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Turning Food Waste Green

Updated: Jan 29

Energy recovery expert Will Chen manages the infrastructure that helps SoCal cities meet new organic waste diversion goals while generating clean electricity and renewable natural gas.

Pile of harvested raw vegetables

Growing up in the San Marino neighborhood of Los Angeles in the early 2000s, William Chen loved to tinker with cars. At first, it was his parents’ 1998 Toyota 4Runner, then later his own 2003 Subaru WRX. He was always trying to squeeze more power out of each vehicle, make it louder or improve its handling. He even majored in mechanical engineering at UCLA, fully intending to work in the automotive industry.

Changing Gears

During those undergraduate years, however, Chen’s career took an unexpected turn, while his passion for high-performance cars stayed right on course. Today, that juxtaposition of life experiences is captured in a grainy, black-and-white photo that adorns the wall of his office at the Whittier, Calif. headquarters of the Los Angeles County Sanitation Districts (LACSD).

The photo shows a Porsche 911 being modified in the service garage of LA-based Singer Vehicle Design. Scrawled on the white masonry wall beside the car in the finest graffiti font are three words, “everything is important.”

For Chen, that phrase––an homage to Singer’s design philosophy that all aspects of a Porsche, even its smallest details, are important and should be enhanced as part of the company’s “re-imagining” process––also summarizes the way he thinks about his professional life.

Will Chen, Manager of LACSD's Energy Recovery Section.
Reducing Carbon Footprints

Today, as manager of the Energy Recovery Section of LACSD’s Solid Waste Department, Chen guides a team devoted to reducing Los Angeles greenhouse gas emissions by recovering and recycling harmful gases produced by landfills and newly-mandated streams of food waste.

And everything about his team’s work––from expanding LACSD’s food waste recycling program to operating landfill gas-to-energy facilities to creating renewable natural gas for transportation fuel––is important.

“We focus our efforts on developing and utilizing energy recovery technologies that can reduce costs for our ratepayers and help the region be more sustainable,” he explains.

Pursuing Excellence

The son of first-generation immigrants from Taiwan, Chen spent his pre-teen and adolescent years playing in piano competitions, playing basketball––“even though I lacked height,” he recalls––and taking as many advanced placement (AP) classes as possible. By his sophomore year of high school, however, the workload proved too much. Chen abandoned the piano in favor of sports and academics, focusing on AP classes, school orchestra, golf, and preparing for college entrance exams.

And even though high school was filled with pressure and hard work, he reminisces, “that period of my life offered a lot of opportunities to push myself, to get out of my comfort zone, and to do things I won’t ever have the chance to do again.”

Discovering Environmental Engineering

One thing Chen is happy he’ll never have to do again is to be a college undergrad in mechanical engineering. He calls his experience at UCLA “humbling,” an opportunity to compete––at times unsuccessfully––with pre-med students who had skipped opportunities to attend the Ivy League schools in favor of “easier” UC schools where they could be at the top of their class.

Chen's undergraduate years at UCLA were challenging but did produce a career-defining opportunity with LACSD. -- Brooks McKinney photo

Chen’s UCLA years did, however, produce an internship with LACSD’s Energy Recovery Section, an experience that disrupted and forever changed the trajectory of his career.

From the summer of 2004 after his freshman year through 2008 when he graduated UCLA, Chen spent winter and summer breaks learning the inner workings of many of LACSD’s most productive energy recovery facilities.

And it put any thoughts of pursuing an automotive career in his professional rear-view mirror.

In 2009, LACSD offered Chen a full-time job as an operations engineer at its Calabasas Gas-to-Energy facility––and he’s been with the agency ever since. Along the way, his supervisors encouraged him to pursue a master’s degree in environmental engineering, which he completed at USC in 2010.

Letting Waste Go to Energy

Today, LACSD’s Joint Water Pollution Control Plant (JWPCP) in Carson, Calif. provides primary and secondary treatment of 250 million gallons of wastewater per day and serves more than 3.5 million LA County residents, businesses and industries.

Digesters use bacteria to break down organics to create biogas -- LACSD photo

A key by-product of this process is nutrient-rich solid organic material, which is treated in large (4.5 million gallons), heated, anaerobic chambers called digesters––not unlike the human stomach.

Bacteria in the digesters break down the organics, creating more bacteria and biogas, a mixture of carbon dioxide (CO2) and methane (CH4).

LACSD combusts this biogas on-site to produce electricity––more than enough to meet JWPCP’s power requirements––or extracts CH4 from the gas to produce renewable natural gas (RNG). The agency sells this “homemade” RNG––RNG is approximately 90% methane compared to the 99% methane content typical of fossil-fuel-based natural gas––as automotive fuel at its on-site CNG fueling station.

"What I love about this job is that LACSD gives us the trust and ability to run with ideas.”

-- Will Chen

Energizing Food Waste

Unfortunately, explains Chen, human waste is not the only source of biogas, whose major components are environmentally harmful greenhouse gases. It is also produced naturally in the compacted, anaerobic environments of solid-waste landfills by methane-producing bacteria as they break down organic waste. Some landfills have extensive systems to capture landfill gas while others let much of it escape.

Mindful of methane’s harmful environmental impacts, Chen advises, “the State of California has mandated that municipalities must begin diverting organic waste from landfills and should strive to recover and reuse the energy produced by the breakdown of that waste.”

Will Chen checks in on LACSD’s Puente Hills Materials Recovery Center where food waste from supermarkets, restaurants and food producers is accepted and prepared for processing in the agency’s anaerobic digesters. LACSD photo

Which is why Chen and his team have developed a robust food waste recycling program for LACSD. The agency began experimenting with the concept in 2014, but their work has gained urgency in the wake of SB 1383.

Ramping Up Biogas Production

Food waste recycling involves grinding organic waste into a slurry, then introducing it carefully into the stream of human waste that feeds LACSD’s anaerobic digesters. The food waste produces a steady stream of biogas that’s used to generate electricity for JWPCP operations and create RNG transportation fuel.

tanker truck waiting in front of 4 slurry tanks at JWPCP
Tanker trucks deliver more than 500 tons of food waste slurry per day to JWPCP. -- LACSD Photo

Chen’s team also captures biogas generated by the decomposition of trash in landfills. At several of its facilities, including the Calabasas Landfill Gas-to-Energy Facility and the Puente Hills Landfill Gas-to-Energy Facility, biogas is used to generate electricity which is then sold back to the Southern California electrical grid. Landfill gas, however, has higher levels of nitrogen and other gases, which makes it more difficult and more costly to convert into transportation fuel.

Anticipating Biogas Futures

For Chen and LACSD, the plethora of biogas has created both opportunities and dilemmas. For one thing, biogas cannot be stored economically. It must be combusted in real time to generate electricity, dispensed into vehicles as a transportation fuel––or flared (burned) off.

“If we create more biogas than we can use, we're literally letting revenue go up in smoke,” Chen says.

LACSD sells biogas-sourced transportation fuel at a CNG fueling station near JWPCP in Carson, Calif. Brooks McKinney photo

Chen is optimistic about the heavy-duty trucking industry's move away from using diesel fuel toward using RNG, which should expand LACSD’s market for biogas-derived RNG. But he's also mindful that the world of EVs is growing rapidly, which could depress the need for RNG and increase the demand for clean electricity. Ultimately, he hopes to position LACSD to feed its excess RNG into a regional natural gas pipeline that would reduce the need for fossil-fuel-derived natural gas.

Waking Up the Daily Grind

Work days begin early in the 3-bedroom house in Pasadena that Chen shares with his wife––his college sweetheart and now a nurse––and infant son.

When the alarm goes off, he checks on the baby, packs his lunch, then tackles his daily coffee ritual of measuring, grinding and brewing his coffee beans just so––“I’m a coffee nut,” he admits. After breakfast, he makes the 30-minute commute to his office in Whittier in a company-owned Chevy Bolt.

Chen’s workdays are filled with meetings with LACSD management, his team––12 engineers report to him––and the more than 60 mechanical and operational maintenance staff who report under his organization. The biggest challenge, however, is keeping up with his email inbox.

“I use my inbox as sort of a to-do list,” he says. “If an item is in there, it requires action. I used to be able to shrink the list, but now it just seems to be growing nonstop.”

Delivering on the Promise

For Chen, every day at LACSD is a humbling, exciting and professionally rewarding experience.

“What I love about this job is that the agency gives us the trust and ability to run with ideas,” he observes. “Over the years, I’ve been able to take ideas from inception on pen and paper to facilities that are now operating economically and producing renewable resources. Not many people have the opportunity, the engineering staff, the financial resources or the (management) trust to do that.”

Making Everything Important

And as the black-and-white photo on Chen's wall reminds him daily, the success of his team’s food waste recovery program, its efforts to capture and profit from the resulting biogas, and ultimately its efforts to reduce LA’s greenhouse gas emissions boil down to understanding and managing the details … all of them.

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If you enjoyed reading this post, I think you’ll also enjoy my profile of Glenn Acosta, a PR pro with LACSD who tells the story of constructing a new, high-capacity treated wastewater tunnel that will protect LA waterways. If you’d like to recommend a topic or person to be profiled in this blog, please send your ideas to

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