By Sean King, JDV Equipment Corporation
Waste comes in many forms. But some waste such as manure, fats oils & grease (FOG), left over or spoiled food, and pre-consumer process waste have unrealized value. Co-digestion facilities offer an opportunity to process and harness this waste as renewable energy and provide practical environmental impacts.
Manure applied as fertilizer has been common practice. Yet open lagoons of manure slurry cause strong odors when not processed prior to entering the lagoon. They also release harmful green house gases (GHG) and it just plain stinks. Our landfills also produce GHGs and are approaching or already are over capacity. In response, the Environmental Protection Agency (EPA) has set a goal of 50% diversion of food waste by 2030. Taking it further, the state of California has proposed legislation that bans ALL organics from landfills by 2025.
Where will all this diverted waste go and how will it be processed? Currently composting leads the processing of post consumer food waste, with anaerobic digestion (AD) facilities gaining traction as evidenced by the increased number of projects in planning, permitting and construction phases.
One such project is Heartland Biogas, located in LaSalle, CO. The facility will supply renewable natural gas (RNG) to the Sacramento Municipal Utility District (SMUD) through a 20-year Gas Purchase Agreement. SMUD has set a goal to have renewable energy account for 33 percent of its power supply by 2020. According to its 2015 sustainability report it is already approaching 30 percent.
Heartland Biogas is well positioned to help SMUD reach its 2020 goal. The 20MW anaerobic digester and RNG facility is one of the largest facilities in the United States, capable of producing up to 4,700 MMBtu of biogas daily.
During Phase I of the design-build project run by HDR Inc., JDV Equipment Corporation worked closely with engineers to design and supply six double membrane covers for each of the six 100′ diameter digester tanks. The AD system will convert a mixture of cow manure from local dairies and organic waste from local restaurant’s grease trap waste, spoiled grocery store products, cafeteria waste and food process residuals into biogas. The raw biogas will be processed into pipeline quality RNG that will be injected into the Colorado Interstate Gas Company pipeline to provide SMUD with another renewable energy source. Additionally, the waste will be used to produce organic compost and liquid soil fertilizer for use locally by the farms supplying the manure.
Co-digestion facilities like Heartland Biogas and stand alone AD facilities have been long been in place, but at a much smaller and local scale. There is now broader recognition of the positive environmental impacts and the ability to take advantage of waste as a renewable resource. Regardless of what laws are being proposed or are in place, valuing waste as a resource should be best practice along with conservation and avoiding unnecessary waste.