Leaving telltale signs that may be traced to renewable natural gas (RNG) from animal waste, Pacific Gas and Electric Co. (PG&E) and its alternative energy partner BioEnergy Solutions struck paydirt last week in a biogas-to-pipeline injection project in the agricultural fields of Fresno County in California. It is the first project in the state to deliver pipeline-quality RNG to a utility, according to PG&E.

Under terms of a 10-year contract approved last year by the California Public Utilities Commission (CPUC), BioEnergy Solutions is obligated to provide up to 3 Bcf of RNG annually. Last year the San Francisco-based utility signed another 10-year deal for RNG with Microgy Inc. for up to 2.8 Bcf.

Up to 100 MW of renewable power in California could come from dairy cow manure and other livestock waste, according to California Energy Commission (CEC) studies from the past that PG&E is using as a guide for its development push in the area. Biogas comes from landfills, wastewater treatment plants and livestock.

Bakersfield, CA-based BioEnergy said its system reduces emissions of methane, a greenhouse gas (GHG) that is 21 times more potent than carbon dioxide, by 70% at a 5,000-cow dairy, developing potential carbon offset credits. BioEnergy CEO David Albers said his company has "an innovative way of bringing together dairies and power companies to generate a new source of green energy."

"Using proven technologies, we design, build and operate highly efficient biogas systems that enable dairymen to meet new air quality requirements and help utilities meet their goals for production of energy from renewable sources," said Albers, a third-generation dairyman.

Vintage Dairy, which is owned by Albers in western Fresno County near Riverdale, is BioEnergy's first project, with manure from the 5,000 milk-producing cows and calves flushed into a covered lagoon the width of five football fields and three stories deep. This process traps methane gas produced as the manure decomposes.

The methane is upgraded, or scrubbed, to remove corrosive materials to meet PG&E's environmental standards and then delivered to the utility through its pipeline. PG&E uses the RNG to deliver renewable electricity to its customers in central and Northern California.

Ultimately, PG&E thinks it can get as much as 5% of its natural gas used for power production from these biogas-to-pipeline projects in the agriculture-rich central valleys of California.

"With nearly two million dairy cows in California, there is great potential for the state's agriculture and power sectors to work together to address the challenges of climate change," said Roy Kuga, PG&E vice president of energy supply. "This project is yet another example of our company's commitment to add innovative forms of clean renewable energy to help meet our customers' future power needs."

According to the utility, the CEC's past studies have placed the state's overall future potential for biogas at about 370 MW, or the equivalent of about 11 Bcf RNG annually. The bulk of the new supplies would come from livestock sources. Landfill gas has an overall potential for about 230 MW. Wastewater treatment represents a potential for another 40 MW. Livestock manure-produced gas could grow by 100 MW.

CEC researchers in the past have written off substantial new landfill projects because "most of the opportunities for big systems [5-40 MW] are gone." Instead, they see generation from landfill gas as concentrating on 1 MW or smaller facilities.

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