Anaerobic Digestion Facilities Processing Food Waste in the U.S. (2020 & 2021)

On this page:

Background and Survey Process
Survey Responses, Operational Dates, and Status
Food Waste Processing
Non-Food Feedstock Processing and Available Capacity
Tipping Fees
Biogas Production and Use
Operational Specifications and Pre-processing Activities
Digestate Uses
Annual Survey Results
Related Links and Resources

Background and Survey Process

In 2014, EPA began building a dataset of names and locations of anaerobic digestion facilities processing food waste to better understand the practice and prevalence of food waste digestion in the U.S. EPA recognized that data showing the feasibility of using anaerobic digestion to process food waste is important for states, communities, and others working to divert food waste from landfills and combustion facilities. In December 2016, EPA was granted the authority to survey digesters annually, and EPA renewed that authority until 2025. Learn more about the objectives, history, and previous survey results on the Anaerobic Digestion Data Collection Project homepage.

The data presented below are from the fifth round of data collection, which was completed in 2023. The data are from three types of anaerobic digestion facilities:

Stand-alone food waste digesters.
On-farm digesters that co-digest food waste.
Digesters at water resource recovery facilities that co-digest food waste.

Learn about different types of anaerobic digesters.

Feedstock is another term for the organic material that is “fed” into the digestion process, such as food waste or manure.

The survey of AD facilities completed in 2023 collected the following data for 2020 and 2021:

The amount of food waste processed.
The amount of non-food waste processed.
Feedstock types and sources.
The amount of biogas produced.
Information about tipping fees.

Other data collected reflect circumstances at the time of the survey, including operational dates and operational status, operational specifications, biogas use, and digestate treatment and use. You can access the complete set of survey questions in the Related Links and Resources section of this page.

All data were voluntarily submitted by survey respondents and were aggregated and checked for quality before publication. You can find data from previous years, going back to 2015, in reports on the AD Data Collection Project homepage. EPA maintains a list of AD facilities in the U.S. – those that process food waste and those that do not – that you can download from the Excess Food Opportunities Map.

Survey Responses, Operational Dates, and Status

EPA shared the 2023 survey directly with 310 facilities believed to be operational and for which EPA had contact information. EPA also posted the survey on the AD website. EPA received responses from 51 operational and four non-operational facilities across 22 states. The four non-operational facilities were in the planning, design, or permitting stage, temporarily shut down, or permanently closed. Not all facilities responded to all questions.

Number of Anaerobic Digestion Facilities Processing Food Waste Surveyed in 2023 and Response Rate
Digester Type	Number of Facilities Surveyed in 2023	Number of Submitted Surveys in 2023 (overall)	Number of Submitted Surveys in 2023 (operational facilities)	Survey Response Rate in 2023 (overall)	Survey Response Rate in 2023 (operational facilities)
Stand-alone digesters	92	22	19	24%	21%
On-farm co-digesters	88	6	5	7%	6%
Co-digestion systems at WRRFs	130	26	26	21%	21%
Total	310	55	51	18%	16%

The states with the most operational anaerobic digesters returning survey responses were California (13 responses), Iowa (4), and New York (4). The numbers presented below for food waste processing and biogas production underestimate actual food waste processed and biogas produced in 2020 and 2021 because not all operational AD facilities processing food waste in the U.S. responded to the survey.

The survey asked facilities for their current operational status and the year they began operation. The table below describes in which decade responding facilities came online. Of the 51 survey respondents, the largest number started operations in the 1990s and 2000s.

Food Waste Processing

Of the 51 facilities that were operational at the time of survey, ten did not process food waste in 2020 and 2021. For the purposes of the survey, food waste includes the following categories:

Beverage processing industry waste (e.g., liquid wastes from brewing beer).
Fats, oils and greases (e.g., used cooking oils).
Food processing industry waste.
Food service waste, pre- and post-consumer (e.g., kitchen scraps or uneaten plate waste).
Fruits/vegetative wastes.
Retail food waste (e.g., unsold food from grocery stores).
Slaughterhouse wastes.
Source-separated commercial, institutional or residential organic wastes.
Other food waste.

Where facilities reported their food waste processing amounts in gallons, EPA used conversion factors appropriate for each feedstock to convert gallons to tonnages before calculating the total amount of food waste processed each year. Based on data submitted by 39 survey respondents, and EPA’s conversions where necessary, the total amount of food waste processed in all three digester types in 2020 was over 15.8 million tons. In 2021, 41 respondents processed over 16.8 million tons of food waste.

Beverage processing waste at stand-alone digesters comprised the majority of food waste processed in 2020 and 2021. This is due to several factors. First, beverage processing waste has a density similar to water, whereas source-separated organics, for example, contain less moisture and weigh less. Accordingly, a volume – in gallons – of beverage waste will convert to a greater tonnage than the same volume of source-separated organics. Second, most anaerobic digesters in the U.S. are wet systems, designed to process high-moisture feedstocks, such as process water, wash water, and other liquids that contain organic solids. Finally, over half of the stand-alone facilities responding to the 2023 survey are co-located at breweries and solely dedicated to processing brewery waste. The use of AD systems at breweries is well-established.

The table below describes the amounts of food waste processed in 2020 and 2021 with and without beverage processing waste included, for comparison. Charts below describe food waste processed in 2020 and 2021 on two scales to better illustrate the influence of beverage processing waste on the total annual tonnages. Tonnages are wet U.S. tons.

Total Amount of Food Waste Processed in 2020 and 2021 by Survey Respondents
Digester Type	Reported Amount Processed in 2020 (tons)	Reported Amount Processed in 2020 without beverage processing waste (tons)	Reported Amount Processed in 2021 (tons)	Reported Amount Processed in 2021 without beverage processing waste (tons)
Stand-alone digesters	14,658,403	55,734	15,530,073	189,028
On-farm co-digesters	8,606	8,448	33,729	31,714
Co-digestion systems at WRRFs	1,139,824	1,129,147	1,323,567	1,286,324
Total	15,806,834	1,193,329	16,887,369	1,507,066

In both 2020 and 2021, the top five sources of food waste processed via AD were as follows (in order of most to least tons):

Industrial – manufacturing and processing.
Other – a combination of commercial, residential, institutional and industrial that could not be disaggregated by the facility.
Commercial – restaurants and food services.
Commercial – food retail/wholesale.
Industrial (other).

In 2020 and 2021, the top five types of food waste processed from most to least were as follows (in order of most to least tons):

Beverage processing industry waste.
Food processing industry waste.
Fats, oils and greases.
Other – a combination of beverage processing and food processing wastes.
Source-separated residential, commercial and institutional organics in 2020; Retail food wastes in 2021.

The following charts describe the top five types of food waste processed in 2020 and 2021 on two scales. Access exact amounts, types, and sources of food waste processed in detailed matrix tables on our Supplemental Data webpage.

Top Types of Food Waste Processed in 2020

This is a graph showing the top types of food waste processed by anaerobic digestion in 2020. They include Beverage Processing Industry Waste (15,352,624 tons), Food Processing Industry Waste (832,829 tons), Fats, Oils and Greases (FOG)(382,895 tons), Other (160,000 tons), and Source-Separated Organics (38,739 tons). The majority of beverage processing industry waste was digested at a stand-alone digester. The majority of all other types of food waste were digested in a WRRF digester. On-farm digesters hand

Top Types of Food Waste Processed in 2021

This is a graph showing the top types of food waste processed by anaerobic digestion in 2021. They include Beverage Processing Industry Waste (14,613,505 tons), Food Processing Industry Waste (770,588 tons), Fats, Oils and Greases (FOG)(194,403 tons), Other (160,000 tons), and Retail Food Waste (16,125 tons). The majority of beverage processing industry waste was digested at a stand-alone digester. The majority of all other types of food waste were digested in a WRRF digester. On-farm digesters handled only

Non-Food Feedstock Processing and Available Capacity

Most AD facilities co-digest food waste with other organic waste. Anaerobic digesters at water resource recovery facilities (also known as wastewater treatment plants) are primarily dedicated to digesting wastewater solids (also known as sewage sludge). Anaerobic digesters on farms are primarily dedicated to processing animal manure. Anaerobic digestion decreases the volume of organic materials, which is beneficial for managing large waste streams such as wastewater solids, manure and – increasingly – food waste.

Seven WRRFs reported processing non-food waste feedstocks in addition to wastewater solids generated on-site. Those feedstocks were wastewater solids from other WRRFs, septage, and non-food waste from the industrial sector (e.g., B-grease renderings from making glycerin). Three stand-alone AD facilities reported processing non-food waste feedstocks: wastewater solids and manures.

At the time of survey, 71% of the 28 respondents reported having some available capacity to process feedstocks from off-site sources. The total available capacity at AD facilities is difficult to pinpoint, given that facilities calculate capacity use through a variety of methods. Also, various factors may impact the feasibility for digesters to process additional food waste specifically, such as:

Availability of additional quantities of non-food feedstocks, including manure at on-farm digesters and wastewater solids at WRRFs.
Accessibility of food waste (e.g., proximity to the digester).
Available pre-processing technologies.
Optimal mix of feedstocks for efficient digestion and biogas production.

Tipping Fees

Of 38 respondents, 58% reported collecting tipping fees, which are fees paid to the AD facility by waste haulers or generators to process food waste and other feedstocks. Nine facilities shared data on tipping fees collected in 2020 and 2021. Based on those responses, in 2020 the median tipping fee was $27.63 per ton and the average was $31.82 per ton. In 2021, the median tipping fee was $24.26 per ton and the average was $30.74 per ton. Three facilities reported setting base rates of $0.06, $0.09, and $0.10 per gallon of feedstock. Several facilities charge different rates depending on the quality, type, or source of feedstock. For example, the facility might set fees higher if food waste needs to be de-packaged, they might charge grease haulers but not source-separated food waste haulers, or they may charge to tip food waste but not manure.

Biogas Production and Use

Based on the data reported, the combined total amount of biogas produced from food waste and non-food feedstocks by respondents of all digester types was 14,767 standard cubic feet per minute in 2020 and 22,102 SCFM in 2021. Thirty-three respondents provided data for 2020 and 34 for 2021.

Summary of Biogas Data Reported by Survey Respondents (2020 & 2021)
Digester type	SCFM*	MW	kWh/yr (million)	Equivalent Number of Homes Powered for One Year
All digesters, 2020	14,767	46	342	28,170
All digesters, 2021	22,102	69	512	42,163

*Facility operators reported values in SCFM, SCFD or SCFY, which were converted to SCFM by EPA, and summed to get annual totals. Equivalencies in MW, kWh/yr and number of homes powered were calculated using the Landfill Methane Outreach Program interactive conversion tool.

Facilities often scrub biogas to remove unwanted components before they use it. Of 38 responding facilities, 79% reported using a gas cleaning system at the time of survey. The most common constituents removed were hydrogen sulfide, sulfur, and moisture.

Facilities use biogas to produce heat and electricity or convert it into renewable natural gas. Facilities can use biogas and the resulting energy onsite, sell energy to the grid or pump upgraded biogas into a pipeline. Only two out of 38 respondents reported selling all the biogas they produced and not using any onsite. The most common use of biogas for WRRFs and farms at the time of survey was to produce both heat and electricity through combined heat and power systems. The second-most common use for WRRFs was as fuel for boilers and furnaces to heat the digesters. For stand-alone facilities, the most common use of biogas was as fuel for boilers and furnaces to heat other spaces (i.e., not the digesters). The second-most common use for stand-alone facilities was to produce electricity for sale to the grid.

When a facility cannot use or sell all the biogas it produces, they flare the excess biogas, which is a common practice. Thirty-three out of 38, or 87% of respondents reported flaring some or all the biogas they produced. Three facilities reported only flaring biogas and not putting any to use onsite or offsite.

Operational Specifications and Pre-processing Activities

As in previous surveys, results show that most digesters are wet and mesophilic systems (34 out of 38). For WRRFs and stand-alone facilities at the time of survey, the most common pre-processing activity was screening or sorting. Six facilities (two WRRFs, three stand-alone and one farm) reported doing manual or mechanized de-packaging.

Digestate Uses

Digestate is often, but not always, separated into liquid and solid portions, which are then treated and managed separately.

The top uses of solid digestate by digester type in the 2023 survey were:

Stand-Alone Digesters: composted into a reusable or salable product, and de-watered or dried then land applied. Other reported uses include turning digestate into animal bedding or cattle feed or selling digestate to help start up other digesters.
On-Farm Co-Digesters: processed into animal bedding (single response).
Co-Digestion Facilities at WRRFs: de-watered then land applied and landfilled. Other reported uses include land applying as-is with no dewatering and composting into a reusable or salable product.

The top uses of liquid digestate by digester type in the 2023 survey were:

Stand-Alone Digesters: discharged to a wastewater treatment plant and reused as fertilizer via land application.
On-Farm Co-Digesters: reused as fertilizer via land application.
Co-Digestion Facilities at WRRFs: discharged to a wastewater treatment plant (i.e., returned to the beginning of the wastewater treatment system) and recirculated through the digester.

Annual Survey Results

The table below provides a brief snapshot of the annual results for amounts of food waste processed and biogas produced as well as survey response rates since the start of EPA’s AD Data Collection Project.

Critical Data Points Reported by Survey Respondents for Years 2015 - 2021
Data Year	Food-Based Feedstock Processed (tons)	Number of Digesters Providing Feedstock Data	Biogas Produced (SCFM)	Number of Digesters Providing Biogas Data	Survey Year	Number of Facilities Surveyed	Survey Response Rate (operational facilities only)
2015	11,341,813	137	34,967	122	2017	154	89%
2016	10,691,756	131	40,304	119	2018	198	68%
2017	9,633,373	110	25,274	103	2019	209	56%
2018	9,814,871	111	27,193	105	2019	209	56%
2019	17,598,063*	73	29,877	87	2021	275	36%
2020	15,806,834*	39	14,767	33	2023	310	16%
2021	16,887,369*	41	22,102	34	2023	310	16%

*2019 was the first year for which the granularity of data collected allowed specific densities to be assigned to specific feedstocks. For example, beverage processing industry waste was assigned the density of water (8.34 lb/gallon), higher than the density of source-separated organics and other similar food wastes (3.8 lb/gallon).

The number of identified AD facilities processing food waste in the U.S. has increased steadily since the beginning of the AD Data Collection Project, from 154 in 2017 to 310 in 2023 (and 310 is likely an undercount). Conversely, the survey response rate has decreased steadily. Each year, the specific facilities that report and the number of facilities that respond to each survey question varies. So, it is not recommended to analyze year-over-year trends in these data.

The AD industry has seen dramatic growth since 2015. When properly permitted and operated, AD projects can provide economic, health, and environmental co-benefits to surrounding communities while recovering energy and nutrients from organic materials. However, there are challenges with anaerobic digestion, as with any food waste management technology, and EPA encourages communities to consider lifecycle and other environmental impacts when deciding how to manage wasted food and other organic materials.