PCR Credit: Anaerobic Digestion Infrastructure 

(1-2 points Reciprocal) 

Credit Summary  

The PCR Credit: Anaerobic Digester Infrastructure credit intends to develop infrastructure to provide optimized anaerobic breakdown of food waste and, if indicated, other organic material to produce gas, Digestate and other useful products. To achieve this credit, local governments and industries must demonstrate the Anaerobic Digestion of adequate food waste generated or demonstrate the capacity to do so. In addition, 80% of the output gas must be used by the facility. 

Impact Summary

Anaerobic Digestion is a naturally occurring process through which organic matter breaks down in the absence of oxygen and produces methane biogas, which can then be used for energy. This process has substantial environmental and economic benefits. 

Submittal Summary

To meet the credit’s requirements, one’s facility must create the capacity to anaerobically process food waste, include gas scrubbing and/or other process equipment, and utilize a wastewater treatment plant. One must utilize SWEEP calculators and submit their results to demonstrate that they met these requirements. 

Case Studies and Benefits

The vast benefits of Anaerobic Digestion infrastructure can be seen through a case study of Atlas Disposal Industries. Atlas is a waste management and recycling facility that decided to produce green energy from the Anaerobic Digestion of food waste. Benefits of this transition include a constant supply of clean energy for trucks, reduced waste hauling costs, as well as the use of a cleaner fuel with a 16% reduction in greenhouse gas emissions. 

Other Resources

Additional resources, such as referenced standards and relevant definitions are available.

SUPPORTING MATERIALS 

Intent and Requirements

Intent

To develop infrastructure to provide optimized anaerobic breakdown of food waste and, if indicated, other organic material to produce gas, digestate and other useful products.

Local Government & Industry Requirements

SMMP Performance Path

Tier 1: (1 point)

Demonstrate food waste reduction of at least 5% or CO2e reduction equivalent to 5% of food waste generated being anaerobically digested.

Tier 2: (+1 point)

Demonstrate food waste reduction of at least 15% or CO2e reduction equivalent to 15% of food waste generated being anaerobically digested.

SMMP Prescriptive Path

Tier 1: (1 point)

Demonstrate operating capacity (centralized and/or distributed) to anaerobically digest 15 percent of the food waste generated. Demonstrate that 5 percent of food waste generated is being anaerobically digested.

Tier 2: (+1 point)

Demonstrate operating capacity (centralized and/or distributed) to anaerobically digest 25 percent of the food waste generated. Demonstrate that 15 percent of food waste generated is being anaerobically digested.

In all cases, demonstrate biogas processing and utilization infrastructure to utilize a minimum of 80% gas output of the facility.

The Big Picture

Why We Care

Anaerobic Digestion is a naturally occurring process through which organic matter breaks down in the absence of oxygen and produces methane biogas, which can then be used for energy. Environmentally, this process: 

• Displaces fossil fuel energy consumption through biofuel usage, contributing to climate change mitigation
• Reduces pathogens, benefiting human and animal health 
• Lessens the amount of food waste sent to landfills, as restaurants and grocery stores are able to send their waste for digestion 

Economically, there are benefits as well. These include: 

• Reduced energy costs, as energy is produced on-site
• The collection of tipping fees for accepting food waste from food processing companies
• Increased job opportunities for local contractors, skilled laborers, businesses specializing in nutrients and energy, and agro-tourism 1  

How to Meet the Requirements 

To obtain the PCR credit “Anaerobic Digester Infrastructure,” one must: 

• Create capacity to process the required volume of food waste using Mesophilic or Thermophilic Anaerobic Digestion equipment.

OR

• Include gas scrubbing and other processing equipment, such as compressors for use as transportation fuel or direct connection with combined heat and power generators or connection with existing gas transmission networks.

OR

• Utilization of wastewater treatment plant and/or farm-based infrastructure for Anaerobic Digestion.

Required Documentation 

Must follow either the SMMP Performance Path or the SMMP Prescriptive Path. 

SMMP Performance Path 

Tier 1: 

Tons of food waste digested ÷ Tons food waste generated 

Tier 2: 

Tons of food waste digested ÷ Tons food waste generated 

SMMP Prescriptive Path 

Tier 1: 

• Tons food waste digestion capacity ÷ Tons of food waste generated
• Tons of food waste digested ÷ Tons food waste generated

Tier 2: 

• Tons food waste digestion capacity ÷ Tons of food waste generated
• Tons of food waste digested ÷ Tons food waste generated 

Case Studies & In-Depth Information 

Atlas Disposal Industries is a Waste Management and Recycling Facility in Sacramento, California that, in 2011, decided they wanted to take a step towards increasing their sustainability. Along with the South Area Transfer Station (SATS), Atlas decided they wanted to “produce green energy and/or fuel from residential and/or commercial solid waste or from organic wastes such as green waste or food waste” through Anaerobic Digestion. They partnered with CleanWorld — a technology startup with access to developing, operating, and maintaining anaerobic digesters — to do this. Through this infrastructure that enabled the Anaerobic Digestion of organic waste, renewable compressed natural gas (r-CNG) was used to fuel Atlas’ heavy-duty refuse trucks and other natural gas vehicles in Sacramento. 

Atlas was an ideal company to make this transition towards anaerobically digesting their waste, as their clients included local restaurants that sorted out their food waste. This constant, secure, access to organic waste feedstocks is critical to the success of an Anaerobic Digestion project and made Atlas’ transition much easier and a natural progression. 

There were many financial benefits for Atlas as a result of their transition to using anaerobically digested gas and their partnership with CleanWorld. Atlas’ access to a fixed-price vehicle fuel (r-CNG) from their anaerobic digester balances out the greater cost of CNG trucks, ultimately saving them money. In addition, ownership of the fueling station has allowed Atlas Refuel to recruit additional CNG fleet customers, which produces more fuel-sales revenue. Finally, their close proximity to the digester reduces their waste hauling/transport costs compared to landfilling. 

There were also various health, environmental, energy security, and climate benefits for Atlas. The switch to using CNG resulted in the use of a cleaner, commercially viable transportation fuel that emits far fewer air pollutants (particulate matter, nitrous oxides, sulfur oxides, carbon monoxide, etc.) with links to negative health and environmental effects. Furthermore, this change resulted in a 16% reduction in greenhouse gas emissions, compared to the conventional diesel. Federal and state incentives were also given to encourage the use of renewable fuel used and developed, with technical and financial assistance given as needed.2 

ADDITIONAL RESOURCES 

Referenced Standards 

N/a 

Definitions 

Anaerobic Digestion

EPA Definition: Anaerobic digestion is a process through which bacteria break down organic matter—such as manure—without oxygen. As the bacteria “work,” they generate biogas. The biogas that is generated is made mostly of methane, the primary component of natural gas.

SWANA Definition: Degradation of organic wastes in the absence of oxygen by microorganisms and bacteria, releasing methane that can be collected and used as a fuel and producing relatively inert solid materials that can be processed for use as a soil amendment. An example of Anaerobic Digestion is the waste degradation that occurs in a landfill.

CO2e

EPA definition: Carbon dioxide equivalent or CO2e means the number of metric tons of CO2 emissions with the same global warming potential as one metric ton of another greenhouse gas 

Digestate

EPA Definition: The material that is left after anaerobic digestion happens is called “digestate.” Digestate is a wet mixture that is usually separated into a solid and a liquid. Digestate is rich in nutrients and can be used as fertilizer for crops.

Mesophilic Anaerobic Digestion 

Wikipedia Definition: Mesophilic digestion takes place optimally around 30 to 38 °C, or at ambient temperatures between 20 and 45 °C, where mesophiles are the primary microorganisms present.

Thermophilic Anaerobic Digestion 

Wikipedia Definition: Thermophilic digestion takes place optimally around 49 to 57 °C, or at elevated temperatures up to 70 °C, where thermophiles are the primary microorganisms present.