Four hours north of New Orleans, in Columbia, Louisiana, a company called Louisiana Green Fuels (LGF) is hoping to build an enormous refinery that would transform trees into jet fuel. The first large-scale factory of its kind, the $2.5 billion project is an example of one of the fastest-growing segments of the biofuels industry: the use of trees and other woody biomass and plant derivatives as the primary fuel component.  

Jet fuel produced this way is marketed as “sustainable aviation fuel.” But a new report from the Environmental Integrity Project on the hazardous air pollution from biofuel production breaks down the problems with assigning such a green label to a highly polluting and poorly regulated process.

The biofuel industry markets itself as an environmentally friendly alternative to petroleum-based fuels. But EIP’s examination of the emissions reports of 226 biofuel plants across the U.S. found that plant-based fuel manufacturers release almost as much hazardous air pollution as oil refineries – and significantly more of some dangerous pollutants, including formaldehyde, a known carcinogen. These findings are included in EIP’s report, Farm to Fumes: Hazardous Air Pollution from Biofuel Production.

The U.S. is the world’s largest producer of biofuels, churning out about 18.5 billion gallons in 2022, or around 40 percent of global production. Historically this growth has been dominated by ethanol production, derived primarily from corn crops. The number of ethanol plants in the U.S. nearly quadrupled in the first decade of this century.  

But the future of the biofuel industry will be more diversified. Of the at least 32 new or expanded biofuels facilities now under construction or proposed, about two-thirds could make fuel from wood or plants to create aviation fuel.

Federal incentives are largely driving this shift. While corn-based ethanol has long been the recipient of beneficial subsidies and eased regulations, the Inflation Reduction Act of 2022 authorized incentives to support the development of “sustainable” aviation fuels and “renewable diesel.” These newer biofuels are sometimes called “drop-in fuels” because they can be dropped directly into conventional engines. This makes them different from ethanol and biodiesel, which must be blended with petroleum products or they will cause problems in conventional engines.  

According to the report, the 27 renewable diesel projects in the works could add 4.7 billion gallons to the nationwide production capacity, more than doubling it compared to 2022. The expansion of sustainable aviation fuel (SAF) is at the center of the Biden Administration’s plans for increasing plant-based fuel capacity in air travel. The administration has a goal of the U.S. producing three billion gallons of SAF annually by 2030 and meeting 100 percent of aviation fuel demand – 35 billion gallons per year – by 2050.

Though emissions data are still limited, permit documents, where available, show that this recent and proposed growth could increase emissions of hazardous air pollutants by up to 139 tons a year, according to EIP’s report. Emissions of volatile organic compounds from the sector could grow by up to 1,421 tons a year and greenhouse gases by millions of tons (with the total not yet clear). These potential emissions estimates are limited to just 27 renewable diesel projects for which permit documents were available. Another 18 projects have been announced, but permit and emissions details have not yet been disclosed.

To further complicate matters, the final tax credit guidance for SAF production under the Inflation Reduction Act, issued by U.S. Department of Treasury in April 2024, heavily favors the ethanol industry. According to the World Resources Institute, allowing SAF tax credits for fuel made from corn ethanol or vegetable oils will actually increase net emissions while diverting valuable cropland away from food production.

“Powering planes with crop-based biofuels is anything but sustainable,” said Dan Lashof, U.S. director of the World Resources Institute. “The United States missed a major opportunity to focus incentives on climate-friendly fuel to help the aviation industry decarbonize.”

Lashof said climate-friendly sustainable aviation fuel could be made from woody biomass from wildfire risk reduction fuel treatments (thinning forests to prevent wildfires), municipal solid waste, or leftover agricultural residues. He said it could also include fuel made from clean hydrogen that captures carbon dioxide.

“Unfortunately, many renewable diesel projects are relying on crops rather than wastes,” said Lashof. “Renewable diesel and sustainable aviation fuel made with genuine waste fats, oils, and greases are beneficial, but the supply is limited and can only hope to provide a small fraction of aviation fuel.”

Lashof said there is also evidence of fraud in which virgin vegetable oils are being intentionally contaminated with small amounts of used oils and labeled as used or waste oil to receive a lower carbon intensity score and more favorable incentives.

The upward trajectory of woody biomass “renewable diesel” mirrors the rapid expansion of another “green” fuel over the last two decades: the wood pellet industry, which pulverizes trees and wood waste into fuel to burn in power plants. The wood pellet industry has a history of underestimating its emissions of hazardous air pollutants and volatile organic compounds and exceeding pollution limits. A 2018 study of the industry’s permitting and emissions records found that 52 percent of wood pellet plants in the U.S. had improperly evaded Clean Air Act pollution control requirements, either by failing to keep emissions below legal limits or failing to install required pollution control systems. The new wood-to-jet fuel industry appears to be on the same track.

For example, according to EIP’s report, the Louisiana Green Fuels facility in Columbia, Louisiana, applied for a permit to operate an 85-megawatt wood-fired boiler, as well as four rotary dryers with a capacity of 665,760 tons per year, to convert one million tons of trees into 32 million gallons per year of renewable diesel and naphtha (which can be used as a fuel). Despite the large scale of this facility, the company applied for an air permit claiming to be a minor source of both hazardous air pollutants and volatile organic compounds (VOCs), pollutants that contribute to smog.

Notably, the company asserted the facility would emit about 91 tons of VOCs per year – just below the threshold of 100 tons that would trigger “major” permit requirements for stronger air pollution controls. The plant also proposed to release up to 24 tons per year of hazardous air pollution.

Remarkably, the company’s emission estimates for VOCs and hazardous pollutants were based on lab tests of a single gram of wood placed in a sealed glass container and heated for just over an hour. The test didn’t even measure the most common wood-product VOC and hazardous pollutant compounds. Nonetheless, the company utilized this “laboratory testing” report to estimate the emissions from the facility’s dryers, which would process 31 tons of wood per hour, or about 28 million times more wood than the single gram supplied for laboratory testing.

In reality, EPA has compiled a vast database of real-world emissions testing on wood dryers that indicate the company’s dryers will more likely emit around 1,000 tons of VOCs and several hundred tons of hazardous air pollutants per year. Despite these obvious maneuvers to evade pollution controls, Louisiana regulators accepted the Louisiana Green Fuels application and permitted the facility as a minor source of air pollution.  

Biofuels plants have a less than stellar compliance history with air pollution control laws. Twenty-one plants were considered “high-priority violators” of the Clean Air Act at the start of 2024, and all of these—19 ethanol plants and two renewable diesel plants—had violations that had not been addressed by local, state, or federal agencies as of April 2024, according to EPA’s Enforcement and Compliance History Online (ECHO) database.  

One ethanol plant, the Grain Processing Corp. facility in Muscatine, Iowa, has failed “stack tests” to determine compliance with pollution limits 16 times over the last five years, without being sanctioned by any enforcement actions or penalties, according to the EPA ECHO database. 

Muscatine County is one of few counties in the Midwest whose air quality violates federal ozone standards, and the only one in Iowa. The county’s unusually high levels of sulfur dioxide may be in part because the county is home to the ethanol refinery. The Muscatine plant reported releasing 83 tons of sulfur dioxide (which can damage the lungs) in 2020, as well as 19,210 lbs. of formaldehyde (a carcinogen); 113,612 lbs. of acetaldehyde (a probable carcinogen); 3,548 lbs. of acrolein (which can cause nausea, vomiting, diarrhea, and lung and eye irritation); and 10,878 lbs. of hexane (which can attack the central nervous system and cause dizziness, nausea, and headaches) in 2022.  

All this suggests that those paying the price for Muscatine County’s ethanol boom are the people downwind in Muscatine County and nearby rural areas.

Lead photo: An ethanol facility in the U.S. Midwest. Photo by iStockphoto.