Plan Would Turn Marin's Food Waste Into Energy

February 10, 2009

Marin Independent Journal, Novato, Calif. 

Yesterday's garbage could become tomorrow's electricity in a new
plan under consideration by the Central Marin Sanitation Agency."The whole idea is to divert that food waste from the landfill
and turn it into renewable energy," said San Rafael Mayor Al Boro. "We
think there could be great benefits to the community with respect to
the reduction of greenhouse gases and the production of renewable
energy."
The plan, which the agency board will consider at a meeting
Tuesday, would take the food waste collected by Marin Sanitary Service
from restaurants and grocery stores and turn it into methane gas by
adding it to the sewage at the Central Marin Sanitation Agency's San
Rafael treatment plant.
However, some members of the Ross Valley Sanitary District have
questioned the proposal -- patterned after an existing food-to-energy
program at the East Bay Municipal Utility District in Oakland --
saying not enough is known about the plan.
"There are so many unanswered questions, including the real
cost,"
said Sue Brown, a member of the Ross Valley district board who also
sits on the board of directors for the Central Marin agency, which
serves San Rafael, the Ross Valley, Corte Madera and Larkspur. "The
East Bay MUD project is still in its pilot stage. There's been a lack
of information with regards to this project and a disparity in the
projected costs."
An on-site power plant at the Central Marin treatment plant
already produces enough electricity from sewage-generated methane to
run the plant for 12 hours a day. Adding food waste would make the
plant's methane digester more efficient, officials say, allowing the
agency to quit purchasing natural gas from Pacific Gas and Electric
Co. -- and possibly even allowing it to sell excess electricity back
to the utility.
"Basically, when you introduce food waste (to the methane
digester), the poop pops better," said Stephanie Lovette, economic
development coordinator for the city of San Rafael, where the City
Council voted last week to support the plan. "All the little bacteria
that are now eating waste get even more excited, and they produce more
gas."
According to waste hauler Marin Sanitary Service, food waste
makes up about half of the remaining garbage in its trucks after
recyclable items have been removed.
Taking that food waste to the sewage plant would cut down the
amount of garbage heading to the Redwood Landfill near Novato; that's
an idea Marin Sanitary Service favors, especially because the Central
Marin Sanitation Agency has proposed disposal fees lower than the
landfill's.
"The trip for us to take waste to the landfill is 16.4 miles;
this trip is only 0.5 miles, so that gives us a smaller carbon
footprint," said Patty Garbarino, president of Marin Sanitary Service.
"And the tipping fee would be about $20 versus the $54 we pay now at
Redwood. So this would be a big bump in our numbers."
Marin Sanitary Service is already participating in a pilot
program that converts food waste from about 12 San Rafael restaurants
into compost by mixing it with green waste.
"This program (food-to-energy) would take more out of the waste
stream than composting it in a biocell does," Lovette said.
"Composting also gives off gases," while the proposed project would
contain and use them, she said.
Agency officials say it would cost $2.7 million to update the
treatment plant to accept food waste -- money they expect to make back
in about eight years through reduced fuel costs.
"The cost savings to us from not buying natural gas would be
$350,000 to $400,000 a year," said Jason Dow, general manager of the
Central Marin Sanitation Agency, who estimated the agency's power
plant could eventually generate 90 percent more energy than it needs
to run the facility -- electricity it could sell to either PG&E or a
proposed Marin-based utility relying on sustainable fuels.
Dow insisted that the proposed system would be "safe, sound and
well-engineered" and would not add to the danger of a methane gas
explosion at the treatment plant.
"We have safeguards built into the instruments to monitor gas,
gas flow and gas quality," Dow said. "The addition of methane gas
would not add any risks."
IF YOU GO
The Central Marin Sanitation Agency Board of Commissioners will
consider a food-to-energy project at 7 p.m. Tuesday, Feb. 10 at the
agency office, 1301 Andersen Drive in San Rafael. For more
information, call 459-1455.
Contact Rob Rogers via e-mail at [email protected]