Renewable Gas Interconnection Process

Learn about the interconnection process for Renewable Gas

Renewable Gas (RG) is gas from biogenic or other renewable sources, such as biogas, biomass, or power to Gas from renewable electricity that has been conditioned or upgraded to be interchangeable with traditional natural gas.

SoCalGas® Rule 45, “Standard Renewable Gas Interconnection”, describes the specifications, terms, and conditions adopted that must be met in order for SoCalGas to accept RG into its pipeline network.

The process begins with a renewable source, such as anaerobic digestion of landfills or landfill diversion facilities, dairies, and wastewater treatment plants.  The raw biogas is mainly methane and carbon dioxide with traces of other elements such as water, hydrogen sulfide, siloxanes, nitrogen, and oxygen.

Prior to injection into the pipeline, renewable gas must be conditioned and upgraded to remove or reduce non-methane elements to promote the safe and reliable operation of the pipeline network and end-use natural gas equipment.

Biogas Processing Technologies

There are several methods and technologies available to condition biogas. Technology selection can be based on many criteria, including renewable gas source and product gas makeup as well as site and operating conditions. Some examples of technologies used in biogas conditioning include:

  • High-selectivity membranes
  • Pressure swing adsorption systems
  • Water scrubbing systems
  • Solid scavenging media
  • Regenerative or non-regenerative adsorbent media
  • Catalytic 02

It is common to find a combination of these technologies working in conjunction to meet a set of specifications.

Biomethane Injection Process

SoCalGas Rule No. 45, "Standard Renewable Gas Interconnection," provides detailed information on the requirements to interconnect and inject renewable gas into utility pipelines. The section below describes the three basic steps of the interconnection process.

Step 1: Interconnection Screening Study

The process starts with the execution of a Service Agreement and Confidentiality Agreement and request for an Interconnection Screening Study, which determines the utility's downstream capacity to take the renewable natural gas away from the interconnection point. The utility provides one free Interconnection Screening Study per project and requires up to 15 business days to complete and return to Interconnector1.

Step 2: Preliminary Engineering Study

The Preliminary Engineering Study (PES) requires an Attachment A-1 agreement and develops the Total Installed Cost estimate within +100%/-50% and preliminary Piping and Instrumentation Diagrams (P&ID’s). lnterconnectors must pre-fund the Preliminary Engineering Study. The PES costs approximately $100,000 and typically requires 90 business days to complete1.

Step 3: Detailed Engineering Study

The Detailed Engineering Study (DES) requires an Attachment A-2 agreement and develops the Total Installed Cost estimate accurate to +50%/-30% and Issued for Construction P&ID’s. lnterconnectors must pre-fund the Detailed Engineering Study. These costs typically start at $325,000 and requires 180 business days to complete and return to Interconnector1.

Biomethane Interconnection Incentive Program

In 2015, the California Public Utilities Commission (CPUC) established the Biomethane lnterconnector Monetary Incentive Program2. This program may provide an incentive that can contribute up to 50 percent of interconnection costs, with a cap of $3 million per project. The cap is $5 million for dairy cluster projects, defined as three or more dairies in close proximity. In December 2020, the CPUC approved an additional $40,000,000 into the Biomethane Interconnector Monetary Incentive Program of which SoCalGas was allocated $19,704,000 in additional incentive funds. During the same proceedings, San Diego Gas & Electric (SDG&E) was allocated $2,708,000 in additional incentive funds. The program is described in detail in SoCalGas Rule 45 Section I (5). Your SoCalGas account executive can help to navigate the qualification and application process for this incentive.

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1. The provided estimated costs are based on historical projects and can vary based on site­ specific conditions. The estimated costs and timeline does not include requests involving a deviation from the gas quality specifications.

2. D.15-06-02: This program is funded by California utility customers and administered by Southern California Gas Company (SoCalGas) under the auspices of the California Public Utilities Commission. Program funds, including any funds utilized for rebates or incentives, will be allocated on a first­ come, first-served basis until such funds are no longer available. This program may be modified or terminated without prior notice.

The information contained herein is made available solely for informational purposes. Although SoCalGas has used reasonable efforts to assure the accuracy of the information at the time of its inclusion, no express or implied representation is made that it is free from error or suitable for any particular use or purpose. SoCalGas assumes no responsibility for any use thereof by you, and you should discuss decisions related to this subject with your own advisors and experts.