John W. Earnest

Use of CO2 Concentration Difference or CO2 Balance to Assess Ventilation Rate of Broiler Houses

Ventilation rate (VR) is one of the two key elements for quantifying aerial emissions from animal production facilities. Direct, continuous measurement of building VR can be challenging and impractical under certain circumstances, e.g., naturally ventilated animal housing or a large number of ventilation fans in the building. This study examined the suitability of estimating VR of broiler houses with built-up litter (mixture of manure and bedding), when supplemental heating was not in use, through either carbon dioxide (CO 2 ) balance or the relationship of VR to CO 2 concentration difference between exhaust and inlet air. The reference VR was based on direct measurement by continuously monitoring operation of the in-situ calibrated exhaust fans. The comparative analysis of the direct method vs. each indirect method was conducted for a measurement integration time (MIT) of 10, 30, 60, or 120 min. The analyses revealed that MIT of 30 min or greater resulted in non-significant differences in VR between the indirect and direct methods. The broiler building VR (m 3 s -1 ) may be related to the exhaust-inlet CO 2 concentration difference (ΔCO 2 , ppm) as VR (±3.0) = 4456 (±41) ΔCO 2 -0.786 (±0.019) at 30 min MIT. The VR may also be determined by the CO 2 balance method (including litter CO 2 generation) with a correction factor of 0.97 at MIT of 30 to 120 min. If litter CO 2 generation is omitted from the total building CO 2 production, the actual VR may be estimated by applying a correction factor of 1.077 to the bird respiration CO 2 balance VR. Hence, the CO 2 balance or concentration difference method offers a viable alternative or supplemental check for quantifying building VR under certain conditions where direct, continuous VR measurement is not feasible.

Ammonia Emissions from Broiler Houses in the Southeastern United States

Continuous monitoring of ammonia (NH3) emissions from two mechanically ventilated commercial broiler houses located in the southeastern United States was performed during a one-year period over 2005-2006 as a joint effort between Iowa State University and the University of Kentucky. Ammonia concentrations were measured using Innova 1412 photoacoustic NH3 monitors. Ventilation rates in each house were measured continuously by monitoring the building static pressure and operational status of all ventilation fans in conjunction with individual performance curves developed and verified in situ using a Fan Assessment Numeration System (FANS) unit. Expressed in various units, NH3 emissions from the two broiler houses over the one-year production period were of the following values: a) 35.4 g per bird marketed (77.9 lb per 1,000 birds marketed), including both grow-out (50-54 d per flock) and downtime (12-25 d between flocks) emissions; b) annual (365-d) emission of 4.63 Mg (5.1 US tons) per house, including both grow-outs and downtime; c) maximum grow-out daily emission of 30.6 kg/d-house (67.4 lb/d-house) for one house and 35.5 kg/d-house (78.2 lb/d-house) for the other; d) mean grow-out daily emission of 14.0 ± 9.1 ( S.D.) kg/d-house; e) mean downtime daily emission of 8.8 ± 8.3 kg/d-house. Flocks on new bedding had a lower emission rate of 12.4 ± 9.4 kg/d-house, as compared to 14.5 ± 8.9 kg/d-house for flocks on built-up litter. The NH3 emission factor of 35.4 g/bird marketed from this study is substantially lower than that cited by US EPA of 100 g/yr-bird (the US EPA yr-bird unit is equivalent to bird marketed).

Quantification of Particulate Emissions from Broiler Houses in the Southeastern United States

Emissions of total suspended particulate (TSP), particulate matter with aerodynamic diameters = 10 µm (PM10), and = 2.5 µm (PM2.5) were continuously monitored at two mechanically ventilated broiler houses in the southeastern United States. Monitoring was performed over a one-year period during 2005-2006 as a joint effort between Iowa State University and the University of Kentucky. Tapered Element Oscillating Microbalances (TEOMs) were used to measure three species of particulate matter (TSP, PM10 and PM2.5). Ventilation rates were measured continuously by monitoring building static pressure and operational status of ventilation fans in conjunction with individual performance curves developed and verified in situ using a Fan Assessment Numeration System (FANS) unit. The magnitude of the TSP, PM10 and PM2.5 emissions are reported as a) annual house total emission and b) on a per 1,000 birds marketed basis. These emission values are: a) 785 kg (1,731 lb) TSP, 330 kg (727 lb) PM10, and 32.5 kg (71.7 lb) PM2.5 per house per year and b) 6.03 kg (13.3 lb) TSP, 2.52 kg (5.56 lb) PM10, and 0.25 kg (0.55 lb) PM2.5, per 1,000 birds marketed. Bird age is the predominant factor influencing particulate emissions. An empirical equation is presented that relates emissions to bird age for the monitored broiler houses. The use of a daily emission factor is not advised for broiler production systems or others in which substantial progressive animal growth occurs over time. The use of emissions per 1,000 birds marketed more realistically expresses emissions and allows for improved emissions inventory tracking.

Greenhouse Gas (GHG) Emissions from Broiler Houses in the Southeastern United States

Greenhouse gas (GHG) emissions, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), from broiler houses located in the southeastern United States were continuously monitored over a one-year period. The birds were grown to 52 days of age at an average stocking density of 11.8 birds/m2 (1.1 birds/ft2). Methane and CO2 emissions were measured in two broiler houses while N2O emissions were measured in one house. Carbon dioxide and N2O concentrations were measured using a photoacoustic multi-gas analyzer and CH4 concentrations were measured using a dual-channel methane/non-methane-hydrocarbon (NMHC)/total hydrocarbon analyzer with dual flame ionization detectors. Ventilation rates in each house were continuously calculated by monitoring the building static pressure and operational status of all ventilation fans in conjunction with individual fan performance curves developed and verified in situ using a Fan Assessment Numeration System (FANS) unit. Annual CO2 emissions measured from the two broiler houses averaged 606 Mg (668 US tons) per house. On a marketed bird basis the CO2 emissions averaged 4.64 Mg (5.49 US tons) per 1,000 birds marketed. Annual CH4 emissions averaged 445 kg (982 lbs) per house, or 3.41 kg (7.52 lbs) per 1,000 birds marketed. Annual N2O emissions measured from one broiler house was 225 kg (496 lbs) per house, or 1.72 kg (3.8 lbs) per 1,000 birds marketed. The CO2 equivalents of the CH4 and N2O emissions were, respectively, 85.3 kg (188 lb) and 512.6 kg (1,128 lb) per 1,000 birds marketed. Hence the total CO2 equivalent GHG emissions for the broiler operations monitored in this study were 5.238 Mg per 1,000 birds marketed, with 88.6% contributed by CO2.

Comparison between two systems for ammonia emission monitoring in broiler houses

This work aimed to compare two systems used for ammonia emission monitoring in broiler houses. The low cost PMU (Portable Monitoring Unit), and MAEMU (Mobile Air Emission Monitoring Unit) are systems used for ammonia concentration monitoring and, with broiler house ventilation rate, ammonia emission rate (ER) can be calculated. The accuracy of ammonia emission rate calculated with data from the PMU using a simplified calculation algorithm was quantified using the MAEMU as a standard.

Use of CO2 Concentrations or CO2 Balance to Estimate Ventilation Rate of Modern Commercial Broiler Houses

Ventilation rate (VR) is one of the two key elements for quantifying aerial emissions from animal production facilities. Direct measurement of building VR can be challenging and impractical under certain circumstances, e.g., naturally ventilated animal housing. This study delineates VR of broiler houses with build-up litter as estimated via CO2 balance or building CO2 concentration. The indirectly derived VR compared favorably with the directly measured VR. Specifically, integration time of 30 min or longer leads to non-significant differences in VR between the indirect and the direct methods (P>0.2). Omission of CO2 generation by the litter from total house CO2 production results in an overall 7% underestimation of the building VR. The indirect method provides a possible, viable alternative for quantifying VR of naturally ventilated broiler confinement.

Hydrogen Sulfide and Nonmethane Hydrocarbon Emissions from Broiler Houses in the Southeastern United States

Hydrogen sulfide (H2S) and nonmethane hydrocarbon (NMHC) emissions from two mechanically ventilated commercial broiler houses located in the southeastern United States were continuously monitored over 12 flocks for a one-year period during 2006-2007 as a joint effort between Iowa State University and the University of Kentucky. H2S and NMHC concentrations were measured using UV-Fluorescence H2S analyzers and methane/nonmethane/total hydrocarbon dual flame ionization detector gas chromatographs. Ventilation rates in each house were measured continuously by monitoring building static pressure and operational status of all ventilation fans in conjunction with individual performance curves developed and verified in situ using a Fan Assessment Numeration System (FANS) unit. United States EPA methods TO-15 and TO-17 were used for the nonmethane hydrocarbon compound speciation. The top-25 compounds are presented. The overall mean H2S and NMHC emission rates for a one-year period were 65.7 ± 42 g/d-house and 0.76 ± 0.43 kg C3H8/d-house, respectively. Annual H2S emission for the two broiler houses (including downtime emissions) averaged 19.2 kg per year per house or 0.147 g per bird marketed when the birds were marketed at 52 days of age with a stocking density of 11.8 bird per m2 (1.1 bird per ft2). Annual NMHC emission averaged 231 kg per year per house (510 lb per year per house) or 1.77 g per bird marketed.

Assessing Air Leakage in Commercial Broiler Houses

The design and operation of broiler house ventilation are directly related to the air inlet characteristics. Air leakage affects the air distribution and mixing inside the houses causing negative effects on the inside air quality and environmental control. A common method of evaluating broiler house tightness is to entirely close the house, turn on a single 1.2m (48-inch) exhaust fan, and record the static pressure. A new procedure to assess broiler house tightness was developed. Fourteen air leakage curves (of the form **this equation is following the Introduction below***) from fourteen different broiler houses (located in the state of Kentucky) were developed by recording static pressure inside the house when different calibrated fans were turned on. A Fan Assessment Numeration System (FANS) was used for exhaust fan calibration. The air flow exponent (n) ranged from 0.35 to 0.74 (standard error varying from 0.02 to 0.12). The flow coefficient k (m3s-1Pa-n) ranged from 0.55 to 3.55 (standard error varying from 0.1 to 0.45). The results show substantial variability among Kentucky broiler houses.

Calibration Drift Assessment and Upgrades to the Fan Assessment Numeration System (FANS)

Aerial emissions from animal feeding operations have been a growing concern for rural residents in the U.S. In order to accurately quantify emissions from a livestock facility, the ventilation rates of each fan operating at a facility are needed. One means of providing this information is to create an in-situ calibration for each fan. The original Fans Assessment Numeration System (FANS) was developed for this purpose. Since the first generation FANS units were released major improvements have been made to improve their efficiency and reliability. The purpose of this paper is to outline the new enhancements made to the fourth generation (G4) FANS units and compare the performance of the fourth generation to its predecessors. The most recent updates included a faster travel rate, sealed limit switches, and an adjustable chain tensioning mechanism. In addition to the hardware updates on each of the new units, the FANS software was updated to include Bluetooth wireless connection capabilities, real-time anemometer RPM and estimated ventilation rate readouts. Four newly manufactured G4 FANS units were calibrated and compared to previous generations of the FANS units. A calibration drift assessment was also performed on select individual FANS units over a ten-year period, which found the absolute accuracy of the FANS units do not fluctuate over time unless there are mechanical malfunctions occurring within the FANS device.