The student tosses what remains of her grilled chicken salad into the trash can. From there, a garbage truck transports the scraps to a materials recovery facility where non-organics such as plastic forks are separated out.
A specialized process emulsifies the food waste into a bio slurry that gets pumped into anaerobic digesters or large, sealed tanks filled with bacteria that break down the material. Out comes biogas containing methane that is used to produce electricity or is converted into compressed natural gas and pumped into cars, trucks and buses for a cleaner-burning ride. The solids are converted into fertilizers for hay farms and backyard gardens.
For the 30,000 students eating meals at the University of California, Irvine, throwing away food is no longer considered a waste. It’s recycling.
From food scraps to energy
The university, along with supermarkets, food pantries, commercial catering businesses and restaurants throughout Southern California, are feeding a new kind of recycling revolution that turns food scraps into fuel, frees up landfill space and reduces air pollution. Playing a major role is Waste Management, a publicly held company, responsible for transporting food waste and converting it into a slurry, and the Los Angeles County Sanitation Districts, which pumps the slurry into existing wastewater treatment tanks and mixes it with sewage waste at the Districts’ Joint Water Pollution Control Plant in Carson.
Since 2014, the two have successfully run a four-year pilot project digesting about 62 tons per day, enough biogas to power the wastewater treatment facility.
On Jan. 24, the Sanitation Districts ended the demonstration program and signed an interim agreement with Waste Management to take even more food waste through Dec. 31, 2019. The districts received a $4 million grant from the state to build a permanent food waste system at the Carson plant that will receive as much as 550 tons per day of food waste slurry — nearly a tenfold increase, according to districts documents.
The project will go before the districts board for approval in a few months, said Mark McDannel, manager of energy recovery for the Districts Solid Waste Management Department. He said it’s too early to estimate the cost of the expansion.
McDannel said the Puente Hills Landfill Material Recovery Facility on Workman Mill Road near the intersection of the 60 and 605 freeways in City of Industry is already accepting food waste. Once a processing system is added in a few months, the facility will process up to 165 tons of food waste per day, which will be trucked to the Carson plant.
Powering cars, buses from waste
“From the demonstration program, we are converting it into a full-scale food recycling program,” McDannel said. The expansion will generate 1,450 cubic feet per minute of additional biogas, the equivalent of 9,000 gallons of gasoline per day, he said. Most likely, the districts will sell the excess energy to Southern California Edison to generate electricity.
A portion of the biogas, about 400 cubic feet per minute, equal to about 2,500 gallons of gasoline per day, will be converted into renewable natural gas — methane produced naturally and not from fracking — and then into vehicle-grade compressed natural gas. The fuel will be pumped to a nearby public compressed natural gas fueling station where it will be sold to drivers of CNG vehicles as well as school and transit buses, garbage trucks and fleet cars.
The California Energy Commission awarded the districts $2.7 million toward the $5 million compressed natural gas project, McDannel said.
Waste Management has used the pilot project as a model to launch others across the country. The company built projects in New York City and Boston, with a New Jersey food waste project set to go on line in a few months, said Eric Myers, director of organic recycling for Waste Management.
State laws pump up recycling
New laws for reducing greenhouse gases and increasing recycling have pushed the recycling of food waste in California.
The state’s target for diverting trash from landfills will jump from 50 percent to 75 percent by 2025, according to CalRecyle, the state agency that oversees recycling, from bottles to mattresses. Commercial industries are required to recycle organic waste.
Landfills can leak methane, which is a greenhouse gas contributing to global climate change and is also 30 times more potent than carbon dioxide in terms of trapping heat. The U.S. Environmental Protection Agency says landfills are the largest source of methane in the country.
Also, for every cubic foot of renewable compressed natural gas produced, less CNG needs to be pulled out of the ground by fracking, which can cause earthquakes or contaminate water basins. Finally, extracting renewable energy from food waste could encourage more schools and trucking companies to convert from diesel or gasoline to CNG, reducing the amount of harmful particulates and greenhouse gases emitted into the air.
Waste Management is one of a handful of companies working on recycling food waste. Many experts say the country has a long way to go to tackle the problem.
Food waste makes up about 18 percent of all the material in California landfills, according to CalRecyle. Each year, that equals about 6 million tons of food thrown away by Californians.
“We are trying to meet the community’s needs to recycle,” Myers said. “The amount of wasted food in this country is tremendous. About 40 percent of the food we generate is never eaten.”
