S.D. to sell sewage facility's excess gas

Project would capture methane from Point Loma

Capacity issues would be alleviated at the Point Loma Wastewater Treatment Plant under the city's recycled water plan.
Capacity issues would be alleviated at the Point Loma Wastewater Treatment Plant under the city's recycled water plan. — Peggy Peattie / U-T

Online: For a detailed look at the process of turning waste into electricity and the proposal to transport excess methane, go to uniontrib.com/more/methane

You can hardly see the flames from three stacks on a Point Loma cliffside, but you know they're there by the way their heat distorts the view of the nearby hills.

It would be a romantic spot with a view of the Pacific – but for the giant sewage plant below.

That's where countless bacteria eat away at everything San Diegans flush down the toilet, in the process producing 1.1 million cubic feet of methane gas that has to be burned off every day.

Now a private company, in partnership with the city, is planning to capture that gas and use it to generate electricity elsewhere, making money for the city and reducing pollution.

The project would capture the excess methane now burned at the Point Loma Wastewater Treatment Plant, purify it, compress it, then truck it to two or three locations around the region.

There, power plants would use it to generate 4.2 megawatts of electricity, enough for about 2,700 homes.

Methane, the byproduct of decaying biological matter, is a greenhouse gas, capturing 20 times the heat of carbon dioxide. It's flammable and has been used to generate electricity at landfills, big farms and wastewater treatment plants for years.

Much of that power is used to run the facilities where it is produced and the excess is sold. The Point Loma plant is methane-powered, and generators using methane at five San Diego County landfills generate 16.7 megawatts.

What makes this project different is that the gas would be trucked miles away for use by others.

“This is the first time it's being done in the country,” said Frank Mazanec, managing director of BioFuels Energy, the Encinitas startup company that is partnering with San Diego officials on the project.

The City Council approved 10-year contracts last week that call for the city's wastewater agency to get $260,000 a year from selling the gas it's now burning.

“What's important to the city is we're going to make money from it,” said Thomas Alspaugh, a senior mechanical engineer shepherding the project.

The city is not only selling the fuel, but it will buy one-third of the electricity it produces – at rates below what it now pays San Diego Gas & Electric – to run a sewage plant in San Ysidro for a savings of $78,000 a year, he said.

The $35 million Point Loma proposal is possible because of $17 million in state grants, $8 million in federal tax credits for renewable-power projects and $10 million in tax-free bonds, according to BioFuels.

If the project succeeds, it will reduce pollutants and make power from renewable sources.

“Basically, you get a double bang for your buck,” said Molly Tirpak Sterkel, who oversees renewable-energy subsidies for the California Public Utilities Commission.

As San Diego's population grew, methane production at Point Loma outstripped the needs of the generator there, and city officials were stuck flaring off the excess gas.

“We couldn't use it,” Alspaugh said.

With no room to expand the 4.5-megawatt power plant and an inadequate connection to the electric grid, the city sought a way to sell the gas it was simply throwing away.

It finally settled on the trucking proposal, which is keyed on transporting the methane elsewhere and running it through fuel cells, which are more efficient than traditional power plants.

The fuel cells use chemistry akin to that in batteries to convert fuel into electricity, water and carbon dioxide. Pollution is a fraction of burning the gas.

But fuel cells cost 3½ times as much as traditional power plants for the same amount of power.

That's where the state comes in. Using money from electric bills statewide, state officials are subsidizing fuel cell purchases in hopes of reducing the number of new, big power plants and power lines by generating power where it is used.

The grants are bigger if the cells are fueled with methane from renewable sources. About one-third of the 78 fuel cells the state has subsidized so far use methane from landfills, sewage plants or farms, Sterkel said.

Such waste methane isn't always found in the right place or the right quantity, which is why the local proposal makes sense, she said.

“They're innovating by trucking the fuel,” she said. “They're finding a way to make it work.”

The Point Loma project is a sign of things to come, said Andrew McAllister, who oversees state renewable-energy subsidies in San Diego County at the California Center for Sustainable Energy.

“That gas is a great resource and should be taken advantage of,” he said.

Still, the part of the project that makes it unique, the trucking, has a Point Loma community activist worried that the huge vehicles ferrying compressed methane over hilly streets pose too big a hazard.

“They're going to be rumbling down Catalina at night,” said Jim Gilhooly, a traffic engineer who opposed the project when it was under consideration before a local planning group last year.

The planning board ultimately backed the project after helping choose the route the trucks would travel on their six daily round trips.

“Trucking is common on those roads at night,” Alspaugh said.

Gilhooly suggests selling the excess methane to the Navy or generating the electricity at Point Loma and putting it on the grid.

But city officials and Mazanec of BioFuels say either of those proposals would miss out on the state grants and federal tax credits, making the project uneconomical.

The Point Loma proposal has Mazanec thinking of ways of using gas somewhere other than where it's produced.

With deals in the works with Washington state landfills, his company is hoping California will subsidize fuel cells powered by methane from farms or landfills hundreds of miles away. That's not possible at this time, but a proposal before the Public Utilities Commission would authorize such backing.

“We have sources of gas that are up to three times larger than the gas available in Point Loma,” he said.

Before it deals with that, BioFuels still has some hurdles to clear with its current project.

With only one-third of the Point Loma methane needed in San Ysidro, the company is looking to secure one or two other large customers to host fuel cells and buy electricity.

Where the other fuel cells would go has not been determined, though the University of California San Diego is a possibility because it had a contract with Linde, a German company that had worked on the project before.

BioFuels stepped in when Linde backed out during last year's credit crunch.

UCSD spokesman Rex Graham, who touted the project in December, last week wouldn't say where the university stood on it.
