With continuing unfulfilled promise within the state's renewable energy mix, biogas, or "green" gas, could use a marketing boost, and Sempra Energy's two utilities said Tuesday they have plans to provide the jump-start in filings at the California Public Utilities Commission (CPUC). They expect a decision from regulators next year.

Southern California Gas Co. (SoCalGas) and San Diego Gas and Electric Co. (SDG&E) are asking the CPUC to approve rate support for utility programs in which they would develop, own, operate and maintain bioenergy production and gas conditioning facilities transforming organic waste from water treatment plants, farms and other operations into renewable (green) natural gas (RNG) that can go directly for electricity generation or be put in the existing gas pipeline mix for other end uses.

Some estimates for the state have indicated that biogas carries the potential for providing up to 16% of the state's natural gas needs, but RNG so far has not lived up to its potential, despite some major contracts and projects signed in the past four or five years by the state's major gas utilities, particularly Pacific Gas and Electric Co. (PG&E).

SoCalGas and SDG&E are proposing that the CPUC authorize them to rate base investments in the new facilities needed to provide a full range of biogas services. They envision owning and operating utility facilities on or adjacent to a customer's premises that have the needed waste sources.

The utility filings indicate that the bioenergy production facilities will work with a wide range of organic waste source material -- agricultural wastes, animal wastes, biosolids, energy crops, food wastes, green waste, manure, municipal solid wastes and sewage.

Under a long-term contract, the utilities would invest the capital required to provide gas conditioning and bioenergy production services for a fee, the Sempra companies said. Turnkey projects would be located on or near customer properties. If approved by the CPUC, the two utilities intend to share a portion of the profits with ratepayers.

In 2008 the California Energy Commission (CEC), which has touted biogas development in the state's integrated resource plan, estimated that up to 100 MW could come from dairy cow manure and other livestock waste alone. PG&E used this and other CEC data as a guide for its development push in the area (see Daily GPI, March 5, 2008).

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 with the bulk of the new supplies coming 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, according to 2008 CEC calculations.

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