pledges. But is it enough?
Notwithstanding that metaphorical lines in the sand are still at the mercy of changing tides, a lot of the damage has already been done. Even if humanity went carbon-neutral today, temperatures would continue to rise, a product of our already-oversaturated atmosphere.
Enter Carbon Capture and Sequestration (CCS). Essentially, fans suck in high volumes of air, using a reusable media — a sponge-like foam — to absorb carbon dioxide. This media is treated to high temperatures, which re-releases the gas into a controlled environment; specialized vessels from which it can't escape back into the atmosphere. The next step is figuring out what to do with it.
Professor Eric Williams, of the Golisano Institute for Sustainability at RIT, has researched the CCS technology being used at coal plants.
“Carbon dioxide just isn’t that valuable," Williams said. " ... The money that you’re going to spend to turn the carbon dioxide gas into something solid is going to cost more than what you’re going to get from being able to sell whatever that is."
It’s a little disillusioning that such a matter can be boiled down to simple economics, but the problem is also one of thermodynamics; more specifically, the conservation of energy.
There are two primary forms of carbon capture, the first of which is the aforementioned CCS attached to fossil plants. These are very effective, capturing around 80-90 percent of emissions. The issue with this method is that by definition it is a net-positive carbon footprint, only mitigating emissions from an otherwise preeminently harmful industry.
What’s worse, the CCS process itself comes at the price of efficiency, since it draws energy from the system at a penalty of up to 20 percent. This means that to achieve the same energy output, modified plants need to burn more fossil fuels, an expense that comes out of consumers' wallets further down the line.
The second method is called Direct Air Capture (DAC). It’s exactly what it sounds like — an enormous array of fans draw air from the atmosphere at large. A net negative, but still far from ideal.
DAC is less effective than its counterpart, the carbon-dioxide content in average air being less dense at roughly 400 parts-per-million, meaning that for every million liters of air that are processed only 400 are carbon. It’s essentially an effort to cram the genie back in the bottle and takes an astronomical amount of volume, time and energy. The largest existing DAC plant in the world based out of Iceland, Orca, will set our annual emissions back by a meager three seconds.
Meanwhile, the core dilemma persists. CCS is by nature unsustainable on its own — either a net energy drain or a net carbon gain. Bad for business, or bad for the environment.
“In some form or another,” Williams said, “money has to move from the government — from the people — to these things, that is separate from the economies, from the costs and revenues of the process.”
Others seek economical means of sequestration. Marc Porosoff is an assistant professor at the University of Rochester with a background in chemical engineering. Porosoff has published research on hydrogenation, a process by which carbon dioxide can be used to synthesize polymers.
“There’s no replacement for things like polypropylene and polyethylene," Porosoff said, "so rather than derive it from crude oil ... we can replace that with CO2 from the air ... that gives you a means of creating something that we need as humanity, and a method of potentially sequestering carbon dioxide."
But this kind of sequestration, just like the capture itself, will need to be scaled up massively before any kind of benefit can be seen, environmentally or economically.
“Theoretically,” Porosoff said, “it is possible to make it economically viable — especially when you start to think about scaling it up — but right now we’re not quite there yet.”
The real problem with carbon dioxide isn’t just how to get it out of the air; it’s how much is already up there.
“The magnitude of the problem is unlike anything humanity has ever dealt with before,” claimed Porosoff. “We’re talking on the order of ten gigatons ... the only things that we make on that magnitude are things like steel, concrete and petroleum.”
"The magnitude of the problem is unlike anything humanity has ever dealt with before."
Porosoff’s work with polymers makes its niche in the petroleum industry — other researchers have found ways to use calcium carbonate in concrete, which also happens to be one of the world’s biggest emitters. Bit by bit, carbon can be stowed away in the nooks and crannies of our everyday lives, or even the very ground beneath our feet.
The Other Shoe
But out of sight is not out of mind anymore, and that mentality is outdated.
“Anyone who tells you that this is going to occur perfectly fine without any consequences is not giving you an honest answer,” said Porosoff.
There's no telling what may happen if we pump billions of tons of carbon beneath the earth’s crust — the very chemical formation of carbonate releases heat of its own, which at that scale could be its own source of global warming.
Of course, there is, and always has been, a sober alternative to this kind of technology.
“The cheapest way that people usually think about [CCS] is growing more forests," Williams said. "You’ve just got to make sure that nobody burns them down.”
There's the caveat. Our carbon footprint has left an unfathomable crater in the world, one in which it is hard to gain a foothold. What sets carbon capture apart from other budding technologies is that failure is not an option. And the sooner everyone gets on board, the better.
"You almost need to think about carbon capture as similar to insurance, where everybody pays and everybody benefits," Porosoff said.
"You almost need to think about carbon capture as similar to insurance, where everybody pays and everybody benefits."
This will take cooperation on a legislative, industrial and social scale. In the meantime, to get into the spirit of things, consider planting a tree.