LFG Technologies (LFG Tech) has significant experience with a wide range of applications. This section highlights our experience in developing LFG-to-RNG plants. LFG Tech developed this plant for Montana-Dakota Utilities at the City of Billings Municipal Landfill and feeds the high BTU gas directly in to the City of Billings natural gas distribution system. This may be the only plant in the US that does so. LFG Tech developed the project with an EPC approach providing Engineering, Procurement, Construction oversight and start up.
The Billings Montana landfill has two PSA systems in series, with no pretreatment of the landfill gas. The first removes CO2, water, VOCs and H2S in a single-step process, identical in materials and system operation as the system proposed in this quotation. The second PSA removes N2 to produce pipeline-quality gas. The Billings plant is designed for a feed flow of 1,600 SCFM with a feed gas methane content of 50%. The system has been operational since December 2010 and has been highly reliable, achieving 99.4% operational time during the 2017 calendar year. Besides annual maintenance, there have been no changes to the equipment nor replacement of media since system start-up.
Recent tests at the Billings plant were completed to evaluate the Molecular Gate™ PSA performance in removal of trace constituents identified in Southern California Gas Rule 30 and Pacific Gas and Electric Rule 21. Gas samples were taken at the raw landfill gas feed and at the product gas flow of the CO2 PSA. Constituents identified in Rule 21/Rule 30 as Carcinogenic Chemicals (i.e. p-Dicholorobenzene), Non-Carcinogenic Chemicals (i.e., Hydrogen Sulfide, Mercaptans), and Pipeline Integrity Chemicals (i.e., Siloxanes). All constituents detected in the feed stream were removed below the stated Trigger Levels or to non-detect levels. While these two very strict gas specifications may not currently be in force in the jurisdiction of this project, many additional states including Oregon and Washington have either adopted similar standards or are currently being considered for adoption.