Dairy Environmental Systems

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    Estimating anaerobic co-digestion influent-effluent volume differences: Background, Method, and Application
    James Morris; Curt Gooch (2024-02-14)
    Anaerobic co-digestion (AcoD) of dairy manure and a wide variety of off-farm feedstocks including pre- and post-consumer food wastes can improve economic feasibility of on-farm anaerobic digestion (AD). Added feedstocks can result in substantial digester effluent volume increases that must be properly managed and depend on the feedstock’s characteristics. Digester influent and effluent flow meters are the best primary measurement method for quantifying flows and supporting tipping fees; however, they are often not standard equipment on most farm systems. Absent adequate metering, acceptable influent-effluent digester volume reduction calculations can provide the basis for assessing additional material handling compensation, especially when systems involve third-party AD operators or off-farm owner-operators. When on-farm AcoD systems involving third-party partnerships are in place, it is important to determine the effect AcoD has on influent-effluent volume differences. This two-part fact sheet set summarizes a recommended method to calculate influent-effluent volume differences based on published work and provides an array of results applying this method on representative on-farm AcoD scenarios.
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    Covers for digestate effluent storage from anaerobic digestion
    Ray, Lauren (PRO-DAIRY, 2023-10)
    Dairy farms considering or already using anaerobic digestion of their manure have to account for the digestate effluent in their nutrient management planning. Impacts to volume of digester effluent compared to influent, digestate nutrient composition and remaining volatile solids that can convert to methane, are described. The option of using and impermeable cover and flare system on digestate long-term storage reduces precipitation volume and can yield additional carbon credits or value from the digester operation. An estimate of methane produced from digestate storage under varying conditions and a comparison to methane from raw manure storage is included.
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    Considerations for central anaerobic digestion of manure from multiple dairy farms
    George, Angela; Oliver, Jason; Ray, Lauren (PRO-DAIRY, 2023-03)
    Anaerobic digestion (AD) of dairy manure to produce renewable natural gas (RNG) requires large-scale to be economically viable. Centralized manure AD-to-RNG systems can enable dairy farms of all sizes to collectively participate, including those who may not have the capital or land resources to build and operate their own AD system. One possible arrangement is to feed a single AD system with manure from multiple farms and upgrade biogas to RNG at the AD site. There are several factors to consider when planning for a centralized AD system for multiple farms; many are discussed in this fact sheet by Dairy Environmental Systems.
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    Considerations for central biogas upgrading to renewable natural gas from anaerobic digestion on multiple dairy farms
    George, Angela; Oliver, Jason; Ray, Lauren (PRO-DAIRY, 2023-03)
    Anaerobic digestion (AD) of dairy manure to produce renewable natural gas (RNG) requires large-scale to be economically viable. Centralized AD-to-RNG systems can enable multiple farms to collectively participate. One possible arrangement is to use a central biogas upgrading skid to upgrade biogas from multiple farms. This allows multiple farms with their own AD systems to convert biogas to RNG by sharing the cost of the RNG upgrading equipment and pipeline insertion point. There are several factors to consider when planning a centralized system; many are discussed in this fact sheet from Dairy Environmental Systems.
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    California Low Carbon Fuel Standard Carbon Intensity applied to New York State Dairy Manure Anaerobic Digestion to Renewable Natural Gas
    Ray, Lauren; Wright, Peter (2023-02)
    The information provided in this analysis report of California’s Low Carbon Fuel Standard (CA LCFS) Carbon Intensity (CI) score applied to biomethane or renewable natural gas (RNG) produced from dairy manure anaerobic digestion (AD) located on a New York (NY) State dairy farm can be used to understand the different CI score components and relative importance of them, as well as the opportunities to improve the score, total greenhouse gas (GHG) reduction, and revenue from CA LCFS credits and from RINs under the U.S. EPA Renewable Fuel Standard (RFS). An example NY dairy AD-to-RNG project CI score is computed using the CA LCFS Tier 1 CI Calculator and six different project scenarios are compared, including options to use part of the AD biogas for digester heating and to cover the digested effluent long-term storage. While the CI score under the CA LCFS program uses a 100-year global warming potential (GWP) for GHGs, a comparison of the total GHG reduction of the example project using the NY-adopted 20-year GWP is given in the summary.
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    Covered manure storage calculator
    Shepherd, Timothy; Karszes, Jason; Gooch, Curt (PRO-DAIRY, 2008-12-20)
    The dairy manure storage cost calculator help farms perform a partial budget of an impermeable flexible cover and flare on their dairy farm system. The farm inputs needed include the number of cows and heifers whose manure go into the storage, the surface area of the storage, and the farms manure spreading costs. The water excluded from the storage can be estimated for NYS by determining the average annual precipitation and subtracting the average annual evaporation shown on the illustration included. The current cover and flare costs will need to be estimated. An interest rate and cover life can be chosen and entered. If a grant will be used a negative additional capital cost can be entered. If carbon credits are anticipated the calculator will estimate the metric tons of carbon dioxide eq that can be captured and combusted. The calculation will provide the estimated total capital cost, the average annual cost over the lifetime, the annual average precipitation avoided, the average annual land application savings as well as an estimate of the potential carbon credits. There may be an additional benefit from nitrogen savings under the cover and protection from extreme rain events. Annual O&M costs for the cover and flare or for the verification of carbon credits are not considered.
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    Economic Feasibility Case Study of Co-Digestion of Manure and Food Waste on a Northern NY Dairy
    George, Angela; Ray, Lauren; Wright, Peter (2023-01)
    A case study of the economic feasibility of anaerobic digestion of dairy manure and food waste (co-digestion) on a Northern New York dairy farm was conducted that considered two scenarios. Scenario One analyzed the use of the farm's existing anaerobic digester to electricity system processing manure from it's herd of 1,860 lactating cow equivalents to take in a local source of cheese whey in a ratio of 20% by volume in the digester. Scenario Two analyzed the economic feasibility of a new anaerobic co-digestion system at the same size and location dairy farm that would take in 50% by volume of mixed food waste from local food and beverage manufacturers with the dairy's manure. Scenario Two included biogas upgrading to renewable natural gas (RNG) or biomethane for injection into the adjacent utility gas pipeline and sale to a third party. Net present value and the benefit-to-cost ratio are presented with the detailed capital and operating costs and benefits for each scenario.
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    Do’s and Don’ts for Barn Snow Removal
    Gooch, Curt; Steinberg, Sam (PRO-DAIRY, 2014-11-21)
    Removal of significant snow accumulations off of a barn roof is best performed in a systematic way to reduce the risk of injury or death to both barn occupants and those working on the roof. Removing roof snow without a proper approach may cause more damage than if left alone in some cases by creating an unbalanced and/or concentrated roof loads.
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    Centralized Systems for Anaerobic Digestion to Renewable Natural Gas
    George, Angela; Ray, Lauren (2022-09)
    Anaerobic digestion of dairy manure can be configured in various centralized systems involving multiple farms to achieve economy of scale for renewable natural gas (RNG), also known as biomethane, energy production. An overview of 3 configurations including aggregated manure to a central digester and aggregated biogas to centralized RNG upgrading are illustrated in this fact sheet. The key considerations and questions for discussion among participating dairy farms and the project developer are listed for these configurations.
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    Anaerobic Digestion at Greenwood Dairy: Case Study
    George, Angela (2022-06)
    A case study of Greenwood Dairy's manure anaerobic digestion to electricity system located in Canton, NY. The complete mix mesophilic digester was installed in 2014 and the biogas is utilized onsite to produce electricity using an engine-generator set. The electricity supplies the farm's needs and also some utility grid export through net metering. Waste heat from the engine is captured for heating the digester.