Anaerobic Digestion Explained
An innovative process that helps turn organic
waste into a cleaner natural gas alternative
What is anaerobic digestion?
A variety of biomass material, or organic waste, can be transformed into biogas through the biological process of anaerobic digestion.
Anaerobic digestion is a process in which bacteria break down organic matter —such as animal manure, wastewater biosolids, and food waste— without oxygen. It can occur in several settings, including landfills and the covered lagoon systems used by some livestock operations. Both can be equipped to capture the gases generated through naturally occurring anaerobic digestion.
Another setting is a sealed vessel called a bioreactor, which comes in various shapes and sizes tailored to specific site conditions and waste types. Inside the reactor, microbial communities digest the waste into two outputs:
• biogas – which consists of a mixture of various gases and water vapor, and which can be upgraded and used as a renewable energy source, and
• digestate – the material remaining after anaerobic digestion, which separates into solid and liquid fractions and can be used as fertilizer or soil conditioner.
The Process of Anaerobic Digestion
From biogas to biofuel
After biogas is collected from the bioreactor, it must be purified before it can be used as a replacement for natural gas. In this process, COâ‚‚, hydrogen sulfide, water and other impurities are taken through the application of specialized membrane and technology, including carbon scrubbers.*
The resulting methane-rich, pipeline quality renewable natural gas (RNG) is prepared for its specific use, whether that be for vehicle fuel, or to power and heat homes and businesses.
Turning food waste into RNG offers a variety of environmental benefits
Instead of letting organic waste decompose in landfills, where it releases methane into the atmosphere, anaerobic digestion harnesses that energy for practical use. Methane (CH₄) is a potent greenhouse gas and the second‑largest contributor to Earth’s warming after carbon dioxide (CO₂)*, so capturing and utilizing it is environmentally important.
While landfills attempt to capture and burn methane through a process called flaring, this approach wastes potential energy and contributes to further greenhouse gas emissions. Even when methane is converted into renewable natural gas (RNG), some portion may still be flared if it is out of specification, meaning greenhouse gas emissions can continue.*
* Source: Nasa.gov and EPA.gov
Environmental benefits of producing RNG from food waste
Reduces greenhouse
gas emissions
- Can help avoid methane emmissions into the atmosphere that occur at landfills
- May be used to displace conventional fuels in existing infrastructure
- Can potentially be produced and consumed locally
Alleviates issues
of overtaxed landfills
- Can divert some waste destined for a landfill
- May reduce the potential for harmful leachate to leak from the landfill
- Can support compliance with relevant state and local food waste regulations
Supports sustainable
food production
- Can produce digestate, a nutrient‑rich by‑product used as fertilizer to support sustainable food production
Anaerobic digestion captures methane from organic waste, so it can be purified and injected directly into natural gas pipelines. This transforms a once-wasted byproduct into a valuable energy source that can be used for heating homes, cooking, and other everyday needs, potentially reducing the use of more carbon-intensive fuels.
Striving to Reduce
CO2 Emissions
The Linden Renewable Energy (LRE) project will be a resource located in NJ that is designed to help avoid methane emissions through the diversion of organic waste from landfills. Methane is a potent greenhouse gas. According to the US EPA, methane is more than 28 times as potent as COâ‚‚ at trapping heat in the atmosphere.* The LRE project will use the diverted organic waste to produce RNG, which will be injected into the Elizabethtown Gas pipeline system, displacing fossil natural gas.
Turning Food Waste from
Homes into Energy for Homes
Turning local food waste into renewable energy through anaerobic digestion diverts valuable resources from going to landfills and helps to avoid methane emissions, all while providing a cleaner fuel to work towards creating a more sustainable future. Â Processing 100 tons of food waste daily via anaerobic digestion can generate enough energy to power 800 to 1,400 homes every year.*
Turning Food Waste from
Homes into Energy for Homes
Turning local food waste into renewable energy through anaerobic digestion diverts valuable resources from going to landfills and helps to avoid methane emissions, all while providing a cleaner fuel to work towards creating a more sustainable future. Â Processing 100 tons of food waste daily via anaerobic digestion can generate enough energy to power 800 to 1,400 homes every year.*
SJI Renewable Energy Ventures and its affiliates are turning today’s organic waste into pipeline-quality gas.
Learn how we can help your business move to a more sustainable future.