Biogas Enhancement Project

Background

Sacramento Regional County Sanitation District (SRCSD) has a partnership with Carson Energy, which operates an on-site cogeneration plant at SRCSD's Sacramento Regional Wastewater Treatment Plant (SRWTP) in Elk Grove. The cogeneration plant is partly fueled by the biogas produced by SRWTP's digesters.

The biogas is produced in anaerobic digesters, which are part of the solids digestion process. Anaerobic digesters are large covered tanks equipped with mixing, heating, and gas collection systems. Anaerobic bacteria in the digesters convert organic matter into carbon dioxide, water, and methane.

In addition to fueling the cogeneration plant, the biogas provides renewable energy for the Sacramento Municipal Utilities District (SMUD) and emergency power for SRWTP in the event of a major power failure.

Project Overview

Construction of Biogas Enhancement Facility

SRCSD and SMUD conducted a Biogas Enhancement pilot test that evaluated the feasibility of using other waste materials, such as fats, oils and grease (FOG) and food processing waste (FPW) such as off-specification soda pop waste. Both waste materials were injected directly into an anaerobic digester to generate additional biogas. The pilot test assessed what effects the new waste materials would have on the existing anaerobic digestion process, including quantity and quality impacts to biogas production, amount of additional residual biosolids that will be produced and require disposal, and assessment of waste material handling and storage needs.

The test confirmed that introduction of FOG and other FPW's such as off-specification soda pop into the anaerobic digesters located at SRWTP improved overall biogas production and would result in the additional production of electricity from this green energy source.

With the results of the pilot test concluded, SRCSD began construction of a full-scale Biogas Enhancement Facility (BEF) at SRWTP in February 2012, as part of the region's renewable energy efforts. The newly constructed facility will increase the production of biogas already being produced at SRWTP. The additional biogas captured will be used by SMUD to generate renewable energy at SMUD's Cosumnes Power Plant located in southern Sacramento County. The facility will also provide a new local disposal location option for commercial haulers of FOG and liquid FPW.

In December 2012, operational testing was completed. SRCSD staff is currently making minor process improvements to the facility. Staff anticipates that the facility will be fully-operational by March 2013.

Costs and Funding

SMUD and SRCSD received approximately $1.45 million in American Recovery and Reinvestment Act funding from the United States Department of Energy and $100,000 in matching funds from the California Energy Commission to help construct the FOG receiving station which will enhance the current biogas production. The remainder of the project will be funded by SRCSD. The construction cost of the receiving station is approximately $2.1 million.

Project Benefits

• Saving local businesses money by providing an advanced, local receiving station for wastes that can reduce fuel and fleet costs associated with trucking the waste to distant locations;
• Increasing the production of biogas which will be used to generate renewable electricity for up to 1,000 homes in the region;
• Utilizing existing waste processing and power generation infrastructure to minimize capital costs;
• Eliminating greenhouse gas emissions associated with organic waste in landfills and its transportation to disposal sites outside the region; and
• Reducing the amount of wastes entering the local sewer collection system.

Photos

• March 2012 Construction
• April 2012 Construction
• June 2012 Construction
• August 2012 Construction
• September 2012 Construction
• October 2012 Construction
• December 2012 Construction

Documents and Reports

• Press Releases
  • March 2012 (220K pdf*)
• Status Reports and Updates
  • July 2011 (148K pdf*)
  • December 2011* (225K pdf*)
  • January 2012* (215K pdf*)
  • April 2012* (227K pdf*)
  • June 2012* (84K pdf*)
  • August 2012* (25K pdf*)

Construction Timeline

Construction of the BEF was completed in December 2012.

Questions

We encourage you to check this Web site for updated project information. To speak with someone regarding this project, please contact Jose Ramirez at 916-876-6059 or via email at ramirezj@sacsewer.com.

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