there has been a “gold rush”-like fervor by project developers to sign up large dairy farms (>3,000 cows) near natural gas pipelines because of the profitability of projects that collect and scrub biogas and inject methane into the pipeline. The profitability driver is demand for low carbon intensity Renewable Natural Gas (RNG) to fuel commercial fleets that are converting from gas or diesel fuel to cleaner burning Compressed Natural Gas (CNG). Low carbon RNG is measured and rewarded through programs such as California’s Low Carbon Fuel Standard (LCFS) crediting program and the “stacking” of Federal Renewable Identification Numbers (RINs) assigned to the same volume of renewable fuel, courtesy of the Federal Renewable Fuel Standard (RFS) program. These environmental benefits are in addition to the price of natural gas which has been selling for $3 to $6/MMBtu. Both the state and federal government environmental markets require the sellers of transportation fuels to reduce the carbon intensity of the fuel they sell by varying amounts and time frames. This has resulted in impressive prices for LCFS credits and RINs because of the very low carbon intensity of RNG generated from cow manure. The California LCFS program has the highest price of all environmental programs. The price peaked at $199 per ton in 2020 and is currently at $65 per ton. The program is expected to be revised in 2023 to increase prices. However, there is legislation that could prohibit the sale of credits from dairy digesters into the California LCFS program, starting in 2024. At the same time, there is also the potential that these credits could be sold into the Oregon or Washington clean fuel programs that are in the early stages of development. Gross revenue from RNG projects on dairy farms has been as high as $2,300/cow/year, but farmers are typically receiving less than 10 percent of that amount because they aren’t the project developers and don’t contribute capital to the multimillion dollar projects. Farmers who are being courted by project developers are advised to work with experts to help them find and secure the best deal.
and digester development. Adding biochar, acids, and straw to lagoons can reduce CH4 emissions by 82.4 percent, 78.1 percent, and 47.7 percent, respectively. 5 However, these practices are not being widely adopted because their use adds cost with no payback potential. And most importantly, reducing CH4 emissions at dairy farms (outside of California), isn’t required by regulations and there is no incentive to do so because there is no revenue generation potential from creating carbon credits. Why? Because no approved protocol exists likely because the emissions reductions are very difficult to measure in commercial settings. Compost additives: Composting manure requires maintaining a carbon to nitrogen (C:N) ratio of about 30:1. Manure is high in nitrogen and low in carbon. To reach a C:N ratio of 30:1 requires the addition of bulking agents to increase the carbon and solids content. Typical additives include straw, sawdust, hay, and leaves. Composting is most appropriate for producers with dry manure handling systems or those using solid-liquid separation. Unfortunately, the composting of manure requires significant time, equipment, and costs that do not yield a return from the sale of the manure. Manure management: Several practices have been identified that can reduce emissions between 0.2 tons and almost six tons of GHG emissions per cow per year. Currently, California is the only state that financially rewards the implementation of these practices through state-funded programs. Other states, as well as supply chain companies, could leverage some of the tools and processes being used in California to provide incentives for dairies. The practices include:
— Alternative manure treatment and storage practices, such as the installation of composting facilities.
— Separation of manure solids prior to entry into a lagoon, settling pond, or settling basin by installing technology, such as a stationary screen, screw press, centrifuge, or roller drum.
Lagoon additives: Leading dairy scientists have found that additives to manure lagoons are an available method to reduce CH4 emissions compared to technology such as solids separation
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