There's an adage that underlies investments Flint Hills is making to cut pollution emissions at its Pine Bend refinery, which produces most of the transportation fuels consumed in Minnesota.

You no longer smell the huge refinery in Rosemount before you see it.

Since Minnesota regulators fined Pine Bend $6.9 million in 1998 for spills and oil leaks into the nearby Mississippi River, Flint Hills has invested about $2 billion in emission control and efficiency technology, as well as restoring 1,600 acres of the Pine Bend Bluffs nature preserve along the Mississippi River.

The huge facility has lowered emissions of traditional pollutants by about 70% as it increases production of diesel, gasoline, jet fuel, asphalt and other petroleum-based products. In 2021, it also received the U.S. Environmental Protection Agency's Energy Star certification as a top-quartile performer among refineries for energy efficiency.

Still, Pine Bend remains among Minnesota's Big 10 emitters of greenhouse gases (GHG), the driver of climate change that results in increasing numbers of environmental disasters that also are economically devastating nationally.

Minnesota Pollution Control Agency (MPCA) statistics reveal that Pine Bend's greenhouse emissions grew 9% between 2012 and 2020. However, the emissions declined nearly 6% since 2010 on a per million-barrels-of-product basis. Pine Bend production rose 20.6% from 2010 to 2021, or 316,000 barrels per day of product.

Pine Bend in 2019 completed a generator that uses natural gas and biowaste to provide 40% of the electric energy needed to power the refinery. Even though that increased carbon emissions somewhat, the generator pollutes less than the power Pine Bend was taking off the electric grid. It also is constructing a solar plant to raise to 50% its internal power generation.

Another innovative technological play allows Pine Bend to convert sulfur pollution emitted from motor fuel refining into a liquid fertilizer product for area farmers.

"This technology also helps us meet the federal government's requirements for producing lower-sulfur, cleaning burning fuels," said Jake Reint, a Pine Bend vice president. "This new technology also resulted in a slight increase in GHG emissions."

John Linc Stine, former head of MPCA under Gov. Mark Dayton, said: "They were operating as one of the dirtiest of the dirty in the early 2000s. They are now a corporate leader ... and role model for other refineries."

Pine Bend's parent company, Flint Hills Resources, is a Koch Industries subsidiary, long resistant to regulations and pollution controls. However, Pine Bend, which employs 1,000 workers in Rosemount, has become one of the most efficient and cleanest refineries in a dirty business.

"We continue to invest in new technologies that can improve our performance, improve efficiency of our operations and reduce emissions associated with the crude oil we process to produce products people ... will need for a very long time," Reint said.

Bill Droessler, an attorney who formerly administered pollution-disaster Superfund sites, has worked as a program officer with Minneapolis-based Environmental Initiative since 2003.

He credits Pine Bend, also an "EI" member, with investing in pollution-abatement programs on its campus and elsewhere, including Project Green Fleet, the yearslong cleanup of 1,000 old Minnesota school buses that spewed dirty diesel fumes.