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Photograph by Jacqueline Ramseyer
Power City
By Daniel Hindin
Two years of planning will soon pay off for the city of Sunnyvale when it begins to export power generated from its closed landfill. City officials met with representatives of PG&E on Jan. 25, to finalize plans and conduct tests. Another test was scheduled for Feb. 1.
"There's a lot of criteria that have to be met," says Sunnyvale Maintenance and Facilities Manager Dan Hammons. "It's not common for a small generator like us to be exporting power. There are a lot of hoops to jump through. We have to install multiple protective devices, new wires, ground fault protection, new meters, and a lot of detecting devices. Besides all of this, there are a lot of contractual agreements and other paper work. My goal is that we'll be exporting by early February, but I'm being optimistic."
The Sunnyvale landfill, located at the very northern end of the city, closed seven years ago. When the city closed the landfill, city workers placed a layer of clay on top of it and installed what Hammons calls a reverse sprinkler system inside it. The vacuum of the reverse sprinkler system sucks methane gases produced by the decomposing garbage out of the landfill.
The Bay Area Air Quality Management District and the federal government require that gas produced by decomposition of garbage be collected and destroyed. Until recently, the city destroyed the gas sucked from the landfill by burning it in a large flare located at the Sunnyvale Water Pollution Control Plant (WPCP).
In 1997, the city installed a power generation facility (PGF) at the WPCP, which burns the landfill gas in two large engines, thus generating electricity. Beginning in November 1997, the city used this new flow of electricity to power 90 percent of the WPCP's operations. This eliminated the cost of buying electricity from PG&E in order to run the plant, while taking advantage of a natural resource that had previously been considered waste.
But for the past three years, the city hasn't been using the PGF to its full capacity. The PGF includes two 800-kilowatt (kW) engines, which means the facility can produce up to 1,600 kW. The plant can now generate twice as much power as previously gnerated.
"The step of investing in a power generation plant is very expensive," says Sunnyvale's Solid Waste Division Manager Mark Bowers, explaining why they didn't run the PGF at full power in the past. "The power wasn't worth enough to back up an investment in it."
But the city estimates that, if it cranks the PGF up to full power, it can produce approximately 3.5 million kilowatt hours (kWh) per year for export, while also running the WPCP at full power. Suddenly, in the midst of a power shortage, the investment may provide a payoff never before imagined.
"A year ago, we'd be lucky to get a nickel [per kWh]," Bowers continues. "We based our assumptions [for this project] that we would be selling for about 30 cents/kWh, but current rates are around 40 cents/kWh.
The city would stand to make $1.4 million by selling 3.5 million kWh at $0.40/kWh. However, the prospect that prices will remain that high for any significant length of time remains doubtful. The city, using significantly more conservative estimates developed before this winter's energy crisis, originally projected revenues to be just over $100,000.
Bowers says, "It's hard to predict what the actual sales rates will be; a lot of the sale information is being kept confidential."
But revenues from selling surplus electricity only figure as part of the economic equation. By running the PGF at full capacity, city officials estimate Sunnyvale will save $185,000 off its electricity bill each year.
In addition, because the state and federal governments consider power produced from landfill gas as "renewable" power that is more environmentally sustainable, the city will receive various financial incentives approaching $90,000 per year.
With total export revenues, savings and government incentives conservatively estimated at $377,300 in the first year of operation, the city stands to recover the full amount of the original project investment well before the first year of power exports.
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Sunnyvale, California Since 1994
