Garbage into Electricity at Sacramento County Landfill
Sacramento County's landfill is making something out of garbage; electricity. Through the collection of gases emitted from decomposing waste, the landfill runs the gas through its Kiefer Power Plant, creating electricity to sell to local utility companies.
"Combined, the engines in our plant create about 14 megawatts of power," said Tim Israel, the Senior Civil Engineer for the Department of Waste Management and Recycling. "That's enough to power about ten thousand homes."
The process begins by collecting the gases, which are composed of 50 percent methane and 50 percent carbon dioxide, out of the landfill through pipes that can be up to 30 inches in diameter. Like a funnel, the pipes start out small, going deep into the landfill waste, and eventually increase in diameter as they carry more and more gas to the plant. The pipes are installed in the trash vertically or horizontally, depending on the geography of the landfill.
Once the gas reaches the power plant, a compressor pushes it into the 15 by 30 foot internal combustion engines that convert it into electricity. Similar to the workings of an automobile engine, the engines roar to life with a roar that reaches approximately 115 decibels, or the same amount of noise as a jet engine. To dampen the noise, the building around the three engines was constructed with extra insulation. Each engine is comprised of 16 different cylinders, all spark-ignited and approximately one foot in diameter. The gas is burned and converted into electricity.
Prior to the construction of the Plant, there was a system that collected and burned off the gas through flares, without any monetary gain. In 1999, the County constructed the Plant at a cost of roughly $12 million. The new system not only removed the gas from the landfill, protecting the environment, but provided a new source of revenue to help offset costs. The County currently sells the electricity to the Sacramento Municipal Utilities District (SMUD), who then sells it to merchants and residents.
Because of new greenhouse gas regulations and renewable energy standards, such as the Clean Air Act and AB32, there is heightened interest in purchasing renewable energy sources. AB 32 set the 2020 greenhouse gas emissions reduction goal for California into law, requiring that over time greenhouse gas emissions are to be reduced from current trends. Because the electricity's value has increased, the County is selling the electricity at current competitive rates which could bring in an additional $2.5 million each year.