New Research Reveals the Complex Environmental Impact of Carbon Capture Technologies

Sanjay Purswani

Carbon Capture Technology (CCT) has been heralded as a game-changer in the fight against climate change, primarily for its potential to significantly reduce CO2 emissions from hard-to-abate sectors like power generation. However, the technology's impact on co-emissions is often overlooked, including NOx, SO2, NH3, and particulate matter. Recent research offers a first of its kind lens into co-emissions from power generation plants being retrofitted with carbon capture technology.

Researchers Sanjay Purswani and Dan Shawhan in their paper, "How Clean Is Your Capture? Co-Emissions from Planned US Power Plant Carbon Capture Project," published on Resources For the Future (RFF), offered a meticulous analysis of the co-emissions from power plants being retrofitted with carbon capture technology. The paper uncovers a nuanced reality: while carbon capture can drastically reduce certain emissions like SO2, it may have negligible or even negative effects on others, such as NOx and NH3. These findings pose serious questions about the overall environmental efficacy of carbon capture solutions. "This analysis," Sanjay states, "challenges us to reconsider how we evaluate the sustainability of carbon capture technologies, not just in terms of CO2 but across all emissions."

The detailed analysis conducted by their research presents a critical perspective on the perceived benefits of Carbon Capture Technology. While CCT is championed for its potential to reduce CO2 emissions significantly, Sanjay's findings on co-emissions introduce essential considerations for evaluating CCT's overall environmental efficacy and sustainability. By uncovering the nuanced impacts of CCT retrofits—ranging from substantial reductions in SO2 emissions to potential increases in NOx and NH3 emissions—this research challenges the prevailing narrative of CCT as a universally clean solution. These insights compel us to reevaluate the criteria for CCT's sustainability, emphasizing the need for a holistic approach that accounts for all emissions and their implications on public health and environmental integrity.

The significance of understanding how CO2 capture retrofits influence emission rates cannot be overstated. This study conducts a forward-looking analysis by reviewing engineering studies submitted to the United States Department of Energy, aiming to anticipate the future impact of these retrofits on various emissions. The researchers meticulously evaluated the effects of carbon capture technology (CCT) retrofits, revealing a potential to slash SO2 emissions by up to 99%, while barely impacting PM2.5 emission rates. Conversely, their analysis found that there was a 6% increase in NOx emissions post-retrofit, with studies indicating a stark 75% rise in ammonia co-emissions. These findings, demonstrating significant variances in emission rates for NOx and ammonia post-CCT retrofit, cast doubt on the technology's comprehensive environmental benefits.

Is Carbon Capture a clean and sustainable solution for the hard-to-abate sectors?

While carbon capture is touted as a cost-effective decarbonization strategy for sectors like power generation, its overall sustainability is questioned due to various factors. Current technologies predominantly capture about 90% of CO2 emissions, leaving a remainder that escapes into the atmosphere. The operation of carbon capture equipment demands additional energy, which, if sourced from fossil fuels, could negate life cycle emission reductions, rendering the solution less sustainable. Moreover, the potential rise in co-emissions such as NOx and NH3 necessitates further pollution control measures, potentially increasing public health risks. Sanjay remarks, "Advancing carbon capture is essential for decarbonization, yet sustainability demands we critically assess its full environmental impact, striving for solutions that truly mitigate—not shift—emissions"

Evaluating the Environmental and Health Impacts of Carbon Capture Technology Retrofits
The research conducts a comprehensive analysis on the impact of retrofitting existing coal and natural gas power plants with carbon capture technology on co-emission rates regulated by the EPA in the US. It examines how changes in emission rates could affect human mortality rates, discovering that co-emission changes vary depending on the type of CCT technology used, sometimes even increasing post-retrofit. An intriguing part of the study provides estimates of health damage per MWh for plants with and without CO2 capture projects.

The findings prompt a reevaluation of CCT's environmental benefits, highlighting that while it captures up to 90% of CO2, the potential increase in NOx and NH3 emissions post-retrofit could exacerbate public health risks. This underscores the need for additional pollution control measures in power generation plants, which may increase operational costs or necessitate enhanced control systems.

"In deploying CCS, it's imperative we go beyond environmental impact to meticulously examine its effects on public health. A granular analysis ensures we're not just shifting the burden but truly advancing health and sustainability." Sanjay added.

This nuanced view challenges the perception of CCT as a straightforward solution to pollution, indicating that its deployment must be carefully managed to truly benefit the environment and public health.

How was this useful to the U.S Environmental Protection Agency?

The insights from Sanjay's paper, due to its unique and thorough analysis on carbon capture technology's co-emissions, garnered attention from significant regulatory bodies, including the US EPA, which cited the study in discussions on greenhouse gas control strategies under Clean Air Act Section 111. This citation underscores the impact of Sanjay's work on policy formation, particularly in the realm of carbon capture and low carbon hydrogen pathways for the power generation sector.


Sanjay's research underscores a critical need for policy adjustments in the realm of carbon capture technology (CCT). Given the nuanced findings on co-emissions, it becomes imperative for regulatory bodies to implement stricter controls on these emissions from CCT-equipped plants. This could entail revising emission standards to account for the variability in NOx and NH3 emissions post-retrofit, ensuring that CCT's deployment does not inadvertently harm air quality or public health. Additionally, his insights suggest a broader policy shift towards supporting the development and integration of cleaner energy technologies, emphasizing the importance of evaluating the full environmental impact of CCT projects. To safeguard against unintended consequences, comprehensive environmental impact assessments should be mandated for all CCT projects before approval, highlighting the need for a holistic approach to environmental policy that aligns with the findings on CCT's complex effects.