New carbon capture method uses water and pressure to remove CO₂ from emissions at half current costs

A new, low-cost method for capturing carbon dioxide emissions from power plants and industrial facilities relies on a simple physical phenomenon—the same one that causes bubbles to fizz when popping a bottle of Champagne or cracking open a bottle of seltzer.

The process, called pressure-induced carbon capture (PICC), uses water and pressure to pull carbon dioxide out of exhaust gases before it reaches the atmosphere, offering a cleaner and far less expensive alternative to traditional chemical methods.

Co-inventors Dr. Mark Holtzapple, professor of chemical engineering at Texas A&M University, and Jonathan Feinstein of ExcelThermic Enterprises have filed patents for licensing the technology to power plants, hydrogen facilities, cement kilns, steel blast furnaces and other industrial emitters worldwide. Holtzapple said PICC is a practical solution to an urgent problem because fossil fuel combustion—which releases greenhouse gases into the atmosphere—remains an important component of the global energy mix.

“Our invention is a cost-effective way to address one of the greatest challenges facing humanity,” Holtzapple said. “We can capture carbon dioxide from flue gas using only water and pressure, which makes the process simple, clean and less expensive than competing technologies.”

Traditional carbon capture systems rely on strong chemicals called amines that bind with carbon dioxide to remove it from exhaust gases. Amines struggle to pull more than 90% of the carbon dioxide out of the flue gas, Holtzapple said. Also, the amines are expensive and degrade when exposed to flue gases. Furthermore, permitting 10% of the carbon dioxide to escape into the environment is no longer tenable, he said.

In contrast, PICC uses physical absorption. Because PICC uses no chemical bonds, carbon dioxide pops back out of the water at reduced pressures just as easily as it dissolves in water at high pressure.

“Everybody knows that high-pressure carbon dioxide dissolves in water, and that when you open a bottle of Coca-Cola or beer you see that carbon dioxide bubble back out,” Holtzapple said. Once released, the carbon dioxide can be safely stored or utilized.

How the system works

In operation, flue gas from combusting coal, natural gas or biomass—like forest waste, crop residues or municipal solid waste—is first cooled and compressed. The high-pressure gas is then piped into an absorption column, where cold water flows downward while the gas moves upward through a structured packing that maximizes contact between the two streams. As the nearly clean gas reaches the top of the column, it contacts fresh water entering at the top. There, the last traces of carbon dioxide dissolve into the water, with clean gas releasing into the environment.

The water exiting the bottom of the column contains dissolved carbon dioxide and is transferred to a series of vessels, each operating at lower and lower pressures, where the carbon dioxide progressively bubbles out. Holtzapple said the released carbon dioxide is then ready for compression and injection into underground geological formations, such as saline aquifers, where it is permanently stored.

A lower cost path to near-total capture

Economic analyses show that PICC can capture and compress 99% of carbon dioxide emissions for $26 per metric ton. Other current technologies capture about 90% and cost $50 to $100 per metric ton, Holtzapple said.

Additionally, by adding a small amount of lime—an alkali—to the water, PICC captures 100% of carbon dioxide for an average cost less than $28 per metric ton. At that level of capture, even the carbon dioxide from the combustion air is removed, Holtzapple said.

“Without adding carbon dioxide to the atmosphere, PICC allows us to use abundant fossil fuels on which our civilization is built. Furthermore, by coupling PICC to biomass combustion, we can remove carbon dioxide from the atmosphere cost effectively,” he said.