Beyond the Smokestack

The document evaluates three industry-proposed methods for reducing carbon emissions from gas plants: hydrogen cofiring, carbon capture and storage (CCS), and biomethane. It concludes that these approaches often fail to achieve targeted emissions reductions when full life cycle impacts—such as upstream methane leakage, energy penalties, and production emissions—are considered. Furthermore, the brief argues that these technologies perpetuate environmental and social inequities by maintaining the operation of gas plants. In contrast, the report finds that transitioning to renewable energy sources like wind and solar provides superior reductions in carbon, air, and water pollution while offering lower costs and fewer land-use impacts.

• Hydrogen cofiring can lead to an overall increase in climate pollution compared to burning gas alone, depending on the production method. For example, producing 'gray' hydrogen via steam methane reforming yields approximately 12 kg CO2e/kg H2, which emits twice as much CO2e as the cofiring reduces at the smokestack.
• Hydrogen cofiring may increase public health risks by raising nitrogen oxide (NOx) emissions. Without changes to pollution controls, a 97 percent hydrogen blend—required to achieve a 90 percent smokestack CO2 reduction—could result in NOx emissions twice as high as a gas plant without hydrogen.
• Carbon Capture and Storage (CCS) at gas plants is undermined by an 'energy penalty' and upstream methane leakage. A 15 percent energy penalty means a plant must increase generation by 18 percent to maintain the same net electricity output, which increases gas consumption and associated methane leakage, potentially resulting in overall emissions 4–5 times the target.
• The climate benefits of biomethane are often based on flawed 'avoided emissions' assumptions. These calculations assume biomethane would have otherwise been vented to the atmosphere, allowing plants to claim a 90 percent reduction in emissions even if they still use fossil gas, whereas comparing biomethane to flaring or climate-smart farming significantly reduces its purported benefits.
• Renewable energy sources provide significantly lower life cycle carbon emissions than gas plants, with solar and wind generation responsible for 91 and 97 percent fewer life cycle carbon emissions per unit of electricity, respectively.
• Gas plants disproportionately impact marginalized communities; while people of color and low-income individuals make up 40 percent and 30 percent of the US population, they constitute 54 percent and 34 percent of people living within three miles of a gas plant.

APA

Union of Concerned Scientists (2024). Beyond the Smokestack. https://www.ucs.org/sites/default/files/2024-10/Beyond_the_Smokestack_issue-brief.pdf

Chicago

Union of Concerned Scientists. Beyond the Smokestack. 2024. https://www.ucs.org/sites/default/files/2024-10/Beyond_the_Smokestack_issue-brief.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=Beyond the Smokestack |date=October 2024 |url=https://www.ucs.org/sites/default/files/2024-10/Beyond_the_Smokestack_issue-brief.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2024beyond, author = {{Union of Concerned Scientists}}, title = {{Beyond the Smokestack}}, institution = {Union of Concerned Scientists}, year = {2024}, month = oct, url = {https://www.ucs.org/sites/default/files/2024-10/Beyond_the_Smokestack_issue-brief.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }