1. In attempting to mitigate GHG emissions from factory farms, manure biogas production supports, entrenches, and expands the industrial system that creates the emissions.
2. Large factory farms with thousands of animals typically adopt the cheapest manure management systems which create the most methane.
3. Subsidies for biodigesters tend to increase the numbers of animals on factory farms; the consolidation of more animals tightly confined indoors creates more suffering, more unusable concentrated manure, and thus more pollution.
4. Large factory farms which create the most methane are subsidized, essentially providing economic support for those operations that foster the most animal suffering and the most pollution.
5. Subsidizing the largest operations ensures that smaller pasture-based farms will become even more uncompetitive; animals on pasture create little to no methane.
6. The growing collaboration between industrial animal ag and carbon fuel producers offers to both a unique greenwashing opportunity that transforms the intense confinement of animals into an accepted baseline, and further confuses consumers about the environmental impacts of animal-sourced foods.
In an attempt to mitigate methane emissions from factory farms, biogas production supports, entrenches, and expands the very industrial system that creates the emissions to begin with.[1]
Moreover, the subsidies that help mitigate this one negative externality reinforce many others, including animal suffering, water pollution, massive water usage, and land and soil degradation.[2]
Not only do manure biogas digesters currently address just a small sliver of animal ag’s methane emissions, there is evidence that they increase other types of emissions, including ammonia.[3,4]
See question below: How and why do factory farms choose manure management systems that produce methane?
See questions below about the impacts on animal welfare and the environment.
See, Manure Biogas Fundamentals [question: How much GHG emissions are at stake?]
See question below: Do manure biogas anaerobic digesters increase ammonia emissions?
Yes, several reports and non-profit studies document that factory farms with biodigesters tend to increase the number of animals per operation.[1-4]
This is naturally the case, since it is widely understood that the larger the operation, the more likely it is that a manure biogas digester will be profitable.[5]
Magesh, V., et al., (2025). Do Methane Mitigation Incentives Intensify Livestock Production? Evidence from California, 2016-2025, p. 4. [“We estimate that the presence of a digester and attendant incentives are associated with an increase in barn area by 5,398 square meters three years after digester construction is anticipated. This is equivalent to 860 additional mature dairy cows housed three years after digester construction is anticipated.”]
Erin Jordan (March 19, 2026). ‘More manure means more energy’: Iowa dairies with biogas digesters are growing their herds, which concerns water quality advocates. The Gazette. [Review of state data shows 23% increase in the number of animals]
Waterman, C. & Armus, M. (2024). Biogas or Bull****? The Deceptive Promise of Manure Biogas as a Methane Solution. Friends of the Earth, Table B-1, p. 59. [“For the 73 facilities in our data set, we estimated 84,201 additional dairy cows were added between the starting and ending year, which represents an annual year-over-year herd size increase of 3.7%.”]
Molander, C. & Armus, M. (2024). Making a Bad Situation Worse. Friends of the Earth & Socially Responsible Agriculture Project, p. 6. [“In Kewaunee County, our research shows that on average, herd sizes at CAFOs with a digester grew by 58%. This represents an astonishing annual year-over-year herd size increase of 5.2% and reflects national trends.”]
U.S. EPA AgSTAR (2020). Project Development Handbook, 3rd ed., 430-B-20-001, p. 1-6. [“Successful farm-based AD/biogas systems typically operate with at least 500 cows in dairy operations or at least 2,000 hogs in swine operations… dairy farms having greater than 1,000 animals or hog farms having greater than 5,000 animals increases the likelihood of project success.”]
Yes, these subsidies tend to place smaller, potentially more humane or sustainable operations at a further competitive disadvantage.[1-5] They don’t have access to biogas grants and loans or to the stream of future revenues.
The irony is that the dairy industry works hard to convince consumers that their milk comes from small with contented cows grazing by red barns, as depicted on millions of consumer packages. The reality of tightly confined animals and massive manure lagoon digesters makes this image even harder to sell.
Fingerman, K., et al., (2025). Risks of crediting carbon offsets in low carbon fuel standards: lessons learned from dairy biomethane. Energy Policy, 206, 114738, p. 4. [“This risks leaving behind small and medium-sized farms which are often already implementing more sustainable manure management strategies and therefore have no point source methane production to abate.”]
Martin, J. (2024). Something Stinks: California Must End Manure Biomethane Accounting Gimmicks in Its Low Carbon Fuel Standard. Union of Concerned Scientists. [“What started as a clever way for California regulators to indirectly support expensive dairy digester projects in California is putting smaller farms across the United States at a disadvantage, especially those that use more sustainable manure management strategies, and potentially pushing them out of the business entirely.”]
Lazenby, R. (2024). Mitigating Emissions from California’s Dairies. UCLA Emmett Institute on Climate Change and the Environment, p. 16. [Regarding the California dairy farms where manure management systems are not producing methane: “Rather than devise a mitigation intervention applicable to these farms, CARB simply excludes them from the program if their practices do not match those in the reference scenario. This is unfortunate, because it limits eligibility for the lucrative LCFS credits to operations with the most polluting practices (those that match the reference scenario).”]
Waterman, C. & Armus, M. (2024). Biogas or Bull****? The Deceptive Promise of Manure Biogas as a Methane Solution. Friends of the Earth, p. 7. [“…pasture-based producers who are using the best (least methane-producing) manure management strategies in the first place are not able to produce and sell manure biogas since they do not collect waste in methane producing lagoons, making it even harder for them to compete with CAFOs.”]
Blanca Begert (January 28, 2026). Are Incentives for Fuel Made from Livestock Manure Leaving Small Farmers Behind? Inside Climate News
Factory farms, especially large operations, have chosen to implement liquid manure management systems, despite the accompanying production of methane.[1]
The confinement of large numbers of animals in small areas encouraged factory farms to develop liquid, or slurry systems that could efficiently handle and store vast amounts of low-value and mostly unusable waste.[2,3] Most operations mix manure with huge volumes of water and then store the liquid or slurry in lagoons, tanks, or pits, which is where most of the methane is created.[4] This system decreases long-term expenses due to ease of handling, storing, and transporting large manure volumes, while reducing labor costs.[5-7]
There are alternative methods, as the EPA notes: “Some dairy manure is handled as a solid, stored in piles or stacks, spread daily, or left to lie in pastures or ranges where animals graze. These management practices generate minimal methane and are common for smaller operations.”[8] There is little to no methane produced by animals on pasture.[9]
Illogical as it may seem, governmental programs and policies were developed to pay or subsidize those factory farms that choose to handle their manure in liquid systems that produce more methane.[10] The more they create, the more money they can make through mitigation.[11]
U.S. EPA (2025). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2023, EPA 430-R-25-003, p. 5-14. [“When livestock manure is stored or treated in systems that promote anaerobic conditions (e.g., as a liquid/slurry in lagoons, ponds, tanks, or pits), the decomposition of the volatile solids component in the manure tends to produce CH4.”]
Long, C. M., et al., (2018). Use of manure nutrients from concentrated animal feeding operations. Journal of Great Lakes Research, 44(2), 245-252, p. 6. [“Because more manure is generally produced by a CAFO than can easily be used, it is often treated as waste rather than as a valuable replacement for inorganic fertilizer.”]
See, Economics of Manure
U.S. EPA (2021). Anaerobic Digestion on Dairy Farms, p. 1. [“Flush collection systems use large volumes of water to collect and remove manure from barns and milking parlors, while scrape collection systems remove manure from barns and alleyways. These systems move the manure into long-term storage in anaerobic lagoons, tanks, or earthen ponds under anaerobic conditions where the manure releases methane.”]
Wainer, A., et al., (2025). Deconstructing the Livestock Manure Digester and Biogas Controversy. Current Environmental Health Reports 12:43, p. 1. [“Over recent decades, the US livestock and poultry sectors have shifted to larger, more industrialized operations and have become more concentrated in specific regions of the country. Concurrently, manure management strategies have adapted to handle larger quantities of animal waste.”]
Pfost, D. L., et al., (2000). Anaerobic lagoons for storage/treatment of livestock manure. University of Missouri Extension, Publication EQ387, p. 1. [“Many livestock producers with confinement operations handle their animal waste as a liquid because of the laborsaving advantages.”]
UMass (2002) Dairy BMPs: A Handbook for the Dairy Industry in Massachusetts, CDLE Pub. 11-55, UMass Extension Crops, Dairy, Livestock, Equine. [“Typical dry storage facilities are designed to handle the solid manure from dairy cattle separated or scraped solids from dairy operations and other materials such as bedding. Disadvantages include: More labor in manure collection and handling (mechanical vs. hydraulic handling) than liquid storage… Labor and equipment requirements for the larger number of loads to haul and spread for land application.”]
U.S. EPA (2021). Anaerobic Digestion on Dairy Farms, p. 1.
U.S. EPA (2025). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2023, p. 5-14. [“When manure is handled as a solid (e.g., in stacks or drylots) or deposited on pasture, range, or paddock lands, it tends to decompose aerobically and produce CO2 and little or no CH4.”]
U.S. EPA (June 2018). Market Opportunities for Biogas Recovery Systems at U.S. Livestock Facilities, EPA-430-R-18-006, p. 4. [“A biogas capture and use project is most likely to succeed where manure is collected as a liquid, slurry, or semi-solid and stored in open pits, ponds, or lagoons. Because the vast majority of large dairy and swine operations in the United States use liquid or slurry manure management systems, biogas production potential at these operations is high, as are the potential greenhouse gas reductions if biogas recovery systems are implemented.”]
Lazenby, R. (2024). Mitigating Emissions from California’s Dairies. UCLA Emmett Institute on Climate Change and the Environment, p. 17. [“This means that the more emissions they generate, the more they can capture, the more reductions they can claim publicly, and the more revenue they obtain through Low Carbon Fuel Standard (LCFS) credits.”]
Building manure digesters has the net effect of normalizing, increasing, and entrenching the intense confinement and mistreatment of dairy cows and pigs. (See other pages for details on factory farming’s manure-filled housing conditions, cramped quarters, and the long list of routine abuses, including mutilations and amputations, inflicted on these animals.)[1-3]
Normalizing confinement and mistreatment – In the extensive literature on manure biogas, the mentions of animal housing conditions, intense confinement, and routine mistreatment are almost nil.[4] The numbers of cows or pigs per operation are reported as if they were barrels of oil or cars on an assembly line.
Increasing numbers of animals and intensity of confinement – Factory farms that build digesters tend to increase the numbers of animals per operation.[5] And larger factory farms are more likely to confine the animals, increasing the number of cows that never get out to pasture and the number of sows in gestation crates.[6,7] Choices about bedding materials are determined by what is best for digester functioning.[8,9]
Entrenching confinement systems – Given the large capital investments, it can take 20 years or more to recoup initial costs, fixing in place the brutal confinement of animals.[10,11] The power of the industry grows as operations with biogas systems create alliances with fossil fuel companies, further reducing the likelihood of improvements for animals.[12]
Smaller farms at a disadvantage – Added income streams for large producers tilt the playing field away from producers that might offer more humane treatment, putting them at a further competitive disadvantage.[13,14] The EPA suggests that the likelihood of success and profitability is increased on dairy farms with more than 1,000 cows and pig farms with more than 5,000 pigs.[15]
Societal stamp of approval – Giving grants, loans, offsets, and tax breaks directly to huge factory farms is a societal stamp of approval on the underlying animal treatment. These support programs are essentially stating that large factory farms and their abusive treatment of animals are here to stay, so we might as well make the best of it.
Aura of sustainability – These endorsements are enhanced by the aura of sustainability that accompanies efforts to reduce GHG emissions. Consumers may assume that a concern for the welfare of animals accompanies a concern about emissions, thereby bringing even less attention to their tortured lives.
For info on housing conditions, see, Housing & Space Allotments – Cattle & Dairy and Housing Conditions & Space Allotments – Pigs. For info on amputations and mutilations, see, Mutilations & Amputations – Dairy Cows and Mutilations and Amputations – Pigs
For a surprisingly candid inside view of the wide range of abuses heaped upon dairy cows on factory farms see this overview from the American Association of Bovine Practitioners (veterinarians), including a past president. [Cook, N., et al., (September 2023). The evolution of dairy cattle welfare, American Assoc. of Bovine Practitioners, AABP Proceedings, Vol 56, No. 2, p. 47. This long but still incomplete list of reviewed dairy welfare issues include zero-grazing, dehorning and castration without anesthesia, quantity-restricted diets for young calves, lameness and hock injuries, use of tie stalls and stanchions, cow-calf separation at birth, raising calves in individual pens, killing surplus male and female calves at birth, long transport times for young calves, and the failure to cull spent cows. “All of these issues are shocking to the customer once they are made aware of them. Believe us when we say that it is not if awareness grows, but simply when, given the rate of consumption of social media.” Unfortunately, manure biogas increases the likelihood that all these practices and more (artificial insemination, teat removal, ear tagging, unnatural diets, built-in painful conditions like mastitis) will stay firmly in place and that more dairy cows will be subjected to them for decades to come.
For an overview of a typical dairy cow’s tormented life, see, Marina Bolotnikova (April 24, 2025). The life of a dairy cow. Vox.
Only the rare non-profit report considers the impacts of digester construction on animals. Therefore, parts of this answer are lightly referenced and mostly intuitive. With biogas digesters as an important revenue stream and a contentious policy issue, the welfare of the animals slips further down the list of considerations.
Magesh, V., et al., (2025). Do Methane Mitigation Incentives Intensify Livestock Production? Evidence from California, 2016-2025. [“We estimate that the presence of a digester and attendant incentives are associated with an increase in barn area by 5,398 square meters three years after digester construction is anticipated. This is equivalent to 860 additional mature dairy cows housed three years after digester construction is anticipated.” For further references, see subsequent question “Do factory farms with digesters tend to get bigger?”]
MacDonald, J. M., et al., (2020). Consolidation in US dairy farming. USDA Economic Research Service, Report No. 274, Table 5, p. 22. [90% of dairy factory farms with more than 1,000 cows “do not graze cows” whereas 23% of farms with 10 to 49 cows “do not graze cows.”]
USDA APHIS (July 16, 2024). Swine Part I: Reference of Management Practices on Large-Enterprise Swine Operations in the U.S. https://www.aphis.usda.gov/swine-2021-part-i-reference-management-practices-large-enterprise-swine-operations-united-states [See: Individual Tables, Table B.1.a. Notes that 38% of “large operations” with >500 sows use group housing, 82% with 250-499 sows, and 52% with <250 sows.]
U.S. EPA (updated 2025) Is Anaerobic Digestion Right for Your Farm? [“Biogas production is best suited for farms that regularly collect liquid, slurry or semi-solid manure with little or no bedding.”]
U.S. EPA AgSTAR (2018). Market opportunities for biogas recovery systems at US livestock facilities. See Figure 2, p. 7. [“Bedding added” is “not recommended” for biogas production.]
Ben Laine (2025) Economic Sustainability of Dairy Digesters. Terrain, p. 3. [“…expected operating life of at least 20 years.”]
Waterman, C. & Armus, M. (2024). Biogas or Bull****? The Deceptive Promise of Manure Biogas as a Methane Solution. Friends of the Earth, p. 7. [“…it will take years or decades for biogas companies and CAFO operators to recoup initial costs. Therefore, government support for building out manure biogas now risks locking us into the factory farming and fossil fuel systems that manure biogas production depends on for decades to come.”]
Phred Dvorak (February 19, 2022) California’s Green-Energy Subsidies Spur a Gold Rush in Cow Manure. Wall Street Journal. [“Together with European energy giants BP and Total Energies SE, Clean Energy is pouring hundreds of millions of dollars into gas production on dairy farms to milk that advantage. A host of developers, financiers and carbon-conscious corporations, from Chevron Corp. to Amazon.com are looking to buy or produce the fuel as well.”]
Martin, J. (2024). Something Stinks: California Must End Manure Biomethane Accounting Gimmicks in Its Low Carbon Fuel Standard. Union of Concerned Scientists. [“What started as a clever way for California regulators to indirectly support expensive dairy digester projects in California is putting smaller farms across the United States at a disadvantage, especially those that use more sustainable manure management strategies, and potentially pushing them out of the business entirely.”]
Lim, T. et. al., (2023). Increasing the Value of Animal Manure for Farmers, USDA ERS, AP-109, p. 56. [“Anaerobic digesters, though technically feasible for many U.S. farms, are often limited in their application to larger scale operations (500 cows or more) due to relatively high capital cost per animal. Even with subsidized support offsetting initial capital investments, small to mid-sized dairy farms lack the economies of scale operationally necessary to generate a positive return of investment and face higher uncertainty associated with an economic value of benefits, system reliability, rates of return, and risk of lost capital relative to large farming operations.”]
U.S. EPA AgSTAR (2020). Project Development Handbook, 3rd ed., 430-B-20-001, p. 1-6. [“Successful farm-based AD/biogas systems typically operate with at least 500 cows in dairy operations or at least 2,000 hogs in swine operations… dairy farms having greater than 1,000 animals or hog farms having greater than 5,000 animals increases the likelihood of project success.”]
The central environmental problem of factory farms is the concentration of huge amounts of unusable manure in very small areas without enough cropland to assimilate the nutrients, leading to nutrient pollution.[1,2] The irony of subsidies for manure biogas digesters is that they likely increase the overall levels of nutrient pollution.[3]
Pollution swapping – Due to a societal awareness of climate change and a relative lack of awareness of nutrient pollution, the net effect of government support for anaerobic digesters is to replace one kind of pollution with another.[4,5] Digesters mitigate a very small share of a potent climate pollutant (methane) by ensuring that a very large share of other air and water pollutants (nitrogen and phosphorus) will be both increased and entrenched.
Nutrient pollution – Nutrient pollution is one of the greatest threats to the environment, impacting every aspect of life on earth.[6] Globally, nitrogen pollution is the planetary boundary most clearly in the “high-risk” zone.[7] Nutrient pollution from manure and feed crops is the primary driver of the pollution of U.S. waterways.[8] Factory farm manure is the primary source of ammonia emissions, a lethal form of nutrient pollution. (See next question)
Support for digesters increases nutrient pollution by: 
Placing more animals and thus more manure in concentrated areas – exactly the opposite of what is needed for nutrient pollution control. Promoting the spread of water-based manure management systems that increase nutrient pollution.[9] Entrenching polluting systems with capital spending programs with long payback periods.[10] Increasing ammonia production during storage and digestate handling. (See next question)
The full array of pollutants from vast volumes of concentrated manure includes a wide range of other contaminants.[11] Additionally, outsized land and water usage is another important component of the environmental implications of entrenching the factory farming system.[12]
See, Manure Pollution Overview and Economics of Manure [Note: an argument could be made that the central environmental problem of the factory farming system is the allocation of most of the country’s best cropland to the production of cheap monoculture feed crops with all the accompanying damages. Still, for factory farms themselves, the number one cause of environmental problems is the massive volume of concentrated manure.]
U.S. EPA (2004). Risk Assessment Evaluation for Concentrated Animal Feeding Operations. EPA/600/R-04/042, p. 2. [As the EPA explained over twenty years ago: “Underlying all of the environmental problems associated with CAFOs is the fact that too much manure accumulates in restricted areas. Traditional means of using manure are not adequate to contend with the large volumes present at CAFOs.”]
Note: Most studies of this issue compare nutrient pollution impacts before and after anerobic digesters are built. And though they largely concede that nutrient pollution risks are elevated, they don’t include in their studies the key long-term drivers, which we note below: digester support tends to consolidate more animals, creating more concentrated manure, using water-based manure management systems that create more ammonia, with capital spending that entrenches these systems for decades to come.
See, for example, the huge discrepancy between media coverage of climate change versus biodiversity loss (the two “core boundaries“ in the planetary boundary framework), despite similar levels of coverage in scientific articles. [Legagneux, P., et al., (2018). Our house is burning: discrepancy in climate change vs. biodiversity coverage in the media as compared to scientific literature. Frontiers in ecology and evolution, 5, 297310.]
Wainer, A., et al., (2025). Deconstructing the Livestock Manure Digester and Biogas Controversy. Current Environmental Health Reports, 12:43, p. 5. [“Although evidence suggests manure digesters could reduce odors and methane, the potential for elevated ammonia emissions and new hazards from biogas combustion could result in “pollution swapping.”]
Richardson, K., et al., (2023). Earth beyond six of nine planetary boundaries. Science advances, 9(37), eadh2458. [See the planetary boundary labeled “biogeochemical flows.” And see, Nutrient Pollution of Waterways]
Caesar, L., et al., (2024). Planetary Health Check Report 2024. Potsdam Institute for Climate Impact Research, Potsdam, Germany, see, Figure 1, p. 5.
See, Animal Ag’s Contributions to Water Pollution [According to our calculations, “Industrial animal agriculture is the primary contributor to the failing grades of U.S. waterways, responsible for about 50% of nutrient pollution – the leading cause of U.S. water pollution.”]
Aillery, M. P., et al., (2005). Managing manure to improve air and water quality. USDA Economic Research Report 9, Table 2-1, p. 9. [Nitrogen losses from flush barn systems are far in excess of traditional daily spread of solid manure.]
Ben Laine (2025). Economic Sustainability of Dairy Digesters. Terrain, p. 3.
U.S. EPA (2013). Literature Review of Contaminants in Livestock and Poultry Manure and Implications for Water Quality. EPA 820-R-13-002, p. 1 & Table 1-1, Key pollutants from livestock operations and animal manure. [“Manure often contains pathogens (many of which can be infectious to humans), heavy metals, antimicrobials, and hormones that can enter surface water and ground water through runoff and infiltration potentially impacting aquatic life, recreational waters, and drinking water systems.”]
See, for example, Feed Crop Water Usage [question: What is the share of total U.S. water consumption attributed to hay, corn, and soybeans?] [Alfalfa/hay production is responsible for ~23% of total U.S. water consumption (mostly used for dairy and almost entirely used for animal ag)]
Most evidence suggests that digester systems increase ammonia emissions.[1-5] Because of the wide range of manure management systems and digester construction types and sizes, it is difficult for researchers to state this definitively.
Ammonia (NH3) is a deadly gas and a form of nitrogen pollution, with about two-thirds coming from animal agriculture.[6,7] Dairy farms are responsible for a huge share of national ammonia emissions, perhaps about a quarter.[8]
Ammonia is considered by many researchers the most damaging agricultural pollutant.[9-11]
Ammonia and the entire array of poisonous gases from factory farms are almost entirely unregulated by the EPA.[12,13]
Aguirre-Villegas, H. A., et al., (2014). From waste-to-worth: energy, emissions, and nutrient implications of manure processing pathways. Biofuels, Bioprd. Bioref. 8:770-793, p. 789, Abstract. [“Ammonia emissions are increased in all pathways by 2% for solid-liquid separation, 40% for anaerobic digestion, and 44% for anaerobic digestion plus solid-liquid separation.”]
Holly, M. A., et al., (2017). Greenhouse gas and ammonia emissions from digested and separated dairy manure during storage and after land application. Agriculture, Ecosystems and Environment 239, 410-419, p. 411 & p. 417. [“While there exists a potential for GHG emissions reductions, a tradeoff may exist in using digestion to mitigate manure GHG emissions, as some of the changes in the manure composition can promote NH3 emissions following digestion… the ammonia losses from storage of the digested and separated manure is still greater than the raw manure alone.”]
Harper, L. A., et al., (2010). The effect of biofuel production on swine farm methane and ammonia emissions. Journal of Environmental Quality, 39(6), 1984-1992, Abstract. [“…NH3 emissions in the biofuel farms increased by 46% over the conventional farms. These studies show that what is considered an environmentally friendly technology had mixed results and that all components of a system should be studied when making changes to existing systems.”]
Roger Nkoa (2014). Agricultural benefits and environmental risks of soil fertilization with anaerobic digestates: a review. Agronomy for Sustainable Development, 34 (2), Abstract. [“…anaerobic digestates have higher NH3 emission potential than undigested animal manures and slurries and, consequently, pose a greater risk to the broad environment…”]
Pederson, J. & Hafner, S. D. (2023). Ammonia emissions after field application of anaerobically digested animal slurry: Literature review and perspectives. Agriculture, Ecosystems and Environment 357, 108697, p. 2 & p. 7. [“On average, there is an increase in ammonia emissions during storage due to digestion, but for nitrous oxide there is no clear difference. … Digesting slurry increases the risk of high ammonia emissions from both storage and land application.”]
U.S. EPA (2024). 2020 NEI Supporting Data and Summaries – Data Queries for Sector Summaries. [Query: National/Ammonia NH3/Livestock Waste (49.2%), fertilizer application (33.5%). Of the 33.5% due to fertilizer application, we estimate at least half is from feed crops. Therefore, 49.2% + 16.8% = 66%]
See, Animal Ag Ammonia & PM2.5 and see, Sarah Kaplan (May 10, 2021). Air pollution from farms leads to 17,900 U.S. deaths per year, study finds. Washington Post.
Rotz, A., et al., (2021). Environmental assessment of United States dairy farms. Journal of Cleaner Production, 315, 128153, p. 11. [“Perhaps the greatest environmental concern is that of NH3 emissions, where dairy farms may emit as much as 24% of that estimated for the whole country.”]
Rotz, C. A., et al., (2014). Ammonia emission model for whole farm evaluation of dairy production systems. Journal of environmental quality, 43(4), 1143-1158, p. 1143. [“Gaseous emissions from animal agriculture … include greenhouse gases, volatile organic compounds, and specific toxic compounds, of which ammonia (NH3) is the most important.”]
Giannadaki, D., et al., (2018). Estimating health and economic benefits of reductions in air pollution from agriculture. The Science of the Total Environment, 622–623, 1304–1316, p. 1305. [“The main pollutant from agricultural activity is ammonia (NH3)…”]
Hill, J., et al., (2019). Air-quality-related health damages of maize. Nature Sustainability, 2(5), 397-403. [Report estimates the PM2.5 pollution costs of corn production (the primary animal feed) at about 8 times the GHG damages of corn production. Ammonia is a precursor gas to PM2.5, the most damaging component of air pollution to human health.] See also, Animal Ag Ammonia & PM2.5
U.S. EPA (updated August 15, 2025) CERCLA and EPCRA Reporting Requirements for Air Releases of Hazardous Substances from Animal Waste at Farms.
Saifuddin, M., et al., (2025). Monitoring, modeling, and regulating air pollution from industrial animal agriculture in the United States. npj Clean Air, 1(1), 32, p. 2. [“Existing literature suggests that many AFOs generate emissions well above relevant statutory air pollutant thresholds. However, for over two decades, EPA has functionally excused AFOs from compliance with air pollution statutes…”]
Almost no digesters would be built without government support via grants, loans, and technical assistance.[1,2] Although manure biogas is promoted as an energy source and revenue stream for a farm, one credit industry report suggests that the costs “significantly exceed the value of the gas produced,” with government sponsored carbon offsets and tax credits making up the bulk of the revenue.[3] For this reason, digesters are inherently unstable economically, mostly dependent on policies that are subject to change.[4]
The building costs of dairy digesters can be in the range of ~$2 million to ~$12 million, based on the digesters supported by the California Department of Food and Agriculture (CDFA). The average cost of the 143 digesters was ~$5.3 million.[5]
In 2026, the USDA discontinued REAP grants and loans for biodigesters until further notice.[6,7] Prior to that, federal grant and loan guarantees could be up to 75% of total project costs.[8]
The recent federal grant discontinuation puts California’s CFDA program as the primary driver of biodigester support. If that policy underwent significant change, the entire system could be threatened, potentially stranding built capital.[9] The profitability of many dairy digesters now rests on the unusual, and to many, inexplicably large credits from the low carbon fuel standards program (LCFS).[10] In 2023, dairy biogas contributed almost 20% of the credits in the LCFS program, yet it provided less than 1% of energy used for transportation.[11]
Lim, T. et. al., (2023). Increasing the Value of Animal Manure for Farmers. USDA ERS, AP-109, p. 54. [“Growth in anaerobic digester use has occurred because of grant and subsidy support from governmental agencies and organizations.”]
Badzmierowski, M., et al., (2025). Analysis of US manure management and recommendations to mitigate associated greenhouse gas emissions. Working Paper. Washington, DC: World Resources Institute, p. 13. [“Most digesters today rely on California’s Low Carbon Fuel Standard, making them vulnerable to policy changes.”]
Ben Laine (2025). Economic Sustainability of Dairy Digesters. Terrain, p. 3. [“To be sure, running manure through an anaerobic digester is an expensive way to generate natural gas. The costs significantly exceed the value of the gas produced. This approach is only currently feasible when the gas is used as transportation fuel and generates valuable Low Carbon Fuel Standard (LFCS) credits, Renewable Identification Number (RIN) credits or similar.”]
Badzmierowski, M., et al., (2025), p. 13. [“Most digesters today rely on California’s Low Carbon Fuel Standard, making them vulnerable to policy changes.”]
California Department of Food and Agriculture (CDFA) (2025). Dairy Digester Research and Development Program – Report on Funded Projects 2015-2025, Table 5, p. 20.
USDA (January 1, 2026) Letter Re: 90 Day Administrative Pause on Biodigesters and Controlled Environment Agriculture Applications Pending Portfolio Performance Review, posted by Agri-pulse. [“Pause the acceptance or awarding of any biodigester or controlled environmental agriculture loan guarantee for a period of 90 days or until further guidance has been directed. … Twenty-one loans for anaerobic biodigesters which make up $386.4 million are currently seeing $102.6 million or 27% in delinquency.”]
USDA (March 31, 2026). Rural Business Cooperative Service Update on the Status of the Rural Energy for America Program. https://www.rd.usda.gov/programs-services/energy-programs/rural-energy-america-program-energy-audit-renewable-energy-development-assistance-grants [“…the Rural Energy for America Program will not be making further grant awards until the new regulations are in effect.”]
USDA (April 2020). Rural Energy for America Program Renewable Energy Systems & Energy Efficiency – Improvement Guaranteed Loans – Immediate Measures to Support Rural Communities Affected by COVID-19. [“Combined grant and loan guarantee funding up to 75% of total eligible project costs.”]
Wainer, A., et al., (2025). Deconstructing the Livestock Manure Digester and Biogas Controversy. Current Environmental Health Reports, 12:43, p. 6. [“Evidence suggests manure digesters can be economically viable for some large dairy and swine operations if they can secure government funding for construction costs and find diversified revenue streams such as the Low Carbon Fuel Standard (LCFS) credit market, but changes in either the subsidy market or regulations could quickly change the financial picture.”]
Martin, J. (2024). Something Stinks: California Must End Manure Biomethane Accounting Gimmicks in Its Low Carbon Fuel Standard. Union of Concerned Scientists. [“A negative carbon intensity (CI) score would suggest an almost magical climate solution that pulls several carbon dioxide molecules from the atmosphere for each one that comes from the tailpipe of a truck running on dairy biomethane. Unfortunately, this is far from the truth.”]
Aaron Smith (Jan. 22, 2024). Cow Poop is Now a Big Part of California Fuel Policy. Ag Data News. [“In the most recent LCFS data, dairy biogas contributed almost 20% of the credits in the LCFS program, yet it provided less than 1% of energy used for transportation. Dairy biogas has an outsized impact in the LCFS because it is treated very differently than most fuels.”]
Very broadly estimated, federal and state subsidies to date including grants and loan guarantees are probably on the order of about $2 billion.[1] The 2 major funding programs have been the USDA’s Rural Energy for America Program (REAP) and the California Department of Food and Agriculture’s (CDFA) Dairy Digester Research & Development Program (DDRDP).
Rural Energy for America Program (REAP) – The Inflation Reduction Act included a large infusion of funds for manure biogas, but we are not aware of federal estimates of total amounts.[2] Most estimates of REAP spending come from non-profit analyses including FOIA requests. From 2021 to 2025, the program awarded $257 million to 55 new manure digesters in grants and loan guarantees.[3] The year “2023 set a record for REAP grants awarded to biogas and anaerobic digesters, reflecting a roughly 2,600 percent increase from 2022 to 2023.”[4] A recent USDA letter has put a pause on all REAP funding for biodigesters while also noting that “Twenty-one loans for anaerobic biodigesters which make up $386.4 million are currently seeing $102.6 million or 27% in delinquency.”[5,6]
California Department of Food and Agriculture (CDFA) – From 2015 through 2025, CDFA awarded grants totaling ~$231 million for 143 dairy digester projects.[7] It is likely that ~$1.1 billion in Low Carbon Fuel Standard credits (LCFS) has been distributed to dairy factory farms in California and throughout the country.[8,9] An additional ~$400 million has been granted by other California public agencies.[10]
Tax Credits – The Inflation Reduction Act allowed digester investments to qualify for renewable energy “Investment Tax Credits.”[11] This benefits some of the largest oil companies in the U.S. (Shell, BP, and Chevron) which have financed or own many digesters.[12,13] For both 2023 and 2024, a broad estimate of the value of the tax credits for all biogas operations is ~$100 million per year, with similar levels expected in subsequent years.[14]
There are many other support programs including the USDA’s EQUIP program and tax credits and loans through a variety of state and federal programs.[15]
Note: We are not aware of credible estimates for this figure. The USDA and EPA are not transparent about funding to date, so the REAP programs are broad estimates. See, for example Molander, C. & Armus, M. (2024). Making a Bad Situation Worse. Friends of the Earth, p. 20. [“Broadly however, the lack of transparency into digester operations makes it challenging to identify all of their funding sources. For example, the EPA AgSTAR database, the main federal source for tracking digesters, only provides a “yes/no” column for USDA funding, does not report more granular funding or profit sources, and does not include all digesters. On the whole, there is a shocking lack of mandated disclosure and reporting, despite the provision of significant public tax dollars.”]
Wakeman, D. & Fingerman, K. (2023). Waste stream to revenue stream. Center for Food Safety, p. 6. [“On its website, REAP expresses an intent to obligate over a billion dollars to projects within the next two fiscal years. While we know that digester projects in California have received funding from this program in the past, the exact amount of funding provided in total is not available to the public.”]
Friends of the Earth et al., (2026). Petition to the USDA, p. 6. https://foe.org/wp-content/uploads/2026/01/2026-01-14-REAP-Digester-Petition_FINAL.pdf [This petition estimates that from 2021 through 2025, grants and loan guarantees of “about $257 million went to 55 new manure digesters.”]
Farm Forward (2025). Gaslit by Biogas: Big Ag’s Reverse Robin Hood Effect, p. 11. [“Our analysis of USDA’s Rural Energy for America Program (REAP), which got a huge infusion of funds from the IRA, along with publicly available documents related to IRA tax credits, reveals that in 2023 alone, the IRA provided over $150 million in subsidies to biogas operations.” This figure includes “tax credit estimates, and the value of loan guarantees.”]
USDA Rural Development, Rural Energy for America Program Renewable Energy Systems & Energy Efficiency Improvement Guaranteed Loans. https://www.rd.usda.gov/programs-services/energy-programs/rural-energy-america-program-renewable-energy-systems-energy-efficiency-improvement-guaranteed-loans#overview
USDA (January 1, 2026) Letter Re: 90 Day Administrative Pause on Biodigesters and Controlled Environment Agriculture Applications Pending Portfolio Performance Review, posted by Agri-pulse. [“Pause the acceptance or awarding of any biodigester or controlled environmental agriculture loan guarantee for a period of 90 days or until further guidance has been directed.”]
California Department of Food and Agriculture (CDFA) (2025). Dairy Digester Research and Development Program – Report on Funded Projects 2015-2025, p. 2. [“CDFA has awarded a total of approximately $231 million for 143 dairy digester projects, with approximately $529 million provided in matching funds by grant awardees.”]
Fingerman, K., et al., (2025). Risks of crediting carbon offsets in low carbon fuel standards: lessons learned from dairy biomethane. Energy Policy, 206, 114738, pp. 1-2. [“LCFS credit generation for manure digester projects has grown 1000% since 2020, and has generated more than a billion dollars’ worth of credits.” This report refers to a CARB website to which we don’t have access.]
Wakeman, D. & Fingerman, K. (2023), p. 7. [“Since digesters first generated credits in 2017, an estimated $1.1 billion have gone to farms all over the country participating in the market.”]
Wakeman, D. & Fingerman, K. (2023), Table 1, p. 9.
Aaron Lang & Kevin Chen (December 9, 2024). A Boon for Biogas: Treasury’s Final Section 48 ITC Rules Resolve Key Concerns for Biogas and RNG Projects. Foley Hoag. [“The Investment Tax Credit (ITC) applies to a broad range of clean energy projects, including biogas projects, which were added to the ITC by the Inflation Reduction Act.”]
Phred Dvorak (February 19, 2022). California’s Green-Energy Subsidies Spur a Gold Rush in Cow Manure. Wall Street Journal. [“Together with European energy giants BP and Total Energies SE, Clean Energy is pouring hundreds of millions of dollars into gas production on dairy farms to milk that advantage. A host of developers, financiers and carbon-conscious corporations, from Chevron Corp. to Amazon.com are looking to buy or produce the fuel as well.”]
Food & Water Watch (2024) The Big Oil and Big Ag Ponzi Scheme: Factory Farm Gas, p. 2. [“ An industry around designing and building digester projects has sprung up alongside this money, with the top independent firms growing 300 percent from 2019 to 2020. Between three of the largest oil companies in the U.S., there are five joint ventures with these types of factory farm gas companies, and they own or finance up to 143 digesters or upgrading facilities.”]
Joint Committee on Taxation (December 11, 2025). Estimates of Federal Tax Expenditures for Fiscal Years 2024-2028, JCX-59-23, [See Table 1 for Qualified biogas property. Prior year’s (2023) report also shows $.1 billion]
Michael Happ (April 2024). Costly Versus Cost-Effective: How EQIP can be improved to serve more farmers and the climate. Institute for Agriculture & Trade Policy, p. 3. [The average contract size for a manure digester was $408,537 awarded to 5 operators, for a total of more than $2 million.]
An imagined scenario illustrates the contradictions and flawed logic behind manure biogas subsidies. A town negotiates with a band of teenagers who are abusing the local park. They tear up the lawn, pee in the pond, leave faucets running all night, and disturb the neighbors. The mayor (who happens to own the local hardware store) offers the group a stipend to help specifically with re-seeding one section of the lawn.
Encouraged by the new income stream, more teens join the group, and they double-down on the havoc, while still re-seeding. As they dig up more of the park, the town increases the area of lawn for paid re-seeding. Some previously well-behaved teens can’t find summer jobs, so they join the re-seeding work and get pulled into a culture of destruction. The local paper runs a piece with pictures of healthy new lawns. The hardware store has a thriving seed and lawn tool business. Local citizens that use the park are stunned by the developments.