South Park Biodigester Fuels Model for Community-Led Sustainability

It has been a year since Seattle's first community-owned and -operated biodigester was launched in South Park, and the bright-blue tank is going strong, cranking out fuel and nutrient-rich fertilizer.

In the lead-up to its launch, the biodigester project was in the works for years as the brainchild of Edwin Alberto Hernández-Reto, executive director of Duwamish Valley Sustainability Association (DVSA). His organization is based in South Park, a predominantly Latino community wedged between Highway 509 and the Duwamish River.

Hernández-Reto is a mechanical engineer with a heart for South Park. He moved to the region in 2015 and spent his first few years living in South Park, where he fell in love with the community. He eventually moved farther south because of rising rents, but his work and dedication to South Park stayed put through his work with DVSA.

DVSA engages BIPOC youth — particularly those in South Park, which is overburdened by air pollution because of its proximity to highways and the airport — to become community activists trained in STEAM (science, technology, engineering, arts, and mathematics). The organization's youth programming takes a hyperlocal approach to addressing environmental issues and needs in South Park, from monitoring the water quality in Puget Sound and the Duwamish River to promoting recycling and waste reduction.

"Engaging young people now in these important issues allows them to learn about STEAM professions that are in high demand in our region and that are not well-known in our community," Hernández-Reto said. "If they decide to study some of these professions, it will allow them access to jobs with good salary ranges and with a more community-based approach."

As a community leader and innovator, Hernández-Reto saw the biodigester project as a primo opportunity that would kill several birds, so to speak, with one biodigester tank: It would serve as a hands-on science lesson for community youth. It would reduce food waste from local restaurants. It would create high-quality fertilizer for farms and community gardens in the area. And it would reduce emissions.

So, what's the small but mighty machine that can achieve all of this? A biodigester is a sealed tank that contains organic materials, such as food scraps, agricultural waste, and manure. The oxygen-free environment of the sealed tank allows for an anaerobic digestion process in which bacteria break down the organic waste. This captures and converts greenhouse gases, mostly methane and carbon dioxide, into biogas, a renewable source of energy. And it also creates a probiotic liquid fertilizer.

Biodigesters can be used on a large scale, such as on agricultural farms, to turn all of that livestock manure into fertilizer. They can also be used on a small scale, such as in someone's backyard, to break down food scraps and generate gas for cooking or heating. The South Park biodigester, from Chomp Energy and housed on Food Lifeline's lot at the southern end of the neighborhood, is somewhere in the middle, designed to demonstrate how a specific community can manage its own waste and bring it full circle — from food scraps to fertilizer and fuel that are fed directly back into the community.

Right now, the biodigester is consuming 675 pounds of organic waste from South Park restaurants, producing 180 gallons of fertilizer weekly. The project's goal is to create enough fertilizer to distribute it to community gardens around Seattle. Plus, Hernández-Reto says, the community could use the biogas as a form of alternative energy to offset the use of fossil-fuel-based energy sources. 

The community's use of this fertilizer and fuel is still in the evaluation phase. While the biogas is on hold for being tested as a source of energy, the fertilizer has been tested in several gardens around Seattle, including Yes Farm, the Danny Woo Community Garden, Dirt Corps, Green Futures Lab, and Black Star Farmers.

Yes Farm is a 1.5-acre green space and farm co-op in Yesler Terrace. More than just a space to grow produce, the farm serves as a natural classroom for youth and develops green space where people can gather.

Ray Williams, special projects director of Yes Farm, says the farm has already seen the fertilizer's effects. "We used it with some youth groups throughout the summer, and we definitely showed some improvement in the growth of the plants that were getting the fertilizer," Williams said.

Williams says the farm's relationship with DVSA has cultivated a cross-pollination of youth educational efforts. "We actually have some of the DVSA youth now coming out to our farm for a weekly information session and work sessions, like a class," Williams said.

The biodigester project has had a number of supporters who helped get it off the ground, including the University of Washington EarthLab and the Environmental Protection Agency. Regional organizations, like Seattle Parks Foundation, continue to evaluate the hyperlocal project's potential for replication on a larger scale.

Seattle Parks Foundation has provided fiscal sponsorship for the project and a staff liaison for coaching and support through the life of the project. It has also provided fundraising support and partnership connections.

"The practices we value most of this project are its equity-centered, community-led approach and its focus on circular solutions that can be replicated elsewhere," Shava Lawson, Seattle Parks Foundation's director of fiscal sponsorship, wrote in an email to the Emerald. "These all align closely with our mission to support grassroots leadership in creating thriving, equitable public spaces."

As the evaluation continues, Hernández-Reto says the biggest challenges are securing transportation for regularly distributing the fertilizer among Seattle-area farms and finding funding that would allow for upscaling the biodigester's output. DVSA is also seeking an area that would allow for a bigger biodigester.

Regardless, he has big hopes for South Park's mighty biodigester.

"With the biogas, we could use it for engine generation and create electricity and promote public transportation," he said. "Maybe we can use it in batteries and create charger stations for the e-bike scooters."