Call or Text Now 
The U.S. biogas industry has huge potential for growth, with over 17,000 sites ready for development that could generate 194 billion kilowatt-hours of electricity annually and cut emissions equal to removing 2.6 million cars off the road.
In other words, biogas digesters create a powerful opportunity to turn everyday waste into a renewable energy source.
From small biogas systems to large-scale projects like the Linden Renewable Energy Project, this approach supports zero-waste goals, energy needs, methane reduction, and more—and food waste to energy companies are driving this change.
Keep reading to learn more about the biogas digester process, common feedstocks, the benefits of producing biogas from waste food, and more.
Key Takeaways
- A biogas digester is an airtight enclosed container where microorganisms produce biogas from food waste.
- Common types of feedstocks for biogas production include food waste, manure, crop residues, wastewater sludge, and fats, oils, and grease.
- Co-digestion, which involves digesting multiple types of organic material simultaneously, is used to increase methane production from low-yielding or difficult-to-digest feedstocks.
- Biogas can be used in various applications, including electricity generation, heating, and fueling renewable natural gas (RNG) pipelines or vehicles.
- From reducing landfill use to minimizing food waste hazards and decreasing reliance on fossil fuels, biogas digesters play a vital role in creating a more sustainable, circular economy.
What Are Biogas Digesters and How Do They Work?
A biogas digester is an airtight enclosed container where microorganisms produce biogas from food waste.
These systems are structured to optimize the decomposition of organic material, and while they come in different types, they all follow a clear process of converting waste through multiple stages to generate renewable energy.
What is anaerobic digestion?
As defined by the American Biogas Council, anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in the absence of oxygen. This process produces biogas, a renewable energy source made from methane and carbon dioxide, and digestate, a nutrient-rich material that can be used as fertilizer.
The 4 Stages of Biogas Digestion
Understanding how anaerobic digestion works is key to getting a clear overview of how biogas systems turn waste into energy.
So that brings us to our next question: how do biogas digesters work?
This process can be broken down into 4 stages:
- Hydrolysis: In the first stage of anaerobic digestion, complex organic materials—such as carbohydrates, proteins, and lipids in food waste—are broken down into simpler compounds like sugars, amino acids, and fatty acids.
- Acidogenesis: Next, fermentative bacteria convert the simple compounds produced in the previous stage into volatile fatty acids (VFAs), alcohols, carbon dioxide, hydrogen, and other by-products.
- Acetogenesis: Acetogenic bacteria then further break down the VFAs and other products generated during acidogenesis into acetic acid, hydrogen, and carbon dioxide.
- Methanogenesis: And lastly, microorganisms called methanogenic archaea convert the acetic acid, hydrogen, and carbon dioxide generated in the previous stages into methane and carbon dioxide.
Types of Biogas Digesters
There are different biogas digester types designed to suit your feedstock, climate, and energy goals.
So what are the different types of biogas digesters?
Here’s what you should know:
- Plug-flow: ScienceDirect describes plug-flow digesters as unmixed systems that operate semi-continuously by regularly receiving new, untreated “plugs” of manure while pushing digested waste out the opposite end of the digester. Since these systems can tolerate a broader range of solids concentrations, they can be used at a wider variety of operations.
- Covered lagoons: A covered lagoon digester is a large anaerobic lagoon with a long retention time and a high dilution factor. In areas with consistently high temperatures, digesters are able to produce nutrient-rich, low-odor effluent for fields and crops, reduce pathogen levels and weed seeds, and generate biogas to meet farm energy needs.
- Dry digesters: A dry digester generally processes feedstock with greater than 15% solids content. Dry anaerobic digestion is suitable for high-solid wastes like food and agricultural waste.
- Batch vs. continuous systems: A batch process involves putting nutrients in the waste digester at the start and not adding any more for the remainder of the cycle—resulting in a quick and easy-to-manage process. Continuous systems, on the other hand, have a constant flow of feedstock, meaning they are emptied and filled regularly to maximize production.
- Mesophilic vs. thermophilic systems: In mesophilic digestion, the temperature ranges from 95–100°F, providing a more stable operation but a lower biogas production rate. Thermophilic systems operate at higher temperatures—between 122°F and 149°F—resulting in faster reaction rates and increased pathogen destruction.
What Can You Feed a Biogas Digester?
Feedstocks are the materials fed into anaerobic biogas digesters. Since these materials determine the quality of the biogas that comes out, it’s important to understand the different sources of biogas.
1. Common Feedstocks
Common types of feedstocks for the production of biogas include:
- Food waste: Food waste is a highly desirable substrate for anaerobic digesters because of its high biodegradability and methane yield. In addition, food waste biogas digesters help reduce the environmental, economic, and social consequences of organic waste, making it a valuable approach to enhancing sustainability.
- Manure: While manure is among the lowest methane-yielding feedstocks in digesters, the anaerobic digestion of manure is widely used in agricultural settings due to its continuous availability, capacity to resist changes in pH, and relatively easy integration into existing manure management systems.
- Crop residues: Crop residues—such as bruised or undersized fruits and vegetables, or parts of produce that are removed like leaves and roots—can also be used to produce biogas. This feedstock not only generates renewable energy but also helps farmers manage agricultural waste sustainably and reduce greenhouse gas emissions.
- Wastewater sludge: Did you know that wastewater sludge could be used as feedstock? Sewage sludge-to-energy conversion is a sustainable waste management technique that helps mitigate the environmental concerns associated with its disposal.
- Fats, oils, and grease: Fats, oils, and grease is a waste stream that has the potential to increase biogas production in anaerobic digestion. Because they are highly energy-dense, even small amounts can significantly boost methane yield.
Choosing the right feedstock is crucial, as it affects operational costs and the quality of the end product. For instance, agricultural waste, organic waste, energy crops, and industrial byproducts are all common feedstocks for biofuel, each with unique characteristics like energy content, yield, and growth rate.
2. Co-Digestion Benefits
Co-digestion happens when more than one type of organic material is digested at the same time.
This process is used to increase methane production from low-yielding or difficult-to-digest feedstocks. For co-digestion to be successful and maximize methane production, compatible feedstocks must be carefully selected. Existing biogas digesters must also be able to handle the significant increase in methane output.
That said, co-digestion is a great solution for commercial food disposal, as it allows businesses to divert large volumes of organic waste from landfills while producing renewable energy and nutrient-rich fertilizer.
Science Direct states, “Significant research and development efforts have highlighted several inherent merits of co-digestion, including enhanced digestibility due to synergistic effects of co-substrates, better process stability, and higher nutrient value of the produced co-digestate.”
What You Get Out: Biogas & Digestate Benefits
Anaerobic digestion has two outputs: biogas and digestate. Companies like Shapiro will partner with you to produce valuable products made from food waste, but to better understand what this means, let’s take a look at these two outputs.
1. Energy Output (Biogas)
Biogas is a mixture of approximately 60% methane, 39% carbon dioxide, and 1% water vapor, hydrogen sulfide, and some other gases by volume.
While methane is a powerful greenhouse gas, the benefit of producing it in anaerobic digester systems is that it’s captured and contained, meaning it has less of an impact on the environment.
But what is biogas used for?
Biogas can be used in various applications, including electricity generation, heating, and fueling renewable natural gas (RNG) pipelines or vehicles. By converting food waste into electricity, biogas systems help reduce landfill use, lower greenhouse gas emissions, create renewable energy, and support a more sustainable circular economy.
By powering RNG solutions, biogas also helps replace fossil fuels in transportation and heating, further reducing carbon emissions and enhancing energy security.
2. Byproduct: Digestate
Digestate is the material left after anaerobic digestion. It’s characterized by its nutrient-rich composition, which includes a balanced mixture of macro- and micronutrients essential for plant growth.
By using digestate to improve soil health, it closes the loop of resource recovery, returning valuable nutrients to the land and supporting sustainable agriculture.
There are also economic benefits to using digestate, such as reducing the need for chemical fertilizers, improving soil health to increase crop yields, and generating income through compost sales or soil amendment products.
Why Biogas Digesters Are Key to Zero-Waste Energy
Biogas digesters are key infrastructure in the clean energy transition. From reducing landfill use to minimizing food waste hazards and decreasing reliance on fossil fuels, these systems play a vital role in creating a more sustainable, circular economy.
1. Reducing Methane Emissions
Reducing methane emissions offers benefits for human health, food security, and ecosystems, making it one of the most valuable outcomes of biogas production.
In the U.S., surplus food is responsible for almost four million metric tons of methane—nearly 14% of the country’s total methane emissions and the equivalent to what’s generated by 75 million cars annually. Establishing organics diversion infrastructure, addressing consumer food waste, and incentivizing business prevention solutions could together cut U.S. methane emissions by almost 6%.
That said, the adoption of biogas digesters plays a vital role in meeting global climate targets and supporting circular economy initiatives that turn waste into renewable energy and valuable resources.
2. Biogas vs. Fossil Fuels
Biogas is a renewable, clean-burning alternative. As explained by the Environmental and Energy Study Institute, “After biogas is captured, it can produce heat and electricity for use in engines, microturbines, and fuel cells. Biogas can also be upgraded into biomethane, also called renewable natural gas or RNG, and injected into natural gas pipelines or used as a vehicle fuel.”
The advantages of biogas over fossil fuels are clear: Fossil fuels are non-renewable energy sources that include coal, natural gas, derived gas, crude oil, and more. Unlike fossil fuels, which release new carbon into the atmosphere, biogas uses existing organic waste, offering a renewable energy solution that supports emissions reduction and advances a more sustainable energy system.
3. Policy & Market Demand
Federal and state policies are increasingly supportive of RNG production. Incentives like the Renewable Fuel Standard and California’s Low Carbon Fuel Standard encourage biogas development and create strong momentum for scaling up RNG infrastructure nationwide.
At the same time, demand from energy buyers and municipalities is rising as organizations look to meet climate goals and secure low-carbon energy supplies. In this evolving landscape, projects like the Linden Renewable Energy Project are well-positioned to deliver reliable RNG solutions that align with policy priorities and market needs.
How Shapiro Supports Your Biogas Digester Strategy
While our team does not operate digesters for biogas, we facilitate the entire process by connecting businesses with trusted waste treatment facilities. We accomplish this by collecting food waste and managing feedstock sourcing, compliance, and logistics—everything you need to increase sustainability while reducing the hassle.
Our partnership with the Linden Renewable Energy Project further expands this capability. Once completed, this anaerobic digestion facility is set to be the nation’s largest food waste-to-biogas facility, and our team at Shapiro is part of a network of industry leaders contributing feedstock to this project.
Whether you’re interested in our work with the Linden Renewable Energy Project or want to explore other waste management solutions, we specialize in helping companies meet local food waste recycling laws and ESG goals through smarter sustainable organic solutions.
Conclusion
Biogas digesters turn food and organic waste into clean, usable energy. With this approach, companies can reduce waste, generate energy, and stay compliant—all while supporting sustainability.
At Shapiro, we’re strong supporters of anaerobic digestion (among other waste management solutions). We’ll work closely with you to create a tailored solution that meets the unique needs of your business—without disrupting your day-to-day operations.
Contact us today to learn more about our services.
Baily Ramsey, an accomplished marketing specialist, brings a unique blend of anthropological insight and marketing finesse to the digital landscape. Specializing in educational content creation, she creates content for various industries, with a particular interest in environmental initiatives.
