An update from an organization conducting an ongoing study of the air quality in the Fairbanks North Star Borough nonattainment area may indicate that emission sources from power plants contribute less sulfur dioxide than previously thought.
Bill Simpson, a University of Alaska Fairbanks Geophysical Institute researcher, presented the latest details from the Alaskan Layered Pollution and Chemical Analysis team to the borough’s Air Pollution Control Commission Wednesday night.
ALPACA involves more than 100 researchers and scientists from 20 organizations who have been studying the air quality in Fairbanks and North Pole. More than 40 people were in Fairbanks in February 2022 to conduct surveys and monitoring.
Sulfur dioxide is a sulfate and part of what makes up the fine particulate matter (PM2.5) pollution in the nonattainment area.
He said two types exist, including primary sulfate and secondary sources of sulfate. Primary sulfate is caused by direct combustion, while secondary sulfates sources are a byproduct of combustion-caused SO2 gases.
“The real reason you want to know primary and secondary sulfate is that the primary is usually more controllable and linearly reduces with less fuel use,” Simpson said.
The Environmental Protection Agency is considering mandates to the State of Alaska to better monitor and regulate the sources, including stronger emission controls on the four power plants in Fairbanks and North Pole. The recommended actions are part of a proposed partial disapproval of Alaska’s Fairbanks PM2.5 Serious State Implementation Plan (or Serious SIP).
The air pollution commission approved a motion to forward Simpson’s data to the borough mayor and Assembly as a way to convince the EPA that some of its anticipated sanctions will aren’t necessary.
“The EPA is looking right now at disapproving parts of the Serious SIP and that starts a sanctions clock,” said Michael Pollen, the commission chair.
Another change could require Alaska to mandate a switch from Heating Oil No. 1 to Ultra Low Sulfur Diesel, which generates much less S02. The proposed change has sparked opposition from the state, the borough and local business organizations, citing a significant price increase.
Simpson noted ALPACA and Department of Environmental Conservation data that space heating, such as wood stoves and oil boilers, only make up a combined 21.5% of total sulfur dioxide emissions in the nonattainment area.
About 35.9% comes from airport traffic and 42.5% from point sources such as power plants, neither of which make it to ground level.
“It really argues that point sources are not equal contributors to ground level pollution,” Simpson said.
Sulfur dioxide, or S02, tends to be lighter because it mixes with water in the air. January and February have the worse periods of So2 in Fairbanks, Simpson noted, based on the recent survey results.
Researchers are working on a research paper based on a one-dimensional modeling that determines the main source of ground based S02, compared to sources that comes from power plant stacks.
“Essentially what is emitted at the ground level stays at the ground level, while most of what is emitted aloft is not making it to the ground,” Simpson said.
Researchers conducted experiments that included shining a light from downtown Fairbanks to Birch Hill using mirrors between Jan. 29 and Feb. 3, 2022, during a strong inversion period.
“We determined how gas was between you and the mirrors,” Simpson said. At Nordale Education Center, surface-emitted pollution was trapped below 12 meters.
Moving higher in elevation, at around 73 meters above the valley floor, were much less and not trapped. The ALPACA team used data and equipment from Alaska Department of Environmental Conservation in a 2.5 square mile area centered on downtown.
Pollution is normally dispersed as it moves up through the layers until winds disperse it. An inversion traps it at the urban layer due to a lack of wind.
“The model has no power plant plumes in it at all,” Simpson said. “It only uses ground-based results.”
However, he added, another analysis would be needed to track how sources from a downtown power plant plume as it travels. Some ALPACA team members and DEC are conducting separate models on such sources, but he said those studies take time to complete.
SO4, a sulfate caused by PM2.5, came down slightly after the DEC fuel switch mandate, but not as much as the S02 levels. He added another year may show more significant decrease.
“There is definitely a lot of work to understand [SO4] changes,” Simpson said.
Hurst Road in North Pole, which has about twice the national standard of PM2.5 levels, only contains small amount of sulfate.
Simpson said ALPACA has also monitored the overall decrease in recent years of both PM2.5 and SO2 wintertime emissions since 2014. PM2.5 emissions have gradually decreased over the nine years by half, with flat period between 2018 and 2020.
Based on DEC data, Simspon said sulfur dioxide levels, on the other hand saw a greater trend downward, with the exception of a spike in 2020, followed by another sharp spike by 2022.
Simpson noted the S02 decrease happened before Alaska mandated a switch from Heating Oil No. 2 to Heating Oil No. 1 in September 2022. He noted there was a 57% decrease between the 2014-15 winter season and 2022-23 season.
Just after the switch, he noted there was a 33% drop in SO2 levels based on a three-year average.
“It’s definitely been a big reduction in S02 in Fairbanks due to this legal change and due to changes before that,” he said.
However, he noted a single strategy such as a to shift toward ultra low sulfur diesel to address sulfur levels “is not going to get every part of this airshed cleaned it up.”
“It’s probably done good things for people in Fairbanks at not a huge cost of going to No. 1 heating, but the situation in North Pole is not going to be solved simply by a change in fuel sulfur,” Simpson said.
Simpson noted overall policy and economic decisions lie with EPA and Alaska DEC, adding that the borough has already done a lot to clean up the air.
“People are burning dryer wood, have changed out stoves and not burned wood on days when dispersion was bad,” Simpson said. “You’ve got to keep up a multi-faceted strategy.”
Pollen, the commission chair, called the data revealing and crucial to countering the EPA’s proposed sanctions, which include tighter S02 emission controls on power plants and a switch to more expense Ultra Low Sulfur Diesel.
“Everybody knows [ULSD] is much more expensive and we don’t make that here in Fairbanks, so we have to import it with vehicles that emit [pollution],” Pollen said. “We basically damage the economy by not allowing a local resource manufacturer to produce No. 1 heating oil.”
He added such policies an economic consequence that “could burden taxpayers, homeowners, government and manufacturers.”
Simpson said better clarity could be found by looking at the economics based on what people might do if heating oil prices increase.
“You would need to do a more encompassing view of if heating oil went up, whether people would switch to wood,” Simpson said. He added that people could as easily transition to natural gas as the Interior Gas Utility expands its distribution system.