Extracting the Power of Biogas
Extracting the Power of Biogas
Extracting the Power of Biogas
2 minute read

The state of California has strict environmental regulations, requiring that utilities embrace renewable energy sources by 2020, taking on 33 percent of the state's energy sources. Biogas is becoming a viable source of this energy, prompting facilities to make the change.

The state of California arguably has the strictest environmental regulations of any state in the country. The state as a whole already embraces renewable energy sources, such as wind and solar, and by 2020, 33 percent of the state's energy sources must be renewable.

"Over the past 10-15 years, as the state of California has made environmental regulations increasingly strict­, almost all power plants run on a combination of natural gas, wind, solar geothermal and other sources of renewable energy," says Patrick Hirl, project manager for Burns & McDonnell. There are only two coal-fired plants left in the state."

A New Look at Biogas

As a result of the emphasis placed on renewable energy sources, Southern California Gas Co., the largest distributor of natural gas in the country, has turned its focus to biogas. Biogas is a renewable resource and is the product of the decomposition of organic matter in wastewater treatment plants, cattle manure, food waste and landfills.

In some cases, biogas is conditioned for combustion in a reciprocating engine or microturbine for electrical power generation. But in many wastewater treatment plants and landfills, biogas is burned off, or flared, because it is does not meet the requirements for use as a pipeline gas.

"Flaring the biogas from organic matter is not a problem in terms of damage to the environment because the carbon being released is already part of the current carbon cycle," Hirl says, "but it's a waste of energy."

Realizing the potential biogas holds as a renewable energy source, Southern California Gas is investigating a new technology to extract pipeline-quality natural gas — methane — from biogas emitted from a wastewater treatment plant in Escondido, Calif. The process, pressure-swing adsorption (PSA), works to separate gas species — specifically carbon dioxide from methane.

As owner's engineer for Southern California Gas, Burns & McDonnell helped identify potential technology providers, and Southern California Gas ultimately chose Canada-based Xebec because it could provide the purest form of methane through the PSA process and guarantees meeting — and even exceeding — California's standards for natural gas in pipelines.

"Southern California Gas is taking the first steps in the industry to find alternatives to natural gas that are renewable," Hirl says.

Environmental Win

These efforts to reduce reliance on fossil fuels as the main source of energy for power plants not only ensure a supply of natural gas, but also put the carbon cycle a step closer to being balanced.

"Right now, the main source of natural gas is fossil fuels, and the carbon released from burning that natural gas was pulled from the environment thousands of years ago," Hirl says. "But natural gas extracted from biogas contains carbon from within the last couple of years and is still considered part of the current carbon cycle. So it would reduce the amount of old carbon being released and reduce greenhouse gases."

It also helps pave the way to completely eliminating fossil fuels.

"That is a vision people have," Hirl says. "Although we're a ways away from it, there is the potential to completely eliminate the use of fossil fuels."

For more information, contact Patrick Hirl, 952-656-3634.

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