DOI: 10.5061/dryad.ht76hdrtc
title: Data from: Anaerobic digester installation significantly reduces liquid manure management CH<sub>4</sub> emissions at a California dairy farm

description: Anaerobic digesters are expected to significantly reduce CH4 emissions
 from dairy manure management by capturing them for use as biogas. However,
 verification of the effectiveness of anaerobic digesters to reduce CH4
 emissions has not been conducted at scale in California. We made
 atmospheric measurements from a mobile platform and used dispersion
 modeling to estimate CH4 emissions from a liquid manure storage complex at
 a typical California dairy before and after digester installation across
 nine field campaigns. We also compared measured emissions reduction to
 estimates using California Air Resources Board (CARB) inventory
 methodologies and estimated the statewide impact of emissions reduction by
 upscaling to planned or completed digester projects. This dataset contains
 the raw and processed files associated with the results of this study.
 More details on methodology and the variable definitions can be found in
 the supporting information documents associated with the manuscript. The
 CH4 emissions results from dispersion modeling, normalizations, and
 relative emissions reduction are presented as well as the averaged CH4
 mole fraction and associated meterological data for stationary receptor
 measurements used as inputs to the dispersion model. Instantaneous and
 grid cell averaged CH4 mole fraction data is included for all measurement
 campaigns. The dataset also contains the calculations for CARB methodology
 comparisions and estimating statewide upscaling. Dairy facility
 information and coordinates have been removed from all files.
description: # Data from: Anaerobic digester installation significantly reduces liquid
 manure management CH~4~ emissions at a California dairy farm Dataset DOI:
 [10.5061/dryad.ht76hdrtc](10.5061/dryad.ht76hdrtc) ## Description of the
 data and file structure These are data files associated with the
 manuscript Rodriguez et al., 2025 "Anaerobic digester installation
 significantly reduces liquid manure management CH4 emissions at a
 California dairy farm" published in GCB: Bioenergy. All files have
 coordinates and dairy facility information removed to protect dairy
 identity and location. ## Files and variables ### File:
 CH4_Emissions_Results.csv **Description**: "CH4 Emissions
 Results" contains the data output of CH4 emissions from the liquid
 manure storage complex as estimated by dispersion modeling for each
 measurement campaign. This data is used for Figure 2 in the manuscript and
 Figure S5 in the Supporting Information document. **Variables** *
 Campaign: Time of measurement pre or post digester installation. *
 Month: Month of measurement * Year: Year of measurement * CH4: Methane
 emissions in units of kg CH4 per day * Low.CH4: The low end value of the
 95% confidence interval. * High.CH4: The high end value of the 95%
 confidence interval. * CH4.head: Methane emissions normalized by the total
 of number of animals on site. Units of kg CH4 per day per head. *
 Low.CH4.head: The low end value of the 95% confidence interval normalized
 by the total number of animals on site. * High.CH4.head: The high end
 value of the 95% confidence interval normalized by the total number of
 animals on site. * CH4.lactatingcow: Methane emissions normalized by the
 just the number of lactating cows on site. Units of kg CH4 per day per
 lactating cow * Low.CH4.lactatingcow: The low end value of the 95%
 confidence interval normalized by just the number of lactating cows on
 site. * High.CH4.lactatingcow: The high end value of the 95% confidence
 interval normalized by just the number of lactating cows on site. ###
 File: CH4_Emissions_Normalizations.xlsx **Description:** "CH4
 Emissions Normalizations" shows the calculations used to the
 normalize CH4 emissions from the liquid manure storage complex as
 estimated by dispersion modeling for each measurement campaign. The number
 of lactating cows is available for each campaign but the number for other
 animal classes is only available as an annual average. Cells with n/a
 value indicate that month is not applicable because these values use
 annual average. **Variables** * Campaign: Time of measurement pre or post
 digester installation. * Month: Month of measurement * Year: Year of
 measurement * Animal Class: Diary animal classification categories
 existing on dairy site. * AU: Animal unit. * AU heads: Total number of
 animal based on AU conversion. * CH4: Methane emissions in units of kg CH4
 per day * Low.CH4: The low end value of the 95% confidence interval. *
 High.CH4: The high end value of the 95% confidence interval. *
 CH4.head: Methane emissions normalized by the total of number of animals
 on site. Units of kg CH4 per day per head. * Low.CH4.head: The low end
 value of the 95% confidence interval normalized by the total number of
 animals on site. * High.CH4.head: The high end value of the 95% confidence
 interval normalized by the total number of animals on site. *
 CH4.lactatingcow: Methane emissions normalized by the just the number of
 lactating cows on site. Units of kg CH4 per day per lactating cow *
 Low.CH4.lactatingcow: The low end value of the 95% confidence interval
 normalized by just the number of lactating cows on site. *
 High.CH4.lactatingcow: The high end value of the 95% confidence interval
 normalized by just the number of lactating cows on site. * CH4.AU: Methane
 emissions normalized by animal unit. * Low.CH4.AU: The low end value of
 the 95% confidence interval normalized animal unit * High.CH4.AU: The high
 end value of the 95% confidence interval normalized by animal unit ###
 File: CH4_Emissions_Relative_Change_and_Uncertainty_Calculation.xlsx
 **Description:** "CH4 Emissions Relative Change and Uncertainty
 Calculation" shows the calculations for the percent relative change
 in methane emissions as a result of the digester installation by comparing
 paired measurement months. The uncertainty is calculated as the propagated
 error in the percent relative change calculation using the 95% confidence
 intervals. Calculation equations are given in the Supporting Information
 section 3.1. Cells with null value indicate cell is left intentionally
 blank as no data is necessary. **Variables** * Normalization: The type of
 mean CH4 emission normalization. Either none, normalized by total number
 of animal heads on site, normalized by total number of lactating cows on
 site, normalized by animal unit * Campaign: Time of measurement pre or
 post digester installation. * Month: Month of measurement * Year: Year of
 measurement * CH4: Mean measured CH4 emissions * Low.CH4: The low end
 value of the 95% confidence interval. * High.CH4: The high end value of
 the 95% confidence interval. * Low.Difference: The absolute value
 difference between the mean and the low end of the 95% confidence interval
 used to calculate uncertainty. * High.Difference: The absolute value
 difference between the mean and the high end of the 95% confidence
 interval used to calculate uncertainty. * Unit: Units for numerical data
 in "CH4", "Low.CH4", "High.CH4",
 "Low.Difference", "High Difference". * Years Compared:
 The year of the paired months compared for relative change calculation. *
 Percent Relative Change: The percent (%) decrease in methane emissions
 after digester installation comparing paired months. * Uncertainty: The
 percent (%) propagated error in the percent relative change calculation.
 ### File: All_Receptor_Meteorology_and_CH4_Mole_Fraction_Data.csv
 **Description:** "All Receptor Meteorology and CH4 Mole Fraction
 Data" is the averaged CH4 mole fraction and associated meteorology
 data for each receptor location at the liquid manure storage complex. This
 data serves as the input data used to estimate CH4 emissions via
 dispersion modeling. Coordinates are removed. Meteorology data was
 collected on site except for the June 2022 data is gathered from the
 Visalia Airport. Cells with n/a value indicate data was not measured or
 not recorded for that certain measurement campaign or time interval.
 **Variables** * Campaign: Time of measurement pre or post digester
 installation. * Month: Month of measurement * Year: Year of measurement *
 TIMESTAMP: End timestamp for receptor measurement for which data is
 averaged over. * CH4 ppm: Averaged methane mole fraction in ppm * z2: The
 measurement height of the mobile laboratory in meters. * Ubar: The mean
 wind speed in the horizontal direction in meters per second. * Wbar: The
 mean wind speed in the vertical direction in meters per second. * Tbar:
 The mean air temperature in degrees Celsius. * sigmau: The standard
 deviation of wind speed in the u direction (east-west) in meters per
 second. * sigmav: The standard deviation of wind speed in the v direction
 (north-south) in meters per second. * sigmaw: The standard deviation of
 the vertical wind speed in meters per second. * sigmaT: The standard
 deviation of the sonic measured air temperature in degrees Celsius. *
 WindDirection: The mean wind direction in radians. * WindDirectionDegrees:
 The mean wind direction in degrees. * sigmaWD: The standard deviation of
 the wind direction in radians. * HeatFlux: The heat energy transfer rate
 in Watts per square meter. * ustar: The friction velocity (a metric of
 turbulence) in meters per second. * MOLength: The Monin-Obukhov length, a
 unitless metric of atmospheric stability. * Uscalar: The mean wind speed
 not accounting for wind direction in meters per second. * n: The number of
 instantaneous measurements included in the time averaging. * zref: The
 height of the stationary sonic anemometer in meters. ### File:
 All_Instantaneous_Gridded_CH4_Mole_Fraction_Data.csv
 **Description:** "All Instantaneous Gridded CH4 Mole Fraction
 Data" shows all the CH4 mole fraction data collected in the afternoon
 receptor measurements at the liquid manure storage complex. This data is
 used for visualizing CH4 mole fractions in Figure 3. This data is also
 used for visualizing CH4 mole fractions on a grid of the liquid manure
 storage complex by relating coordinates (removed in this dataset) to grid
 cells as identified in figure S6 in the Supporting Information document.
 **Variables** * Campaign: Time of measurement pre or post digester
 installation. * Month: Month of measurement * Year: Year of measurement *
 TIMESTAMP: Timestamp of measurement in format of M/DD/YYYY h:mm:ss * CH4
 ppm: The instantaneous methane mole fraction. * Grid Cell: The grid cell
 location as visualized in Figure S6 in the Supporting Information
 document. ### File: CH4_Mole_Fraction_Grid_Cell_Summary.csv
 **Description:** "CH4 Mole Fraction Grid Cell Summary" shows the
 summarized statistics data for each individual grid cell as visualized in
 Figure 4 in the manuscript and Figures S7 and S8 in the Supporting
 Information document. Cells with n/a values indicate data is not available
 because cannot be calculated with n = 1 measurements. **Variables** *
 Campaign: Time of measurement pre or post digester installation. * Month:
 Month of measurement * Grid Cell: The grid cell location as visualized in
 Figure S6 in the Supporting Information document. * n: The number of
 instantaneous CH4 mole fraction measurements in a grid cell. * mean CH4
 ppm: The average of instantaneous CH4 mole fraction measurements in a grid
 cell. * sd CH4 ppm: The standard deviation of instantaneous CH4 mole
 fraction measurements in a grid cell. * se CH4 ppm: The standard error of
 instantaneous CH4 mole fraction measurements in a grid cell. Standard
 error is calculated as: se = (sd / n) ### File:
 CARB_Estimates_Comparison.xlsx **Description:** "CARB Estimates
 Comparison" shows the full calculation of annual average daily CH4
 emission rate from the liquid manure storage complex as estimated using
 two methods informed by methodology used by the California Air Resources
 Board. These methodology and all variables are further described in the
 methods section of the manuscript and in the Supporting Information
 document section 2.4. This file also shows the comparison between
 estimated emissions and emissions measured on site in this study. Cells
 with n/a value indicate there is not measured uncertainty in bottom-up
 calculation methods used by California Air Resources Board. ### File:
 Statewide_Upscaling_Dairy_Digesters.xlsx **Description:** "Statewide
 Upscaling Dairy Digesters" shows the calculation for estimating the
 statewide impact of covered lagoon anaerobic digesters in California. This
 data considers CH4 emissions from liquid manure storage only. 139 dairies
 were identified to have installed or plan to install covered lagoon
 anaerobic digesters as described in section 2.5 in the manuscript. Dairy
 locations and information was removed. For each dairy, annual facility
 baseline anaerobic lagoon CH4 emissions was estimated for each facility
 using methodology from Marklein et al., 2021. The facility level decrease
 in CH4 emissions from liquid manure storage (anaerobic lagoons) was
 estimated using the average decrease in CH4 emissions after digester
 installation normalized by the number of lactating cows (82% +/- 16%)
 measured in this study. The Total annual CH4 decrease due to digester
 installation was estimated as the sum of facility level decreases. All
 values are in units of gigagrams (Gg). **Variables** * Annual Facility
 Baseline Lagoon CH4 Emissions: Baseline methane emissions from anaerobic
 lagoon manure storage for each dairy facility using methodology from
 Marklein et al., 2021. Units of gigagrams (Gg) * Measured Annual Average
 CH4 Mitigation: The estimated decrease in anaerobic lagoon manure storage
 methane emissions (~82%) after covered lagoon anaerobic digester
 installation as measured in our study. * Uncertainty in Measured CH4
 Mitigation The estimated error in the Measured Annual Average CH4
 Mitigation (~16%) as estimated in our study. * Annual Facility CH4
 Mitigation due to Digester: The estimated decrease in anaerobic lagoon
 manure storage methane emissions for each dairy facility after covered
 lagoon anaerobic digester installation considering out Measured Annual
 Average CH4 Mitigation (~82%). Units of Gg (gigagrams). * Uncertainty in
 Estimated Mitigation: The estimated error in Annual Facility CH4
 Mitigation due to Digester considering our Uncertainty in Measured CH4
 Mitigation (~16%). Units of Gg (gigagrams).