Building upon the momentum of a public private partnership (P3) that delivered energy neutrality to Victor Valley Wastewater Reclamation Authority (VVWRA)'s Water Resource Recovery Facility (WRRF), VVWRA and Anaergia teamed to implement California's first WRRF-based pipeline renewable natural gas (RNG) project. This initiative demonstrates the critical role WRRFs of all sizes can play to combat climate change, increase resilience, and create alternative revenue streams.
Background: VVWRA operates a 14MGD advanced treatment facility in Victorville, CA. VVWRA sought to better utilize biogas, offset electricity costs, minimize energy price fluctuations, and achieve net-zero operations. Typically, facilities of this size have limited ability to accept outside waste, and produce insufficient biogas to offset energy demand. To achieve these goals and mitigate risk to the Authority, VVWRA partnered with Anaergia to design, build, and finance upgrades to increase digestion capacity and deploy biogas utilization infrastructure. Anaergia provided its Omnivore high-solids digestion package to retrofit a 300,000-gallon anaerobic digester, forgoing the need for additional tank volume. These upgrades significantly increased digestion capacity and solids destruction, allowing for the introduction of energy-dense organic wastes for co-digestion. In addition to digester retrofits, high-strength waste (HSW) receiving was installed, enabling receipt of up to 20,000 gallons per day. As biogas production increased, Anaergia procured two 800-kW dual-fuel combined heat and power (CHP) modules, which began operation in 2016. The system was sized to utilize all WRRF biogas and meet 100% of VVWRA heat and electricity needs. VVWRA realized significant cost savings from offset utility consumption and benefits from enhanced resilience.
Objective: The first phase of this partnership demonstrated operational and economic benefits of an organics-to-energy program for VVWRA. Further, it highlighted demand for alternative outlets for organic waste disposal, driven in part by landfill diversion mandates such as California Senate Bill SB1383. These mandates aim to reduce methane emissions from organic waste in landfills, which can instead be leveraged to generate renewable energy and offset fossil fuels. As a result, VVWRA sought to maximize use of remaining excess digester capacity to increase co-digestion of external HSW and expand on benefits realized thus far â€“ namely, delivery of valuable WRRF infrastructure upgrades, increased biogas production, and ultimately increased financial benefit under a P3 arrangement. A key consideration in further expanding biogas production was determining the most valuable use of biogas, and the most economical way to fuel the cogeneration engines.
Application: Anaergia worked with VVWRA on cost-benefit analysis to determine the most economically favorable beneficial use of increased biogas. At the scale achieved from an expanded co-digestion program, it was concluded that all biogas should be conditioned and upgraded to RNG for injection into the Southwest Gas pipeline. To maximize value to VVWRA, biogas would no longer be used to fuel the cogeneration system, which would instead run-on utility natural gas. Based on RIN and LCFS credit values vs. commodity prices, analysis confirmed that value of RNG sales more than offset the cost of natural gas purchases for CHP. The conclusions are consistent with findings of similar biogas projects throughout California and North America: when sufficient biogas production scale is achieved, maximizing biogas to pipeline RNG creates greatest value, even where CHP systems are in place. This is compounded by higher operating expenses for biogas CHP compared to biogas upgrading. This approach has added benefit of generating carbon-negative fuel, an invaluable tool in achieving carbon-neutrality goals and mitigating climate change. Project Overview: The public private partnership (P3) includes WRRF upgrades for expanded co-digestion (new liquids receiving station, high-solids mixers in each digester) and biogas utilization facilities (biogas conditioning, RNG membrane upgrader, and utility interconnection). Ancillary upgrades (e.g., dedicated digester feed lines) were provided to support overall WRRF operations and address capital improvement needs. The project tripled VVWRA co-digestion and associated biogas production. Under the P3, Anaergia provided design, construction, and financing. Anaergia owns and operates the biogas utilization facility, located on a parcel leased by Anaergia from VVWRA. Anaergia receives all biogas produced at VVWRA and provides conditioning (to remove contaminants such as H2S, VOCs, and siloxanes) and upgrading to produce pipeline-quality RNG. Carbon-negative RNG is 99% methane and delivered to the Southwest Gas point of receipt for pipeline injection and sale, offsetting fossil fuels. Anaergia manages interconnection and offtake agreements, as well as registration with state and federal renewable fuel standard programs to maximize renewable energy credits and RNG value. VVWRA will continue to own and operate co-digestion and ancillary upgrades. Given the well-established co-digestion program, VVWRA maintains responsibility for coordinating organic feedstock (charging $0.05/gal for HSW). VVWRA continues to benefit from energy resilience and electric grid independence via cogeneration using natural gas. In addition, VVWRA receives new revenue streams via lease payments from Anaergia, additional tipping fees, and RNG sales revenue sharing. Construction of RNG infrastructure began in 2020 and was completed in 15 months, sending RNG to Southwest Gas as of late 2021. Lessons Learned: Pairing existing public infrastructure with private investment provides an effective and responsible means to expand resource recovery capabilities, opening the door for ambitious and innovative initiatives. This partnership demonstrates a replicable model to transform wastewater treatment facilities into energy-neutral or -positive resource recovery centers. Private investment can revitalize existing infrastructure to support climate goals and advance a circular economy while limiting risk to agencies and ratepayers. The P3 model enables rapid project delivery at scale to provide meaningful environmental solutions. P3s are appropriate to provide much-needed infrastructure and create new revenue for WRRF capital needs and rate stabilization. Risk to agencies and ratepayers is limited: an experienced industry partner is responsible for project delivery and performance. WRRFs can focus on their core mission while sharing in the benefit of investment and revenue from resource recovery. Bioenergy projects need not impede â€“ and can significantly improve â€“ WRRF operations. Anaergia's compact biogas utilization facilities encompass less than one-quarter acre. Potential impacts to nutrient removal, solids handling, and dewatering are evaluated during development to identify necessary mitigation measures (e.g., Omnivore retrofits or sidestream treatment). Third-party financing may also be leveraged to address deferred maintenance and capital improvement needs beyond core project scope. Overall, P3 is an effective and appropriate tool to deliver infrastructure upgrades. RNG can maximize project value and climate impact. Anaergia analysis confirms it is generally most economically favorable for all biogas to be upgraded for pipeline RNG pipeline. RNG value is sufficient to justify investment in new facilities and increased utility natural gas consumption for existing systems. RNG value is driven primarily by federal and state renewable energy credits, which monetize the potential of carbon-negative RNG to reduce methane emissions, offset fossil fuels, and advance carbon-neutrality.
Building on a previous project that delivered energy neutrality to Victor Valley Wastewater Reclamation Authority (VVWRA)'s, VVWRA and Anaergia teamed to implement California's first wastewater co-digestion pipeline RNG project. This initiative demonstrates the ability of water resource recovery facilities of all sizes to prevent greenhouse gas emissions from organic waste and fossil fuel consumption, while improving infrastructure, increasing resilience, and creating alternative revenue streams.
Author(s)Darron Poulsen1; Margaret Laub2
Author affiliation(s)Victor Valley Wastewater Reclamation Authority, Victorville, CA1; Anaergia, Carlsbad, CA2
SourceProceedings of the Water Environment Federation
Document typeConference Paper
Print publication date Oct, 2022
Volume / Issue