Russell McGee

Determining Seasonal Greenhouse Gas Emissions from Ground-Level Area Sources in a Dairy Operation in Central Texas

ABSTRACT Greenhouse gas (GHG) emissions from agricultural production operations are recognized as an important air quality issue. A new technique following the U.S. Environmental Protection Agency Method TO-14A was used to measure GHG emissions from ground-level area sources (GLAS) in a free-stall dairy operation in central Texas. The objective of this study was to quantify and report GHG emission rates (ERs) from the dairy during the summer and winter using this protocol. A weeklong sampling was performed during each season. A total of 75 and 66 chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin, and lagoon) of the same dairy during summer and winter, respectively. Three primary GHGs—methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O)—were identified from the dairy operation during the sampling periods. The estimated overall ERs for CH4, CO2, and N2O during the summer for this dairy were 274, 6005, and 7.96 g head−1day−1, respectively. During the winter, the estimated overall CH4, CO2, and N2O ERs were 52, 7471, and 3.59 g head−1day−1, respectively. The overall CH4 and N2O ERs during the summer were approximately 5.3 and 2.2 times higher than those in the winter for the free-stall dairy. These seasonal variations were likely due to fluctuations in ambient temperature, dairy manure loading rates, and manure microbial activity of GLAS. The annualized ERs for CH4, CO2, and N2O for this dairy were estimated to be 181, 6612, and 6.13 g head−1day−1, respectively. Total GHG emissions calculated for this dairy with 500 cows were 2250 t of carbon dioxide equivalent (CO2e) per year. IMPLICATIONS The agricultural sector, especially concentrated animal feeding operations (CAFOs) contribute a considerable amount of GHGs to the atmosphere. To develop abatement strategies to reduce GHG emissions, it is important to learn to collect, analyze, verify, and report real data on actual emissions. Therefore, there is a need for a robust and accurate technique/protocol to measure GHGs from CAFOs. It is important to obtain direct estimates of GHG emissions from different GLAS in CAFOs to compile emission inventories and to develop GLAS-specific abatement strategies.

Comparison of seasonal phenol and p-cresol emissions from ground-level area sources in a dairy operation in central Texas

Although there are more than 200 odor-causing volatile organic compounds (VOCs), phenol and p-cresol are two prominent odor-causing VOCs found downwind from concentrated animal feeding operations (CAFOs). The VOC emissions from cattle and dairy production are difficult to quantify accurately because of their low concentrations, spatial variability, and limitations of available instruments. To quantify VOCs, a protocol following U.S. Environmental Protection Agency (EPA) Method TO-14A has been established based on the isolation flux chamber method and a portable gas chromatograph (GC) coupled with a purge-and-trap system. The general objective of this research was to quantify phenol and p-cresol emission rates (ERs) from different ground-level area sources (GLASs) in a free-stall dairy during summer and winter seasons using this protocol. Two-week-long sampling campaigns were conducted in a dairy operation in central Texas. Twenty-nine air samples were collected during winter and 37 samples were collected during summer from six specifically delineated GLASs (barn, loafing pen, lagoon, settling basin, silage pile, and walkway) at the free-stall dairy. Thirteen VOCs were identified during the sampling period and the GC was calibrated for phenol and p-cresol, the primary odorous VOCs identified. The overall calculated ERs for phenol and p-cresol were 2656 ± 728 and 763 ± 212 mg hd−1 day−1, respectively, during winter. Overall phenol and p-cresol ERs were calculated to be 1183 ± 361 and 551 ± 214 mg hd−1 day−1, respectively, during summer. In general, overall phenol and p-cresol ERs during winter were about 2.3 and 1.4 times, respectively, higher than those during summer. Implications: Concentrated animal feeding operations contribute a considerable amount of VOCs to the atmosphere. The phenol and p-cresol are two VOCs recognized as potential odor-causing compounds emitted from livestock operation. To develop effective strategies for mitigating livestock odorous VOC emissions, relative emissions from different GLAS in a livestock operation under different climate conditions should be quantified. It is also important to obtain direct estimates of VOC emissions from different GLAS in CAFOs to compile emission inventories. This research determined phenol and p-cresol emissions from different GLAS in a free-stall dairy and also identified areas in a dairy operations that have the highest phenol and p-cresol emissions.

Evaluation and Modeling of PM10 Emissions from Laying Hen Operations

The emission rates of particulate matter emitted from cattle feedyards, dairies, cotton gins, and grain elevators are regulated by the SAPRAs. The goal of this research was to develop emission factors and emission rates for PM10 emitted at laying hen operations, and to determine the property line distances for the facility to maintain compliance with the NAAQS. PM10 concentrations inside a laying hen operation were measured by Wang et al. in North Carolina, using TEOM and filter-based low-volume PM10 samplers. Thirty-minute measurements were collected by TEOM samplers and 24-hour measurements were collected using gravimetric samplers. Flow rates required for ventilation at the facility were considered for four different scenarios in order to obtain the emission rates and emission factors of PM10. The PM10 and PM2.5 emission factors were higher and the TSP emission factors were lower in laying hen operations than broiler operations. Emission factors were used in AERMOD to obtain 24-hour average PM10 concentrations emitted from the facility. Consequently, the property line distances at which the emissions of PM10 were below the 24-hour average PM10 standards, were estimated. The results indicated that the laying hen facility required substantially large property line distances, when the fans provided for ventilation purposes were assumed to be running at all times. Property line distances were smaller, on accounting for the over-sampling of PM10 pre-collectors and the minimum flow rate recommendations by the Midwest Plan Service.

Benefits of Onsite Gasification of Cotton Gin Trash for Power Production at Cotton Gins

The decision by the EPA to regulate green house gases (GHG) and to significantly reduce GHG emissions from coal fired power plants (CFPP), will likely result in reduced availability of electricity in the near future. The technology exists to produce electricity from power plants fueled with cotton gin trash (CGT). The utilization of excess cotton biomass (CGT) as the fuel to produce useable energy with a gasification-based conversion technology is not new. Cotton gins will realize immediate benefits from the use of CGT to fuel on-site power plants through gasification. Gins will become a source of reliable electricity and heat energy during the ginning season and beyond. The expense of CGT disposal will be eliminated and replaced with additional revenue streams from the gasification process. Biochar produced as a byproduct of gasification may be sold as a commodity or value-added product. Excess electricity produced at the gin can be sold back to the grid to generate additional revenue. Renewable energy benefits may result in additional savings and benefits. Credits for green energy and carbon sequestration may also contribute to the cotton gin’s revenue stream.

Comparison of Greenhouse Gas Emissions from Ground Level Area Sources in Dairy and Cattle Feedyard Operations

A protocol that consisted of an isolation flux chamber and a portable gas chromatograph was used to directly quantify greenhouse gas (GHG) emissions at a dairy and a feedyard operation in the Texas Panhandle. Field sampling campaigns were performed 5 days in a week during daylight hours from 9:00 to 7:00 pm each day. The objective of this research was to quantify and compare GHG emission rates (ERs) from ground level area sources (GLAS) at dairy and cattle feedyard operations during the summer. A total of 74 air samples using flux chamber were collected from the barn (manure lane and bedding area), loafing pen, open lot, settling basin, lagoons, and compost pile within the dairy operation. For the cattle feedyard, a total of 87 air samples were collected from four corner pens of a large feedlot, runoff holding pond, and compost pile. Three primary GHGs (methane, carbon dioxide, and nitrous oxide) were measured and quantified from both operations. The aggregate estimated ERs for CH4, CO2, and N2O were 836, 5,573, 3.4 g hd-1d-1 (collectively 27.5 kg carbon dioxide equivalent (CO2e) hd-1 d-1), respectively, at the dairy operation. The aggregate ERs for CH4, CO2, and N2O were 3.8, 1,399, 0.68 g hd-1d-1 (1.7 kg CO2e hd-1 d-1), respectively, from the feedyard. Aggregate CH4, CO2, and N2O ERs at the dairy facility were about 219, 4 and 5 times higher, respectively, than those at the feedyard.

Measurements of Volatile Organic Compounds from Ground Level Area Sources in a Dairy Operation using Isolation Flux Chamber

Phenol and p-cresol were the most abundant and persistent odor-causing volatile organic compounds (VOCs) found downwind from concentrated animal feeding operations (CAFOs), while more than 200 VOCs contribute to odor. The VOC emissions from cattle and dairy production are difficult to quantify accurately because of their low concentrations, spatial variability, and the lack of appropriate instruments. To quantify two odorous VOCs, a new protocol similar to EPA method TO-14A, has been established based on the isolation flux chamber method and the use of portable gas chromatographs coupled with a purge and trap system. The objective of this research was to quantify and report phenol and p-cresol emission factors (EFs) from different ground level area sources (GLASs) in a free-stall dairy using the new protocol. Two week-long samplings were conducted in a dairy operation in Central Texas during winter and summer. Twenty nine and 37 samples were collected from six-specifically delineated GLAS (barn, loafing pen, lagoon, settling basin, silage pile, and walkway) in a free-stall dairy during the winter and summer. Thirteen VOCs were identified from a dairy operation during the sampling period, and the gas chromatograph (GC) was calibrated for phenol and p-cresol, the primary compounds found. The overall calculated EFs for phenol and p-cresol were 0.97±0.27 and 0.28±0.08 kg hd-1 yr-1, respectively, in winter. Overall calculated phenol and p-cresol EFs were 0.43±0.13 and 0.2±0.08 kg hd-1 yr-1, respectively, during summer. Overall phenol and p-cresol EFs in the winter were about 2.3 and 1.4 times, respectively, higher than those during the summer.

Direct Measurements of Greenhouse Gas Emissions from Ground Level Area Sources in a Dairy Operation

A new protocol similar to EPA method TO-14A was used to quantify and report variations in greenhouse (GHG) emissions from different ground level area sources (GLAS) in a free-stall dairy in central Texas during summer and winter. A week-long sampling was performed during each season. Seventy five and 66 chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin and lagoon) of the same dairy during summer and winter, respectively. Three primary GHGs were identified from the dairy operation during sampling period and the gas chromatograph (GC) was calibrated for methane (CH4), carbon dioxide (CO2), and nitrous oxide N2O. Estimated overall emission factors (EFs) for CH4, CO2 and N2O during summer for this dairy were, 100, 2192, 2.9 kg hd-1 yr-1, respectively. In winter, estimated overall EFs for CH4, CO2 and N2O for this dairy were, 19, 2726, 1.3 kg hd-1 yr-1, respectively. Overall CH4 and N2O EFs in summer were about 5.2 and 2.2 times higher than those in winter for this free-stall dairy. This seasonal variation was due to ambient temperature, dairy waste loading rates, and manure microbial activity of GLAS.

Measurements of Volatile Organic Compound and Greenhouse Gas Emissions from Ground Level Area Sources in a Beef Feedyard using Isolation Flux Chamber

A new protocol similar to EPA method TO-14A was used to quantify and report variations in odorous volatile organic compound (VOC) and greenhouse gas (GHG) emissions from different ground level area sources (GLAS) namely feedlot, compost piles and lagoon in a beef feedyard in Texas Panhandle. The objective of this study was to measure gas concentrations and estimate emission factors (EFs) of phenol, p-cresol, methane (CH4), and carbon dioxide (CO2) from this beef feedyard operation. A week-long sampling was conducted and a total of 46 VOCs and 83 GHGs were sampled simultaneously from different GLAS. Thirteen VOCs were identified during sampling period and the gas chromatograph (GC) was calibrated for phenol and p-cresol, the primary compounds found. The GHG GC was calibrated for CH4, CO2, and nitrous oxide (N2O). In the beef feedyard, average measured concentrations of phenol and p-cresol in four corners of the feedlot ranged from 56 to 300 ppbv and 14 to 76 ppbv, respectively. Measured average concentrations for CH4 and CO2 in four pens ranged from 3.6 to 39.6 ppmv and 561 to 626 ppmv, respectively. Average phenol EFs were 0.131±0.111, 0.005±0.002, and 0.001±0.000 kg hd-1 yr-1 from feedlot, compost piles, and lagoon, respectively. Estimated average p-cresol EFs were 0.045±0.036, 0.002±0.001, and 0.0002±0.00004 kg hd-1 yr-1 from feedlot, compost piles, and lagoon, respectively. The overall estimated EFs for phenol and p-cresol were 0.137±0.113 and 0.047±0.037 kg hd-1 yr-1, respectively, during summer. The feedlot alone contributed about 95% of the overall phenol and p-cresol emissions for this feedyard. The overall estimated CH4 and CO2 EFs were 2.18±2.98 and 386±157 kg hd-1 yr-1, respectively. During summer, the feedlot alone contributed about 73% and 82% of the overall CH4 and CO2 emissions from this feedyard.

Greenhouse Gas Emissions from Ground Level Area Sources in a Dairy Operation

A new protocol similar to EPA method TO-14A was established to quantify and report variations in greenhouse gas (GHG) emissions from different ground level area sources (GLAS) in a free-stall dairy in central Texas. The objective of the study was to estimate and compare methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emission factors (EFs) from different GLAS using this new protocol during summer. A week-long sampling was performed during summer and seventy five chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin and lagoon) of the same dairy. Three primary GHGs were identified from the dairy operation during sampling period and the gas chromatograph (GC) was calibrated for CH4, CO2, and N2O. The GHGs concentrations measured at different GLAS during summer were ranged from 4.04±3.4 to 2493±1298, 383±131 to 3107±3878, and 0.06±0.03 to 1.6±2.0 ppmv for CH4, CO2, and N2O, respectively. These variations in measured gas concentrations within each GLAS were widely varied due to spatially variable manure loading rates at different GLAS in a dairy operation. Average CH4, CO2 and N2O EFs estimated from different GLAS were ranged from 0.10 to 60.5, 21 to 1767, and 0.002 to 2.73 kg hd-1 yr-1, respectively, during summer. Estimated overall EFs for CH4, CO2 and N2O during summer for this dairy were, 100±56, 2192±1510, 2.9±3.5 kg hd-1 yr-1, respectively.