Going Green With Renewable Natural Gas From LACSD's Carson WWTP

The presentation will cover the development of biogas conditioning system (BCS)-1 completed in 2020 and the operations that led the Los Angeles County Sanitation Districts (LACSD) to commence BCS-2 at their Joint Water Pollution Control Plant (JWPCP) located in Carson, California. The planning, logistics, key project features, key project accomplishments, as well as operational performance and a high-level review of financial performance will be discussed. We will also discuss the current status of further enhancing the project through increasing effective storage capacity, capture and reuse of the carbon dioxide removed from the biogas, as well as potentially utilizing some of the renewable natural gas (RNG) to create a hydrogen fuel product. The BCS-1 project included design, construction, equipment procurement, and operations, maintenance, and monitoring (OM&M) of a biogas processing and treatment system for the LACSD at their JWPCP. LACSD elected to utilize the BioCNGTM system to process 400 standard cubic feet per minute (scfm) of biogas from the JWPCP anaerobic digesters to produce approximately 2,000 gasoline gallon equivalent (GGE) per day of RNG for direct use in an adjacent, existing, compressed natural gas (CNG) fueling station. The project included system engineering and design, permit assistance, project site demolition, constructing a block wall/fence surrounding the facility, selecting and installing BCS equipment, training, start-up, and acceptance testing. After the completion of BCS-1, LACSD elected to install a second storage tank to double the volume of gas to be stored, along with a booster compressor which will increase the storage pressure of the RNG produced. This project will significantly increase the effective storage capacity of the BCS in order to meet the demand of the CNG fueling station, which is being expanded to accommodate a larger number of vehicles, including CNG-powered semi-trucks which frequently travel from the nearby Port of Long Beach. The BCS-2 project has a similar scope to the BCS-1 project but is required to be a much larger system. BCS-2 is also a BioCNGTM system and is required to process 1,440 scfm of JWPCP biogas to produce approximately 10,000 GGE per day of RNG. The RNG produced by BCS-2 will be sent to both the expanded CNG fueling station and to a pipeline injection facility for injection into the local utility's natural gas pipeline. BCS-1 was started up in October 2020 and began running full time in September 2021. BCS-1 continues to operate today. Once BCS-2 is operational, BCS-1 may be used as a backup to BCS-2 or relocated to another LACSD facility. As of January 2024, the BCS Storage Modification and BCS-2 projects are in the design phase and are scheduled to be operational by the end of 2025. The BioCNGTM system utilizes multiple different technologies to convert biogas into RNG that is suitable for use as vehicle fuel or pipeline injection. Biogas is directed through a particulate filter to remove larger particulates and liquid droplets. The biogas is then sent to a compressor to increase the pressure of the biogas. The biogas is then treated with specialized granular activated carbon media to remove volatile organic compounds (VOCs), siloxanes, and hydrogen sulfide. The biogas is then sent through a membrane system to remove carbon dioxide, leaving a product of RNG that is at least 97.5 percent methane by volume. The RNG vehicle fuel produced by the BioCNGTM meets California Code Title 13; Statute 2292.5 compressed vehicle fuel standards along with SoCalGas Rules 30 and 45 for pipeline injection. By producing RNG from biogas that would otherwise be flared, these projects have helped LACSD in their goals of reducing air emissions and utilizing alternative fuels. As of January 2024, BCS-1 has provided over 9 million standard cubic feet of RNG to the CNG fueling station. This is the equivalent of approximately 730,000 GGE. LACSD receives revenue from the sale of the RNG, the California low carbon fuel subsidy, and the federal renewable fuel subsidy. With these revenue streams, the payback period for the approximate $6 million capital expense for the BCS-1 project is less than 5 years. The BCS-2 project is expected to have an even shorter payback period with the potential for tax credits from the Inflation Reduction Act.