Food Waste to Energy Initiative
We are currently working towards a Food Waste to Energy initiative to create renewable natural gas to fuel Mesa's solid waste fleet. Food waste emits a significant amount of methane from the landfill. Our project aims to divert food waste for a beneficial use.
Project Phases
Feasibility Study – Complete
We completed a feasibility study in 2020 to evaluate the technical, financial, and operational feasibility of adding commercial food waste into a wastewater reclamation plant that has extra treatment capacity. The big domes you see when you drive by the wastewater reclamation plant near the 101 and 202 interchange are called anaerobic digesters, and they break down sewer waste and create natural gas as a byproduct. Food waste added to the digesters helps create more gas that we then filter into clean, renewable natural gas (RNG). The RNG can be used to fuel Mesa’s trash trucks.
As part of the study, we partnered with many local organizations to collect and process all types of food waste. Then, the Arizona State University Biodesign Swette Center for Environmental Biotechnology lab used the processed food waste and sewer waste from the plant in small, imitation anaerobic digesters to help study what the project could look like at full scale.
The study provided valuable information on collection of food waste, operational needs, potential issues to be aware of, and project benefits. The key takeaway from the study was that the project is feasible, and we will move forward to the next phases.
Phase 1: Flare to Fuel Plant Biogas Upgrade – Estimated Completion Early 2025
The first phase of the project is to design and install the equipment and infrastructure to filter the gas from existing plant operations, create RNG, inject the RNG into Mesa’s natural gas utility, and use it to fuel some of our trash trucks. Essentially, we are capturing the gas waste that is released (flared) during plant operations and creating a renewable energy source.
This phase of the project does not directly include food waste, but all equipment installed is sized for the next phase which does include collecting and processing food waste.
Phase 2: Food Waste to Energy
The next phase of the project is to design and build a food waste pre-processing facility where trash trucks can dump collected food waste and it gets processed into a bioslurry. Generally processing involves removing contamination, grinding up the food waste, and adding water as needed. The facility will also conduct sampling to ensure it is safe to send it to the water reclamation plant.
Lastly, the project includes the design and building of an offloading tank and injection system into the anaerobic digesters at the plant.
A final component will require our Solid Waste Department to identify community partners who want to participate and develop a food waste collection program.
Frequently Asked Questions
What are the benefits of the project?
- Supports all aspirational goals in Mesa’s Climate Action Plan which includes carbon neutrality, renewable energy, waste diversion, and climate-ready community
- Saves greenhouse gas emissions by reducing the flaring of gas and using it as a resource
- Replaces the need for conventional fuel sources and offsets the purchase of fuel for our vehicles
- Extends the life of the landfill by diverting waste and using it as a resource
- Helps community partners reach their own food waste diversion goals
- Builds a more resilient, local supply of renewable natural gas
- Supports the national initiative to reduce greenhouse gas emissions and expand the nation’s renewable fuels sector while reducing reliance on imported oil by participating in the EPA Renewable Fuel Standard.
Why do we use food waste to make renewable fuel?
According to the U.S Environmental Protection Agency, in the United States, food is the single largest category of material placed in municipal landfills, where it emits methane, a powerful greenhouse gas.
Preventing food waste is the most important action the community can take to sustainably manage food systems. Our project is the last pathway for preventing or managing wasted food. Our project will utilize food waste that is discarded and not able to be consumed by humans or animals, spoiled food, or peels and rinds considered inedible.
EPAs Wasted Food Scale
What is the best way to manage food waste?
Landfilling food waste can emit significant amounts of methane, a greenhouse gas that contributes to climate change. Anerobic digestion of food waste releases less methane to the environment.
Metric Tons (MT) of methane emitted per million metric tons (MMT) of organic waste managed by landfilling, composting or anaerobic digestion.
| Metric Tons of Methane Released per MMT of Food Waste |
| Landfilling |
Composting |
Anaerobic Digestion |
| 26,000 |
2,800 |
1,600 |
Will Mesa accept food waste from residents and businesses?
As noted above, our Solid Waste Department will establish contracts with commercial partners for food waste collection. We will not be accepting food waste from residents or businesses that do not have agreements with our Solid Waste Department. For more information or inquiries, please reach out to waste.info@mesaaz.gov.
What partners has Mesa worked with on this project?
As part of the feasibility study, Mesa partnered with many organizations including Arizona State University, Arcadis, and their subconsultants. We collected food waste from United Food Bank, Mesa Public Schools, Sheraton Hotels, East Valley Institute of Technology Culinary School, and Bashas. We also partnered with City of Tempe’s Grease Cooperative to sample fats, oils and greases. We also received a grant from Arizona Recycling Coalition (now Circular Arizona) for sampling equipment.
Many departments in Mesa are supporting this effort including Water Resources, Solid Waste, Energy Resources, Engineering, and Environmental & Sustainability.