Anaerobic biodigester equipment.
Anaerobic biodigester equipment. Credit: Maas Energy Works, Inc.

Bob Baenziger, Jr. had made many dives in dangerous conditions over the course of his career. He was trained in the U.S. Army and had long worked diving on offshore oil rigs.

But in June 2021, Baenziger lost his life on a diving job much closer to his Illinois home — in a sweltering, asphyxiating stew of manure on an Iowa family cattle farm. He was trying to fix a broken cable submerged in an anaerobic biodigester, a type of tank that turns animal waste into biogas and is widely billed as a renewable solution to America’s dependence on fossil fuel energy.

Neither state nor federal regulators investigated his death, since as an independent contractor working at a farm with fewer than 10 employees, no workplace oversight programs applied.

The U.S. Occupational Safety and Health Administration (OSHA) is “forbidden from using federal dollars to inspect any farm with 10 or fewer employees, even if it is a death, even if it is 10 deaths,” said Deborah Berkowitz, a former chief of staff and senior policy adviser for OSHA, and now a practitioner fellow at the Kalmanovitz Initiative for Labor and the Working Poor at Georgetown University.

As federal and state incentives and mandates make it increasingly attractive for hog and dairy operations to make biogas out of their methane-intensive waste, community groups and environmental organizations have argued stridently that biogas collection is a false solution to the climate crisis, one that actually causes rather than mitigates greenhouse gas emissions while increasing the pollution burden on neighbors, who are disproportionately likely to be people of color.

Baenziger’s fate, meanwhile, highlights a little-examined piece of the puzzle: working with and near manure is inherently dangerous, and biogas expansion could mean more risks for workers who already have few protections. That includes risks to animal agriculture workers, who are largely unprotected by federal labor laws as they toil in barns that are ever-more-densely packed with animals.

In these concentrated animal feeding operations (CAFOs), hog and cow manure is typically stored in lagoons that release deadly hydrogen sulfide, which can instantly overcome workers, causing them to asphyxiate and die. And when workers fall in lagoons, they are likely to suffocate or lose consciousness before they can get out.

More than a billion tons of manure are produced every year in the U.S., according to the USDA, and many critics think biogas incentives will encourage companies to expand their operations, producing even more. Biogas incentives are most lucrative for larger operations that raise animals in CAFOs, creating large volumes of manure. Those operations may be spurred to pack in more animals to increase not only farming profits, but profits from biogas, adding to concerns for worker advocates.

On the most basic level, biogas production entails stockpiling manure in covered spaces to collect the gas coming off it, then burning that gas to generate electricity or heat, refining it further so it can be injected into utility natural gas pipelines, or using it as transportation fuel. Biogas proponents say this process makes animal agriculture cleaner and safer than it otherwise is, since hazardous manure pits located outside of CAFOs are covered rather than left open and gas is captured rather than released into the atmosphere.

Daryl Maas, president of Maas Energy Works, which owns or manages about 60 biogas operations in states including California, Texas, Idaho, and Arizona, is among those that assert that biogas is safer. Maas Energy partners with existing dairies or hog farms and collects the biogas from their manure, often by building new covered manure lagoons and biodigesters on-site, and sending the gas to refining hubs to prepare it for pipeline injection.

Maas said that since such new infrastructure must meet the most updated state health and safety standards, it is often less polluting and safer for workers than the farm’s pre-existing infrastructure, which typically involves uncovered, outdoor manure pits. He said that since gas is collected and transported to hubs at low pressure, there is little risk of explosion at farms.

“We plug ourselves into the end of a process,” collecting that manure, Maas said. “We say rather than running it into a storage pond, why don’t you let it flow into a digester? It’s hard for dairy farmers to maintain a digester and be an expert at taking care of cows and everything else. Our job is to run the digesters.”

Not all farms are run by outside companies, and critics of the biogas sector—including farmers, professors, and advocates for workers and the environment—say little is known about how people working on farms will be affected by the burgeoning biogas sector, and more attention is needed.

“This is a new, unproven technology,” said Robert Martin, program director of food system policy at the Johns Hopkins Center for a Livable Future, who co-authored a 2021 report on public health threats facing farmworkers. “It’s proven it can capture methane, but  . . . I don’t think anyone has looked at the risk to workers.”


“It’s proven it can capture methane, but  . . . I don’t think anyone has looked at the risk to workers.”


Among issues unconsidered is how workers may fare inside of CAFOs when farms bring in more hogs and cows for biogas production. That trend could expose workers to more waste inside barns and decrease the indoor air quality already known to cause long-term illness in CAFO workers.

“Many of these people are living in the shadows, they’re among the most powerless workers in America,” said Austin Frerick, a seventh-generation Iowan and deputy director of the Thurman Arnold Project at Yale University, focused on anti-trust and sustainability in agriculture. Many experts say the risks to workers involved in manure collection should discourage the government from promoting it.

That concern has reached Congress. In letters to the USDA in August, five senators asked for more information from the agency as to whether incentivizing biogas would reduce emissions from animal agricultural overall and whether it had explored their impacts to public health.

And while Maas and other proponents say biodigesters are safe and people should not need to enter the covered spaces, some stories suggest otherwise—including the story of Baenzinger’s death, and a May spill at a biodigester on a family hog farm in North Carolina. There, the covering on a manure lagoon ruptured and for weeks a noxious foam spilled out onto the surrounding land. The lagoon had contained not only manure but up to 210,000 pounds of decomposing dead hogs that the farm was permitted to use as biogas feedstock. (Officials at the farm did not respond to a request for comment.)

“You’re not solving the actual problem,” said Frerick. “It’s clear that people shouldn’t be scuba diving in shit and drowning to death for a climate change solution.”  

An anaerobic digester in Milford, Utah.
An anaerobic digester in Milford, Utah. Credit: Align RNG

Incentives and expansion

The EPA’s AgSTAR database shows that there are 331 biodigesters on hog, dairy, and poultry farms as of 2021, with 91 in California followed by 39 in Wisconsin.

Biogas can be burned on-site to generate electricity, and biodigesters have been a boon to some small farms, giving them a way to dispose of manure while also producing their own heat and electricity, saving money on utility costs. Manure is otherwise spread on fields as fertilizer, though farms often generate more than the soil can absorb. Biodigesters reduce the burden, though the digestate left over from a biodigester is still spread on fields later.

Biogas from manure may be purified so that it is chemically identical to fossil fuel natural gas, which can be injected into interstate natural gas pipelines to be sold to utilities—either for distribution to customers for heating and cooking or to use in natural gas-fired power plants to make electricity. But such refining is expensive and regulations often make it hard to inject gas into pipelines, so smaller farms sometimes struggle to profit from this option. 

In 2009, at the United Nations’ COP 15 in Copenhagen, Tom Vilsack—Agriculture Secretary both then and now—announced a memorandum of understanding (MOU) between the U.S. dairy industry and the U.S. Department of Agriculture (USDA) to incentivize biodigesters. 

“This MOU will most likely allow the largest operations to siphon off even more scarce taxpayer dollars,” wrote John Peck, executive director of Family Farm Defenders, who was in Copenhagen for the announcement. “Once again, sustainable grazing operations—which don’t have a manure problem worth digesting and happen to account for a third of all dairy farms in a state like Wisconsin—will gain nothing for their environmental stewardship.”

Despite that preliminary support for biodigesters, the expense of installing one and the difficulty of getting the gas to larger markets at that time meant that, until very recently, biodigesters remained concentrated mainly on smaller farms. But with new federal and state incentives and changed utility policies, in the past few years Peck’s words have proven prophetic.  

The increasing opportunity to inject gas into interstate pipelines and sell gas on open markets, paired with increasing incentives and subsidies for biogas production, has led larger corporations to enter the arena.

State and regional programs like California’s Low Carbon Fuel Standard typically allow participation from operations nationwide, making it possible for hog farms in the Southeast to collect renewable transportation fuel credits sold in California. Phoebe Seaton of the Leadership Counsel called such emerging markets “a manure gold rush,” a phrase echoed by other groups.

Most states with renewable energy targets now include biogas as eligible for meeting their renewable energy targets, and farms can often sell biogas to energy companies or sell offsets in private markets. Some utilities and regulators have also changed their policies to make it easier to inject refined biogas into pipelines, adding opportunity. And federal incentives are also taking hold.

The Inflation Reduction Act passed in August expands the number of programs that can fund biogas through the Department of Agriculture. It also made biodigesters eligible for the Investment Tax Credit if construction begins by 2025. This tax credit had proven crucial to making solar energy financially viable, and biogas proponents hope the tax credit will similarly help electricity generated with biogas reach cost parity with other energy sources.

Maas said incentives have indeed made biodigesters profitable, attracting larger companies while also providing support to some small farms.

He said that in the early 2000s, available incentives “would offset the cost of a digester, but there was no revenue model—once you built it, you had no way to make money from it. You’d have a lot of ribbon-cutting ceremonies and newspaper articles saying, ‘Isn’t it great we’re building this digester?,’ but the cost of operating it was more than the energy [revenue] generated. Now we have a higher-revenue model where you can operate a digester profitably.”

Larger corporations are now generating biogas at their own large farms or partnering with existing farms, as Maas Energy, California BioEnergy, and other companies do.  

(California Bioenergy did not respond to multiple requests for comment; nor did Montauk Renewables, which is planning a similar operation in North Carolina, producing biogas out of the manure from nearby hog farms).

Giant hog producer Smithfield Foods is partnering with Dominion Energy on a $500 million joint venture known as Align RNG to produce biogas in several states. In 2020, Align launched a Utah project that collects biogas from 26 farms with biodigesters, refining the biogas and then putting it into existing distribution pipelines. When the Utah project is fully operational next year, it will produce enough gas to heat 3,000 homes, Smithfield spokesman Jim Monroe said. In North Carolina, a project is in the works to collect biogas from 19 farms, transported to a biogas refinery through a 30-mile pipeline. Monroe said the North Carolina project will be operational in 2023.

A central conditioning facility in Milford, Utah.
A central conditioning facility in Milford, Utah. Credit: Align RNG

Smithfield has said the company will eventually funnel almost all its manure into biogas production in multiple states.

Smithfield, like other companies, bills the move as a win for climate and greenhouse gas reduction. But in addition to the environmental problems critics have emphasized, workers may face risks as incentives spur consolidation and CAFO expansion.

Longstanding concerns, little action on manure danger

Following fatal accidents, the National Institute for Occupational Safety and Health (NIOSH) issued an alert about the dangers of manure pits in 1990, though it noted the OSHA would not be able to enforce its safety recommendations on farms with fewer than 10 employees. In 1993, NIOSH issued another such alert, citing the 1992 deaths of a father and son and an uncle and nephew in separate family farm accidents involving manure pits. While those alerts struck an urgent tone, there are still no binding safety standards for manure pits, and fatalities have continued.

Media reports compiled by Civil Eats show the horrific ways workers—often immigrants—have perished in and around open pits over the past two decades. In multiple cases, several family members working together perished, including two separate father-son duos who died in July 2015 in manure pit accidents in the Midwest. Last summer, in Ohio, three brothers were asphyxiated by gasses associated with manure on their family farm as they were repairing a pump in a pit.

Last spring at a Colorado dairy, Juan Panzo Temoxtle died when a manure vacuum truck he was driving accelerated into the pit and he was unable to get out. His family lamented how he’d been working to save money to build a home for his family in Mexico, local media reported, and a farmworkers’ rights initiative was formed in his name.  

In Temoxtle’s case, OSHA investigated and levied a $20,000 fine. But because OSHA is prohibited from investigating deaths on farms with 10 or fewer employees, it often can’t levy fines or make safety recommendations in such instances. 

The federal government has meanwhile continued to make safety recommendations for manure handling, including as part of dairy industry Local Enforcement Programs like one focused on New York state in recent years. But worker advocates say those safety recommendations are often ignored by farms. And there has been little government attention to biodigester worker safety specifically.  

An article by a Cornell University Extension specialist and a USDA expert chillingly states the hazards for employees, noting: “Never enter a facility where manure is stored or where there is a suspected biogas leak as natural ventilation cannot be trusted to dilute the explosion hazard sufficiently . . . some of the gases produced are heavier than air. If a person is found unconscious at such a facility, do not enter the facility because you may be overcome as well.”

“The hydrogen sulfide that comes off these lagoons can kill pretty quickly,” said Martin. “It’s always a real concern with these hog operations that if the electricity goes out, the venting fans stop. You must have backup generators, and if there’s a storm, they really scramble to get backup power on.”

Most media reported fatalities related to manure pits did not involve biodigesters or biogas collection, but uncovered manure collection and storage. However, there is no centralized way to search federal data for injuries or deaths related to biodigesters. Worker advocates say the lack of data collection and transparency will make it even harder to ensure workers are protected as the biogas sector grows.

Food & Water Watch staff attorney Tyler Lobdell said he’s concerned that biogas “will be tacked on to large livestock facilities operated by people who have a background in raising livestock in a certain way, but we’re talking about highly specialized gas production infrastructure. It’s a very big concern that untrained, unskilled laborers will be expected to perform tasks handling explosive gases, not milking cows.”


“It’s a very big concern that untrained, unskilled laborers will be expected to perform tasks handling explosive gases, not milking cows.”


Maas countered that in modern biogas setups, there should be little need for in-house farm employees to deal with biodigesters. He noted that his sites include sophisticated remote digital monitoring, so his company is automatically notified and responds immediately if any problems are detected.

He said the majority of newer biogas operations are run by companies like his who have such technology and hire specialized employees to maintain and service biodigesters, though some will still have uncovered manure pits that are not collecting biogas.

Jim Monroe, spokesman for Smithfield, agrees, noting his company has a good safety record that also applies to its biogas operations.

“Smithfield has specific worker safety and biosecurity protocols on farms and has a best-in-class worker safety record, with incident rates below global industry averages,” he said.

He also argues biodigesters reduce air pollution that farm workers are exposed to as “they capture fugitive emissions and turn them into low-carbon fuel.”

But Wisconsin farmer Lynn Utesch isn’t convinced. He and his wife Nancy run a sustainable grass-fed beef farm in Kewaunee County, where many large dairies are using biodigesters. Utesch worries about the workers there, noting that they may be exposed to high levels of ammonia that are released from the biogas production process. Last spring, the state of Ohio sued the owners of a biodigester for unpermitted releases of ammonia.

“When they apply the manure to the land adjacent to us, your eyes burn, you can feel it in your throat, and this is after it’s been land-applied,” Utesch said. “Those workers are right there with it, that gas sits right at the ground level. No waste is supposed to be held in anaerobic conditions—nature doesn’t do that. Nobody digs a hole in the ground and puts a whole bunch of manure in it except humans—that whole system is broken.”

Family Farm Defenders’ Peck points to a state-funded biodigester in Wisconsin that has suffered multiple pipeline breaks and manure spills and a 2014 methane explosion and fire. “Methane is leaking from these things all the time, it’s like a bad Tupperware container in the back of your fridge with the top cracked open,” he said.  

Laura Hicklin, director of the Dane County Land & Water Resources Department which leases land for the biodigester, said that a different company now owns and operates the facility. “To my knowledge, there are no current safety concerns and we have not seen any repeats of the events that took place 7 years ago,” Hicklin said in an email. 

Continuing consolidation

Farm consolidation in animal agriculture has been a trend for decades, and larger companies with industrial models are now best poised to take advantage of biogas incentives.

Dairy—the main industry, along with the pork industry, generating biogas from manure—has a “pace of consolidation” that “far exceeds” the trend in other agricultural sectors, the USDA found. According to a 2020 report by the USDA, the number of licensed dairy farms fell by more than 50 percent between 2002 and 2019, even as total milk production grew. The consolidation was especially rapid in 2018–2019.

Hog farms have also seen massive consolidation. The USDA reported that in 2017, a typical hog farm sold or otherwise removed 51,300 hogs from the farm per year compared to just 1,200 in 1987—an indicator of how hog CAFOs have vastly increased in size. 

This consolidation may be spurred in part because biogas incentives are so attractive. A 2021 analysis by U.C. Davis professor Aaron Smith found that as a result of Low Carbon Fuel Standard (LCFS) subsidies, California dairy cows earn about half the amount in biogas production as they do making milk; in other words, biogas accounts for a third of the revenue generated by a given cow.

The North Carolina farm where the May spill took place had expanded its hog population despite a moratorium on CAFO expansions in North Carolina because of the state’s push to increase biodigester construction.

In Iowa, CAFOs with a biodigester are also able to expand beyond size restrictions that would otherwise apply, thanks to a law (HF 522) passed last year. “So instantly seven dairies filed to do that expansion,” said Ben Lilliston, director of rural strategies and climate change at the Institute for Agriculture and Trade Policy.

“I’ve even seen New York dairies trying to tap into the California credits, which is kind of crazy,” Lilliston continued. “There’s definitely money there, though California is going through the process of reconsidering their LCFS. This wasn’t really their plan.”

Biogas proponents say expansion and consolidation of hog and dairy operations is going to happen regardless of biogas incentives, and biodigesters reduce the greenhouse gas emissions from open manure pits while also replacing electricity generation or natural gas extraction that would create emissions.

“Dairies in the U.S. for decades have been in the process of expansion—that’s the nature of our industry right now,” Maas said. “It is in a gradual state of consolidation that’s happening everywhere in dairies with and without biodigesters.”

However, Amanda Hitt, director of the Government Accountability Project’s Food Integrity Campaign, sees biogas as one more way to justify continuing the status quo rather than making hard changes needed to increase sustainability.

“Most people are very excited about the idea that they can continue on with something potentially dangerous and bad for their health as long as there is some kind of recycle aspect to it,” said Hitt. “Though we know about all of the problems with factory farms, as soon as you hear ‘biogas’ it’s like fat-free ice cream, immediately releasing you from responsibility or any sense of guilt.”


“Though we know about all of the problems with factory farms, as soon as you hear ‘biogas’ it’s like fat-free ice cream …”


Possible safeguards

Like Peck and Utesch, advocacy groups and experts say that the risks to workers are just one more reason that the government should not incentivize or support biogas collection in animal agriculture. But if the practice is going to happen, there needs to be stricter state and federal regulation of manure pit and biodigester safety, some say.

Jessica Culpepper, director of the Food Project at the organization Public Justice, said if OSHA is ineffective, other federal agencies should step in, for example by requiring monitoring of hydrogen sulfide and other dangerous gases.

While the U.S. Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE) have some role in regulating energy facilities and their emissions, they have no say over workplace safety standards. EPA and DOE spokespeople confirmed the agencies do not track worker safety at biogas or farm operations.

However, “relating to occupational health and safety, DOE recognizes that there is a history of negative environmental and health impacts associated with some biodigester projects,” said agency spokesman Chad Smith, by email. “DOE’s Bioenergy Technologies Office recently released a Funding Opportunity Announcement to assist communities with engineering studies and feasibility analyses associated with these types of wastes and biodigester projects.”

Culpepper argues that the “EPA certainly has the authority” to monitor the air around confined animal feeding and biodigester sites. “Will they do it? I don’t know the answer. Part of our job is to push them to do it. USDA has made it very clear they want as few barriers as possible [to biogas development] as quickly as possible—which is horrifying.”

Culpepper would also like to see basic labor protections—like limits on how long people can be in confined areas, provision of personal protective equipment and assurances that people will be paid for time spent donning and doffing PPE—issued and enforced.

Berkowitz and others noted that additional requirements can theoretically be attached to participation in incentive programs.

“The government should leverage taxpayer dollars to make sure any facility getting some kind of tax incentive or funding to do this is complying with basic safety laws,” Berkowitz said.

This story was produced in partnership with Civil Eats.

Kari has written for the Energy News Network since January 2011. She is an author and journalist who worked for the Washington Post's Midwest bureau from 1997 through 2009. Her work has also appeared in the New York Times, Chicago News Cooperative, Chicago Reader and other publications. Based in Chicago, Kari covers Illinois, Wisconsin and Indiana as well as environmental justice topics.