Shoreline generator plan moving forward Shoreline generator plan moving forward (February 07, 2003)

Garbage-produced methane could help power Alza

By Candice Shih

A city plan is in place to harvest renewable energy from the tons of garbage beneath Shoreline Park.

The methane produced by 13 million tons of underground garbage is currently burned at a flare station. The new plan would burn the gas to power city facilities and very likely the offices of pharmaceutical company Alza, which are located next to Shoreline.

The landfill that sits beneath about 60 percent of Shoreline park naturally emits gasses, mostly methane and carbon dioxide. Methane can be converted into energy and constitutes 45 percent of Shoreline's landfill gas.

The gas is brought to the surface through a 50-mile network of underground pipes; if it was left in the ground, it build up and explode (concertgoers in the early days of Shoreline Amphitheatre experienced this firsthand when a leaky landfill cap released gas that ignited tossed cigarette butts).

It was during the energy crisis of 2001 that the city decided the potential energy source shouldn't go to waste. In addition, the state began offering subsidies and grants for projects that would reduce the demand on energy. Now, almost two years later, Mountain View's project will come to fruition.

"The power crisis was fairly short-lived. ... But we're still working on this project," said Gregg Hosfeldt, the city's business manager. "It's not something we've stopped because the glamour is off the issue."

Glamour or no glamour, come summertime the methane will be powering the flare station, a sewage pump system, and an irrigation pump station at the golf course.

The city will use two microturbines -- a relatively new technology -- to deliver the power. Each microturbine is a metal box the size of a walk-in closet, and can generate 70 kilowatts, enough power for 70 homes. It only takes about 3 percent of the landfill gas to power the microturbines 24 hours a day.

The city hopes to save $50,000 to $60,000 per year per microturbine on its PG&E utility bill. And, with the total costs to run the program reduced by $210,000 in state grants, the city's expendture will be made back in about five years, added Hosfeldt.

If only 3 percent of the gas will be used, then why can't the remaining usable portion of it go to power more buildings and machines? The answer, said Hosfeldt, is basically financial. It would simply be too costly to rip up miles of streets to lay in the pipeline that would run from the methane at Shoreline to your house or business.

It isn't economical to run a power plant or liquefy natural gas either. And although selling the energy to PG&E would generate some money, it wouldn't be profitable after setting up the needed infrastructure.

But Alza is close by on Charleston Road and could theoretically use a generator that is directly linked to Shoreline's methane gas. It would save Alza money and generate revenue for the city. According to Hosfeldt, the plans to sell energy to Alza are still in the conceptual stage and have not yet completed a feasibility study.

The Shoreline landfill was opened in 1970 and wasn't officially closed until several years ago, despite the development of the aboveground park in the early 1980s. As the waste decomposes, the ground sinks and depressions are made. It may continue to settle for at least 30 years, during which time the gas will be emitted.

E-mail Candice Shih at cshih@mv-voice.com