Is Carbon Capture Technology a Viable Solution?

Carbon capture utilization and storage (CCUS) is widely viewed as a necessary technology to facilitate the continued use of fossil fuels in light of climate change concerns around the world. One company that has been highly focused on CCUS research and development, as well as deployment of the technology, is Mitsubishi Heavy Industries (MHI).

Tiffany Wu, business development manager for MHI America, was a guest on The POWER Podcast, and talked about the technology and its future prospects. Wu has a degree in chemical engineering and began her career working intimately on CCUS projects, including at Alabama Power’s Plant Barry facility and on the Petra Nova project—POWER’s Plant of the Year in 2017.

“I think that carbon capture is going to become an increasingly important part of the energy portfolio,” Wu said. “In the absence of any regulatory pressure in the U.S., what matters to the industry is whether or not these carbon capture facilities are going to be economic or not. So, our customers are trying to come up with not only environmentally friendly projects, but also economic projects.”

Wu said there are reasons for optimism. “In the U.S., we have a really great environment for [viable projects], because one, we have all of this history with enhanced oil recovery [EOR]. And so, there’s a lot of infrastructure in place that they can build off of. And then the other thing is that there have been a lot of federal incentives such as the 45Q tax credit that can help bolster the technology and these projects.”

Section 45Q provides a tax credit on a per-ton basis for CO2 that is sequestered. Beginning in 2008, an incentive of $20 per metric ton for CO2 geologic storage and $10 per metric ton for CO2 used for EOR or enhanced natural gas recovery was available. In February 2018, the credit increased to $35 per metric ton for EOR and $50 per metric ton for geologic storage by 2026. The $35 tax credit is also available for non-EOR CO2 utilization and direct air capture projects.

MHI’s carbon capture process is known as Kansai Mitsubishi Carbon Dioxide Recovery (KM CDR). It has been installed on at least 13 commercial plants around the world. Wu explained how the KM CDR process works.

“It’s very similar to other amine-based processes,” she said. “Flue gas is introduced into the system, and in one of the initial towers, which we call the absorber, we also introduce a solvent. known as an amine, and the CO2 attaches itself to the amine. So, through that process, we’re able to capture 90%—and in some cases, we can capture up to 95%—of the CO2 from the flue gas.”

The process is a closed loop system, and the amine is reused. Wu continued, “We introduce the amine that’s rich in CO2 into another tower we call a regeneration tower, and in that tower, steam is introduced and the amine is heated up so that the CO2 separates itself from the amine.”

The CO2 is compressed and the amine is sent back to the front of the process. This sort of technology is used by various industrial sectors, including for acid gas treatment. In each case, there may be different flue gas constituents, but the process is essentially the same.