To get rid of carbon dioxide from our atmosphere, one sure way to go would be capturing the gas directly from the air. However, this is more of a challenge than would be capturing the carbon at the source of its emission, the power plant furnaces, say Stanford and MIT researchers.
A similar study has already been performed by Princeton researchers this spring, when they were saying that a machine that would be able to scrub carbon dioxide of a 1000-MW plant would have to stretch over 30 kilometers.
Now, Jennifer Wilcox and her colleagues at Stanford and MIT, has published a study in the Proceedings of the National Academy of Sciences, according to which it would be much more economically efficient to capture carbon at power plants, cement plants and refineries.
“The concentration of CO2 in outside air is 300 times less than in the coal-fired flue gases emitted from a power plant. The lower atmospheric concentration makes removal from air much more expensive than removing CO2 directly from the flue gases at the source,” she said.
Comparing the alternatives, Wilcox reached the conclusion that it would cost some $1,000 per ton to sequester carbon after it had been emitted and some $50 to $100 per ton to catch it before exiting the furnace.
“Direct air capture sounds great in theory,” Wilcox said. “In reality, though, a lot of energy is required, and using fossil-based energy sources to capture and regenerate the carbon dioxide could readily result in more carbon dioxide entering the atmosphere than is captured.
Furthermore, if we were to follow the first, expensive option, the energy used would not be allowed to come from other coal-powered plants, but from renewables like solar and wind. On the other hand, it would make more sense replacing coal plants altogether than using clean energy to sequester what’s already in the air.