RANCHO SAN DIEGO –
Defunct landfills and water recycling plants apparently can make for good neighbors.
At least that is how county officials say things are turning out in Rancho San Diego. Methane gas formed by rotting garbage in the long-closed Jamacha landfill is being piped about 2,000 feet to an Otay Water District reclamation facility, which converts raw sewage into irrigation water.
The methane powers three county-owned microturbines at the Ralph Chapman Water Recycling Facility and gives the plant most of the electricity it needs.
“In this case, we're taking trash – garbage – and turning it into energy to recycle water,” county Supervisor Dianne Jacob said at a ribbon-cutting ceremony for the project Thursday. “I'd say that's a good deal in anybody's book.”
Methane is a greenhouse gas, and federal law prohibits many landfills from allowing it to be released into the air. Because it can be flammable, methane also presents an explosion hazard, according to the U.S. Environmental Protection Agency.
To get rid of the methane, many landfills collect and burn it, which reduces the damage methane inflicts on the environment but does not utilize its potential to create energy. The Jamacha landfill on Singer Lane, which stopped receiving trash in 1978, uses the gas for power.
The three microturbines are expected to generate about 1.5 million kilowatt-hours of electricity a year, enough to power about 150 households, said Irene Stillings, executive director of the nonprofit California Center for Sustainable Energy.
“It's good for the environment and it's cost-effective for the water district,” Stillings said.
A grant from the Center for Sustainable Energy covered $273,000 of the $700,000 project. The county paid the rest. The water district agreed to buy the power from the county at 7.65 cents per kilowatt hour for five years. Jason Forga, a senior civil engineer in the county's Landfill Management Section, said officials believe the electricity revenue will go beyond covering the cost of the turbines and the pipeline.
Forga said the county is hoping for $8,000 a month in revenue, which would recoup the expense for the project after four or five years. The county began using the methane for power in about 2001 when it began generating power at the landfill and sold it to San Diego Gas & Electric. That contract expired in 2005 and has since been renewed for temporary six-month increments.
The Ralph Chapman Water Recycling Facility produces up to 1.3 million gallons of water a day from sanitized sewer waste. The water then is piped to the east side of Chula Vista and used to irrigate a golf course, school playing fields, highway medians and other areas.
The county will supply the electricity at a cheaper rate than San Diego Gas & Electric and save the water district around $20,000 a year. It's a relatively small sum for an agency with an annual budget around $100 million, but officials say it doesn't hurt.
“We're talking about tens of thousands of dollars,” said Mark Watton, the water district's general manager. “Don't get me wrong. If I see tens of thousands of dollars, I'll pick it up.”
Although the landfill and water recycling plant are located a short distance apart, the two do not share a property boundary. That presented a problem for using methane to power the water plant because utility regulations only allow landfills to ship electricity to properties that are directly adjacent to the landfill. Engineers got around that requirement by building the pipeline to the water recycling plant and generating the power on water district property.
Watton said the generators have been running for about two months for initial testing and appear to be working as planned.
The agreement between the county and the water district runs five years with an option to extend. Armando Buelna, communications director for the water district, said the landfill is expected to produce methane for about 15 or 20 more years. Engineers say the quantity of gas the garbage releases could drop, however, leaving enough to power only two of the microturbines.
Jon Bonk-Vasko, a program manager for the California Center for Sustainable Energy, called the methane at the landfill “low-hanging fruit.”
Using landfill-generated methane for energy is an idea that has spread, according to Bonk-Vasko.
“It's becoming more common as the technology advances,” he said.
Alan Schnepf is a San Diego freelance writer.
