Today’s public works directors and other county officials are realizing a lot of waste does not need to be landfilled. It can be used to create renewable energy. And it is easier than you think.
By Shayne Petkiewicz
For some in county management, it is about the ethics of continuing to bury so much of what people throw away. Others are running out of landfill space and do not want—or cannot afford—to open another. Some want to go beyond what their predecessors have done. For some, it is all of these reasons, plus a myriad of unique local factors.
Whatever the reasons, public works directors, utilities directors and landfill directors are looking for ways to divert more waste and landfill less. Most in the industry are aware of the stats: total MSW generation in the U.S. has increased by 232 percent since 1960, mainly due to population growth.1 Most county leaders understand that a great deal of MSW is food waste. What many do not realize is that methane emissions from landfills are getting more attention as major contributors to the climate crisis. More than 43 percent of what gets landfilled in the U.S. is material that creates fugitive methane—food, yard clippings or paper/cardboard2, and consequently, U.S. landfills produce at least 888 billion cubic feet of methane every year.3 That is enough methane to provide power for over six million homes.
Methane emissions from landfills are proving to be a larger problem than those from oil and gas operations, findings indicated using enhanced measurement tools like aerial or satellite monitoring. For example, in California, satellite readings indicate landfills are the number one source of methane emissions (41 percent)—more than the state’s significant oil and gas operations.4 Conversely, if that methane were eliminated by diverting organic waste from U.S. landfills, it would have the effect of eliminating more than 695 million tons of CO2e/year (based on a 20-year time horizon), which is more than 13 percent of total annual U.S. carbon dioxide emissions.5
Addressing Tough Challenges
While these issues can seem intractable, today’s technologies can do a lot to solve both the problem of space constraints as well as the methane emissions challenge. Food scraps and yard clippings contain a lot of water, and in the range of the stuff people put in their waste bins, they are among the heaviest. Surprisingly, when these materials are extracted from MSW, the amount of waste landfilled can be reduced by 30 percent.
When diverted from landfills, that waste can be put to good use through anaerobic digestion—a process that creates renewable biomethane from organic material. That way, this waste fraction both reduces methane created in the landfill—and can be used to replace fossil fuels.
That is exactly what is happening in the greater Los Angeles, CA, area, where food waste diversion became a state mandate in January 2022. WM, a waste disposal and recycling company, took a leading role and implemented an organics recovery system at their Sun Valley Recycling Park in in Sun Valley, California in 2020.6 There, food and other organics are extracted using organics extrusion technology, consistently pulling organic material—about 30 percent of the weight of the total MSW. This organic material is then converted to carbon-negative renewable energy and a nutrient rich soil amendment at the Rialto Bioenergy Facility, one of the largest anaerobic digestion facilities in North America located in nearby Rialto, CA.7
How it Works
The system WM uses was created by global renewable fuel producer, Anaergia8 and can recover about 90 percent of putrescible organics from solid waste. Here’s how it works: First, shredders pull apart the waste and prepare for downstream processing. Then, a disc screen separates out larger dry material from smaller wet material. Once metals are removed using magnets, the OREX™ organics extrusion machinery goes to work, using high pressure to squeeze out the food and other organics from the remaining material. Finally, the recovered wet organics are moved to a load-out bin and transferred to a truck to be taken to the anaerobic digestion facility.
Remarkably, this system and extrusion technology eliminates the need for consumers to source separate their food waste.9 Most residents are notoriously bad at figuring out which bin their food and other organic waste should go in, and they often do not bother to try—with lots of food waste going into the landfill as a result. An organics extraction system solves this problem by recovering organics from the trash bin and is even more economical than source separation. Waste haulers can eliminate separate collection bins and additional pickup routes, saving considerable labor and fuel costs.
Advantages do not stop there. Once the organics are separated, they are then anaerobically digested10 to create biogas, a renewable fuel that either can be used to generate renewable power or upgraded to renewable natural gas. This renewable natural gas can then be injected into the natural gas grid to fuel vehicles or heat homes, while also generating renewable fuel credits that expand its value.
The biogas created from food and other organic waste is considered carbon-negative, meaning that throughout its lifecycle, it takes more carbon out of the atmosphere than it emits when combusted. This is because it significantly reduces fugitive methane emissions from landfills and the resulting climate impact.
In other words, extracting food and other organic waste from MSW creates a circular economy, where waste is used to create energy and soil amendments. A circular economy is exactly what Kent County, MI, has in mind as it implements its forward-thinking approach in plans for a Sustainable Business Park.11 This facility is designed to help the county reach its bold goal to divert 90 percent of county-generated trash that goes to landfills by 2030.
Where Organics Diversion Can Be Implemented
While Kent County, MI’s plans12 are exceptionally ambitious, any county that owns its landfill can implement an organics recovery system like WM’s in Sun Valley, CA.
The system can be integrated into existing materials recovery facilities or transfer stations. Space requirements for organics extraction range from about 10,000 to 40,000 square feet. Anaerobic digestion systems’ space requirements vary, but the Rialto Bioenergy Facility, for example, which is capable of processing 1,000 tons per day, uses only 5.5 acres. If a county’s wastewater treatment plant includes anaerobic digestion, the extracted organics can be digested there to avoid enlarging the municipality’s public works footprint.
County leadership looking to create an organics diversion facility should consider a company that can serve as a complete delivery partner rather than simply a supplier. Full-service companies can offer not only feasibility studies, design, development, and construction, but also financing—saving municipalities the risk and work involved in obtaining their own funding.
For insight into the process, here are the steps a partner company would take to implement an organics separation and renewable energy production project for a municipality:
1. The partnership would typically begin with an initial feasibility study—a high-level overview to determine the best turnkey solution for the particular municipality. Conditions and variables such as total tons of waste, waste characterization, landfill location, and space availability or constraints are evaluated at this stage.
2. If this initial feasibility review indicated a project would be viable, the partner would enter a design and development phase where details of the facility, engineering and permitting would be established.
3. Step 2 allows for a detailed economic assessment followed by project-specific financing that can be obtained by the partner. Setting up financing via a public-private partnership (P3) allows risk to be transferred from the municipality and expands access to capital.
4. Once financing is obtained, a more detailed design is created, and construction can begin.
The complete process from initial feasibility to project completion can normally be expected to take about three to five years.
Value from Waste
As municipalities increasingly strive for zero waste—and sometimes net zero carbon emissions as well—technologies that can extract organics from their municipal solid waste will become more common. For many counties, reaping value from waste in the form of renewable natural gas, combined with job creation and sustainability benefits, will translate to significant economic and environmental benefits. | WA
Shayne Petkiewicz is Business Development Manager for Anaergia Inc, a global company offering anaerobic digestion and resource recovery solutions in the wastewater, agricultural and solid waste sectors. He can be reached at [email protected]