New Recipe for Airline Leftovers

Many a traveler has pondered how to dispose of unappetizing airline food.

Impatient for the flight attendant? How about jamming that tired fruit cup in the seat back? Or stowing a container of congealed stew under the chair?

An airline passenger’s fleeting concern has become, in essence, Louise Riggen’s job. For nearly a decade--as recycling coordinator at Los Angeles International Airport--she has tried to figure out how to reuse tons of food waste generated by a dozen airline catering kitchens.

She tried trucking it to an animal feed processing plant in Ontario. But that was too expensive. She considered worm farming and composting. But she couldn’t find nearby vendors. Finally, she found a possible answer right across the street from the airport.

Riggen teamed up with Gerald Hernandez, a sanitary engineer at the Hyperion Treatment Plant, to devise a pilot project that turns kiwi, asparagus and other food waste into electricity and compost.

The six-month program processes about 225 pounds of raw fruit and vegetable leftovers a week from Gate Gourmet--an airline caterer that volunteered for the pilot project. Riggen eventually hopes to recycle at least 8,000 tons of the airport’s food waste at Hyperion each year. That is more than 40% of the more than 19,000 tons collected annually from airport food concessions--an amount that rivals yearly trash pickups at popular amusement parks.

“This is where we want to go with recycling--toward sustainable systems for the economy and the environment,” Riggen said. “This way we’re not ripping off Mother Nature and throwing it in the dump.”

Riggen’s devotion to the work--not to mention her tie-dye fashions and penchant for organic foods--has earned her a reputation as the airport’s resident hippie.

Her search was prompted by a state law that required cities and counties to reduce the amount of trash they sent to dumps 50% by 2000. LAX, which is operated by the city of Los Angeles, met that goal, largely through programs that recycle everything from plastic sheeting to wooden pallets to cardboard and office paper.

If successful, the program at the Hyperion plant will simultaneously cut the amount of waste sent to landfills, produce needed electricity and help reduce disposal costs for the airport’s catering services.

Recycling Process Begins

On a recent foggy morning at the plant overlooking the ocean, an employee unloaded plastic buckets full of fruit and vegetable scraps and placed them in front of an enormous garbage disposer.

The machine, part of an experimental receiving station built for the project, is nestled among holding tanks that process 370 million gallons of raw sewage a day.

One by one, associate engineer Wendy Wert heaved the buckets up on her knee and poured strawberry tops, cantaloupe and watermelon rinds, orange peels and broccoli stalks into the disposer.

She added some old lettuce and flipped the switch. The smell of disintegrating orange peels filled the air--temporarily overpowering the lingering scent of raw sewage.

The disposer--eight times more powerful than clog-prone home versions--groaned as it ground the leftovers into a grainy, greenish paste. Then the stuff was piped into an open vat and mixed with water.

Next, the mixture was sent back through the disposer and piped into a holding tank. Inside the tank it was heated to 130 degrees to help bacteria more efficiently consume tiny bits of the leftovers.

This process eventually produces methane gas, which is sent to the nearby Scattergood Steam Generating Station, where it is burned to generate electricity.

The 30% of the food waste that doesn’t decompose is hauled away by truck to be turned into compost, Hernandez said. Water used in the Hyperion process is reclaimed and used in irrigation systems and in bathrooms at the treatment plant.

Initial studies show that recycling food waste will cost airline caterers about $12 a ton less than hauling it to the dump, Riggen said. By next summer, she hopes to truck waste from one caterer--72 tons--to the plant for recycling.

As for the half of the airport’s food-related waste that’s not eligible for the project--such as napkins and other trash generated by food concessionaires in the terminals--Riggen plans to ask those businesses to use corn starch flatware and biodegradable containers and trash bags. Those materials would eventually be sent to a composting plant instead of a landfill.

Hyperion, which generates enough electricity from sewage to power itself and send a small amount to the public grid, has the capacity to handle all of LAX’s food waste now. But engineers need to figure out the most efficient way to process and store the waste, Hernandez said.

Costs Versus Benefits

Alternative energy systems like the one LAX started at Hyperion--known in recycling circles as biomass--are more expensive than those that use nonrenewable fossil fuels. But proponents argue that additional costs are offset by environmental benefits.

“You’re not taking that waste to the landfill, and you’re not venting the gas it creates into the atmosphere,” said Claudia Chandler, assistant executive director of the California Energy Commission. “Secondly, you can look at transportation costs associated with hauling waste to the dump and air quality problems with trucking.”

Biomass’ critics say the method will never replace fossil fuels as a means to power millions of American homes, because there isn’t a system to channel biomass materials to market and there aren’t enough plants to process them.

Today, biomass systems account for only a tiny fraction of the state’s electricity--about 2%, or enough to power 646,000 homes. Most of the biomass energy produced comes from plants in Northern California that buy sawmill waste and burn it to create electricity.

“This is a new and emerging market as more companies look at various options to generate electricity from products that formerly would have gone to the landfill,” Chandler said.

As an alternative source of electricity, biomass has the potential to offset as much as a quarter of the nation’s fuel use, said Daniel Kammen, a professor in the Energy and Resources Group at UC Berkeley.

He envisions farms where biomass fuel like grass or wood would be grown and distributed to plants to generate electricity. But first, the energy industry would have to dedicate more resources to build plants with the capacity to handle biomass, Kammen said.

“We’re at the point where this could work,” he said. “The question is: Are we going to expand our biomass capacity or go in different directions?”