SoCalGas, Escondido demonstrate biogas technology

By Anna Austin | February 09, 2011

Southern California Gas Co. (SoCalGas) and the city of Escondido in southern California have begun testing a biogas purification technology at the city’s wastewater treatment plant that, if successful proved, would allow the gas to be directly injected into a natural gas pipeline.

What makes the system unique in nature is that instead of burning or flaring the methane without generating energy, which is currently done at the facility and is typical at wastewater treatment plants because the gas is not suitable for pipelines, the pressure swing adsorption system takes the raw gas originating from sewage, upgrades and purifies it through a multistate process to meet pipeline-quality gas standards for direct injection. Quebec-based Xebec Adsorption Inc. provided the technology.

Denise King, SoCalGas spokeswoman, said the company has been working with the city for more than a year on the project, which is being funded by the company’s research and development group. “We’re testing this technology and validating that it can consistently, reliably produce methane gas that meets the stringent California gas standards for injection into the pipeline system,” she said. Testing will continue for the next 12 months.

With completion of the demo project, there are a number of options as to what the next step will be, a likely one is that the city will choose to commercialize the equipment and keep it on site, according to King.

If the city makes that decision, some other costs would be involved, including an interconnection with the pipeline system, but it would eventually save ratepayers money.

 “We’re very excited about this project, because it’s the first in California and there’s only one other similar project in the U.S.,” King said. “If the technology proves itself, it would open up a whole new market for renewable natural gas that could be used by electric utilities to create green power. Yesterday [the system] was producing 99.9 percent methane, and that’s exactly what we want and expect.”

SoCalGas has been closely evaluating the potential for a renewable natural gas market, according to King. “We’re looking to help create the market, talking with dairies, wastewater treatment facilities and others that have organic waste. “

The opportunities to transform organic waste into power are seemingly boundless, King points out. For example, Gills Onion, the largest onion producer in California, uses its waste to produce energy to power fuel cells on-site. “In California, there’s probably enough organic waste to produce 16 percent of the state’s energy,” King said. “We think this is a growing market, and we’re working to help make it happen.”