Scientists Identify Houston Power Plant as Dominant Source of Cloud-Forming Aerosols

Story by:

• Robert Monroe - [email protected]

Share This:

• Share this story on Linkedin
• Share this story on Facebook
• Share this story on Threads
• Share this story on Twitter
• Share this story via email

Article Content

Research by atmospheric scientists at UC San Diego's Scripps Institution of Oceanography and colleagues pinpointed an individual coal-fired power plant in Houston, Texas, as the main source of particles most likely to encourage formation of clouds around the metropolitan area.

A large portion of aerosols from W.A. Parish Generating Station serve as what are called cloud-condensation nuclei (CCNs). Scripps Oceanography atmospheric scientist Greg Roberts and colleagues found that the plume extended over downtown Houston and more than 110 kilometers (65 miles) downwind. To map it, the team took measurements from aircraft with state-of-the-art instruments, a setup Roberts said gave researchers a unique opportunity to pinpoint emissions sources.

Even though public health impacts of the emissions from the coal-fired power plant was not a goal of the study, Roberts observed that such particles cross the entire Houston metropolitan region and are of the size most commonly associated with respiratory illnesses. The breakthrough of the research identified a clear source, the W.A. Parish Generating Station southwest of the city, in a region that includes urban traffic, industrial refineries and a major port.

"Cloud-forming particles are also the size of particles that go deepest into the lungs," said Roberts. "There's always been a layer of doubt as to where those particles are coming from."

Two related studies have been published previously, but the latest revealing the pollution source appeared June 28 in the Journal of Geophysical Research with Roberts as lead author. The National Science Foundation and federal Department of Energy funded the research behind all three studies.

Houston is a popular location for atmospheric scientists to study pollution and clouds, said Roberts. The urban area is a heat island that emits a range of human-sourced particles from vehicles, oil refineries, cargo ships and power plants - all of which impact the formation of clouds and intensity of the summer storms and stand in stark contrast to the relatively clean rural regions surrounding Houston. Studies like Roberts' serve to help scientists understand the dynamics of cloud formation and deep convection in summer storms, which has been among the most difficult variables for numerical weather prediction models to simulate.

For some residents of greater Houston, the findings may provide additional evidence that W.A. Parish is as harmful to health as they suspect. Their contention has been the subject of media coverage in recent months.

Roberts and colleagues published one study in May from the ESCAPE (Experiment of Sea Breeze Convection, Aerosols, Precipitation, and Environment) campaign in the journal Science Advances that simplifies how scientists describe mixing at the edge of clouds. Another paper, released two weeks ago, studied strong updrafts and their role in intensifying storm clouds in polluted environments.

This newest study singles out the W.A. Parish Generating Station as exerting a disproportionate impact on clouds and regional air quality compared to the other sources of particles in the Houston metropolitan region.

The scientists outfitted a Convair CV-580 research aircraft provided by the National Research Council of Canada with instruments to measure aerosols and clouds. Two instruments, built at Scripps' Marine Science Development Center, specifically measured the concentration of cloud-active particles or CCNs. The aircraft performed 24 research flights in May and June 2022. Measurements from the flights were combined with data gathered by ground-based mobile aerosol facilities and radar stations around Houston operated by the U.S. Department of Energy.

Besides Roberts, the ESCAPE team included researchers from Stony Brook University in New York, Brookhaven National Laboratory in New York, the Cooperative Institute for Severe and High Impact Weather and Research Operations (CIWRO) in Oklahoma, the University of Oklahoma, Texas Tech University, Colorado State University, Penn State University, the Stratton Park Engineering Company in Colorado, Texas A&M University, Michigan Technological University, the National Research Council of Canada, the National Center for Atmospheric Research in Colorado, Los Alamos National Laboratory in New Mexico, the NOAA/OAR National Severe Storms Laboratory in Oklahoma, and McGill University in Montreal, Canada.