Carbon footprint of poultry production farms in South Georgia: A case study

Transcription

1 C 2015 Poultry Science Association, Inc. Carbon footprint of poultry production farms in South Georgia: A case study C. S. Dunkley, 1 B. D. Fairchild, C. W. Ritz, B. H. Kiepper, and M. P. Lacy Department of Poultry Science, University of Georgia, Athens, GA Primary Audience: Climate Change, Environmental Managers of Poultry Companies SUMMARY A study was conducted in South Georgia to assess the carbon footprint of poultry farms. The study included broiler grow-out farms, pullet farms, and breeder farms from one commercial broiler complex. Data collection included the fuel and electricity bills from each farm, house size and age, flock size and number of flocks per year, and manure management. Emissions were calculated using a greenhouse gas (GHG) calculation tool. The carbon dioxide, nitrous oxide, and methane (CH 4 ) emissions were computed and a carbon footprint determined. Carbon footprint comparisons were made based on house construction and age. Based on these results, an evaluation of the mechanical sources of emissions showed that approximately 96% of the emissions from the broiler and pullet farms were from propane use, while only 3.9% of the total mechanical emissions from breeder farms were from propane use. On breeder farms, 83% of mechanical GHG emissions were the result of electricity use, while the pullet and broiler grow-out farms accounted for 2.9 and 2.7%, respectively, of the total mechanical emissions from electricity use. The data collected from the farms and entered into the GHG calculation tool revealed that breeder houses had higher levels of CH 4 emissions from manure management when compared to emissions from broiler and pullet houses. Even though the GHG emissions from poultry production farms were minimal compared to other animal production farms, the different sources of emissions were identified, thereby enabling the farmer to target specific areas for mitigation. Key words: greenhouse gas, poultry farms, carbon footprint 2015 J. Appl. Poult. Res. 24: INTRODUCTION The Consolidated Appropriations Act of 2008 included a provision that directed the United States Environmental Protection Agency (EPA) to require mandatory reporting of greenhouse gasses (GHG) emissions from relevant sources in all sectors in the US economy [1]. Human activities, including modern agriculture, contribute to GHG emissions [2]. GHGs are defined by their radiative forces (defined as the change 1 Corresponding author: cdunkley@uga.edu in net irradiance at atmospheric boundaries between different layers of the atmosphere), which change the Earth s atmospheric energy balance [2]. These gases can prevent heat from radiating or reflecting away from the Earth and thus may result in atmospheric warming. A 1996 report published by the Intergovernmental Panel on Climate Change [2] revealed that GHG levels have increased since the Industrial Revolution. This was a period from the 18th to the 19th centuries when manufacturing began to rely on steam power (primarily coal) rather than animal, wind, or water power. The GHGs

2 74 JAPR: Research Report that are of particular concern include carbon dioxide (CO 2 ), nitrous oxide (N 2 O), methane (CH 4 ), hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF 6 ). Agricultural activities are significant producers of N 2 OandCH 4, which are of primary concern because they occur naturally in agriculture, while other emissions (excluding CO 2 ), such as HFCs and SF 6, are not typically associated with agricultural sources [3]. Nitrous oxide is mainly emitted as a byproduct of nitrification (aerobic transformation of ammonium to nitrate) and denitrification (anaerobic transformation of nitrate to N 2 gas), while CH 4 is emitted through methanogenesis of organic carbon compounds under anaerobic conditions. These anaerobic conditions can occur in the soil, in stored manure, in an animal s gut during enteric fermentation (mainly in ruminants), or during incomplete combustion of burning organic matter. The cumulative GHG emissions from any human activity are commonly referred to as a carbon footprint. A report issued by the European Commission-Joint Research Center [4] defines carbon footprint as a measure of the exclusive total amount of CO 2 emissions that are directly or indirectly caused by an activity or is accumulated over the life stages of a product. A carbon footprint includes CO 2 emissions and N 2 OandCH 4 emissions, which are expressed in CO 2 equivalents (CO 2 e). For this study the GHGs included in the CO 2 ewerech 4 and N 2 O. A CO 2 eisthe concentration of CO 2 that would give the same levels of radiative properties as a given amount of CO 2.The global warming potential (GWP)is a measure of how much a given mass of GHG is estimated to contribute to global warming. This is calculated over a specified time period and must be stated whenever a GWP is stated. The GWP over 100 years for N 2 O is 298, and the GWP over 100 years for CH 4 is 25 [Intergovernmental Panel on Climate Change (IPCC) 1996]. This means that the emission of 1 million tons of N 2 O is equivalent to 298 million tons of CO 2 over 100 years, while the emission of 1 million tons of CH 4 is equivalent to 25 million tons of CO 2 over 100 years [2]. Much of the CO 2 e that is generated from the poultry industry is primarily from feed production, the utilization of fossil fuels, and manure management [5, 6]. While poultry producers do not have control over the production of the feed that is used on their farms, other GHG emissions occur on farms that are under their control. These emissions may be in the form of purchased electricity, propane used for heat and incineration of dead birds, diesel used in farm equipment (including generators), and emissions from manure management. Currently, the available data from actual farm activities that show the GHG emissions that occur on poultry production farms are limited. The objective of this study was to assess the GHG (CO 2,CH 4,andN 2 O) emissions that occur while under the control of the grower on poultry production farms, specifically broiler, pullet, and breeder farms in South Georgia. MATERIALS AND METHODS The study was conducted in South Georgia evaluating the GHG emissions from broiler, pullet, and breeder farms within a broiler complex. The data collected represented the emissions that occurred within the farm gate, that is, only emissions that occurred on the farm and could be controlled by the poultry producer were assessed. A total of 109 farms with 627 houses were assessed; this included 87 broiler farms (538 houses), 15 breeder farms (55 houses), and 7 pullet farms (34 houses). The houses varied widely in age and structure. Three different house structures were observed: curtain-sided, solid-walled, and a combination of curtain-sided and solidwalled (i.e., one side curtain and the other side solid-walled). To evaluate the effect of house structure, 6 solid-walled houses, 8 curtain-sided houses, and 6 houses that had a combination of solid walls and curtains were assessed. The ages of the houses ranged from 5 to 24 years old. To evaluate the emissions based on age, houses aged 5, 10, 20, and 24 years were evaluated. We examined ten 5-year-old houses, eight 10-yearold, eight 20-year-old, and twelve 24-year-old houses. The houses used were selected based on their age and as such varied in structure. The emissions of houses that were the same age and had the same structure were also assessed. Data Collection and Evaluation Data were collected from a questionnaire distributed to and completed by the poultry producers. A 2-page questionnaire was developed and included detailed information on the farm operations and activity data. The farm information

3 DUNKLEY ET AL.: CARBON FOOTPRINT OF POULTRY FARMS 75 gathered included the number of houses on the farm, house size, house construction, method of waste disposal, number of birds per flock, number of flocks per year, and electricity and fuel usage. The activity data included the annual electricity usage in kilowatts per hour, annual propane use in gallons, and annual diesel fuel use in gallons. This information was obtained from farm records. The GHG emissions were evaluated using World Resource Institute (WRI) worksheets with emission factors based on region and animal type from IPCC Guidelines for National Greenhouse Gas Inventories [7]. A different WRI worksheet was used for each source (propane use, diesel use, electricity use) of emissions. For manure management, IPCC worksheets were used to calculate the emissions [8]. Emissions were computed based on the source of the emissions (activity data) and the emission type. Two types of emissions occur on farms, mechanical and nonmechanical emissions. Mechanical emissions result from fossil fuel use from purchased electricity, in mobile machinery, and in stationary machinery. Emissions from electricity use are considered an indirect emission because while the emissions do not occur on the farm, they do occur as a result of activities on the farm. Nonmechanical emissions result from manure management [8]. RESULTS AND DISCUSSIONS Agriculture is reportedly responsible for 6.3% of the GHG emissions in the United States, and of this 53.5% were a result of animal agriculture [9]. Of the emissions from animal agriculture, poultry was responsible for only 0.6% [9]. The primary GHGs emitted by agricultural activities are CO 2,CH 4,andN 2 O[2]. Livestock production contributes GHGs to the atmosphere both directly and indirectly. The majority of direct CO 2 emissions from animal agriculture is usually from fossil fuel use, for example, the use of propane or natural gas in furnaces or incinerators and the use of diesel gas to operate farm equipment and generators result mostly in CO 2 emissions, but some CH 4 and N 2 Oarealso emitted. The use of electricity on farms results in indirect emissions since they are the indirect consequence of the purchase and consumption of electricity and do not occur physically on site [7]. Mechanical Emissions Approximately 96% of these mechanical emissions from broiler and pullet houses were from propane use, while less than 5% of these emissions from breeder houses were from propane use (Table 1). Approximately 83% of the total mechanical emissions from the breeder house were from electricity use compared to less than 3% in broiler and pullet houses. Even though in a breeder house the majority of GHG emissions may derive from mechanical sources coming from electricity use, the total annual emissions (Table 1) from mechanical sources is lower (35 tons CO 2 e/year) when compared to a pullet house (448 tons CO 2 e/year) and broiler house (790 tons CO 2 e/year). Transportation fuel use on all three farm types was similar, and the annual electricity use was higher in breeder houses than in broiler and pullet houses. The high emissions from propane use in broiler and pullet houses are due to heating the houses during brooding and cold weather. Breeder farms do not house chicks, and thus brooding is not a factor in heating and results in a much lower propane usage. Nonmechanical Emissions Agricultural activities are the largest source of N 2 O emissions in the United States, accounting for 69% of the total N 2 O emissions for The majority of N 2 O emissions from animal agriculture is from manure management, which is the second largest (a distant second to agricultural soil management practices [9]) N 2 O emitter in the agricultural sector. For nonmechanical emissions, direct emissions can be a byproduct of digestion through enteric fermentation. Methane is a byproduct of microbial fermentation. Ruminant animals (such as cattle, goats, sheep) have a complex digestive tract. This complex system is designed for microbial fermentation of fibrous material, and these animals are usually the major CH 4 emitters. Poultry are nonruminant animals that have simple stomachs where little microbial fermentation taking place. The U.S. Environmental Protection Agency (EPA) [9] reported that animal agriculture emitted a total of million metric tons (Tg) CO 2 e from enteric fermentation and managed manure. Annual

4 76 JAPR: Research Report Table 1. Emissions from mechanical sources from broiler, breeder, and pullet houses. Mechanical sources 1 Broiler houses 2 Breeder houses 2 Pullet houses 2 Tonnes 3 CO 2 e Percent of total 4 Tons 3 CO 2 e Percent of total 4 Tons 3 CO 2 e Percent of total 4 Stationary combustion Transportation Electricity use Mechanical sources on farm where emissions are coming from. 2 Emissions from poultry houses on broiler, breeder, and pullet farms. 3 Emissions from poultry houses in tons CO 2 e. 4 Percentage of emissions from each of the three mechanical sources in different types of poultry production houses. Figure 1. Emissions from nonmechanical sources from broiler, breeder, and pullet farms. emissions from manure management (Fig. 1) showed that breeder houses had higher emissions (65.3 metric tons CO 2 e/year) compared to broiler houses (59 metric tons CO 2 e/year) and pullet houses (61.7 metric tons CO 2 e/year). Currently no emission factors are available to calculate CH 4 emissions from enteric fermentation in poultry. However, CH 4 emissions were calculated from manure management, and the results showed that an average breeder house emitted 32.5 metric tons CO 2 e/year compared to 15.3 metric tons CO 2 e/year for pullet houses and 8 metric tons CO 2 e/year for broiler houses. The higher CH 4 emissions observed from breeder houses versus pullet and broiler houses could be a result of the method of manure collection. In breeder houses some of the manure is collected in the center of the house in a litter, while some is collected under the slats in the houses. This build-up of manure under the slats is similar to conditions in some commercial layer houses where the manure is excreted and collected below the cages with no bedding to absorb moisture. In this type of manure management system, both CH 4 and N 2 O emissions are relatively low [10], but the CH 4 emissions are higher than if the manure were diluted with bedding material. Direct emissions also occur from the decomposition and nitrification/denitrification of livestock waste (manure and urine) where both CH 4 and N 2 O are emitted. Managed waste that is collected and stored also emits CH 4 and N 2 O (IPCC, 2000). Indirect emission of N 2 O occurs when nitrogen is lost from the system through volatilization as NH 3 and N x (nitric oxide and nitrogen dioxide). The amount of excreted organic nitrogen that changes to ammonia during manure collection and storage depends on time

5 DUNKLEY ET AL.: CARBON FOOTPRINT OF POULTRY FARMS 77 and temperature. In the case of poultry, uric acid is quickly mineralized into ammonia nitrogen, which, due to its volatility, is easily diffused into the surrounding air [11, 12]. The results observed during this study showed that an average broiler house emits approximately 51 metric tons CO 2 e/year of N 2 O(Fig.1), which was higher than pullet (46.5 metric tons CO 2 e/year) and breeder houses (32.8 metric tons CO 2 e/year). Poultry reared in management systems with litter and using solid storage has relatively high N 2 O emissions but low CH 4 emissions [10]. This is because the manure is stored under aerobic conditions, which are not favorable for CH 4 production. Broilers, pullets, and, to a lesser extent, breeders are reared using this manure management system. Total Emissions Because electricity use is an indirect emission that does not occur on a farm, it is represented in Table 1 separately from the other mechanical sources in the discussion of total emissions. When all (mechanical and nonmechanical sources) GHG emissions from each type of poultry house were evaluated (Table 2), the total for a broiler house was approximately 847 metric tons CO 2 e/year. Of this total, 90.8% were from fuel use (LPG and diesel) excluding electricity use (2.6%) and only 6.6% were from manure management (Table 2). The breeder house total emissions were metric tons CO 2 e/year, with only 5.6% of these emissions attributed to mechanical sources. A total of 26.9% of the total emissions on breeder houses were from electricity use, and the majority of the total emissions (67.4%) were from manure management. Pullet farms had an emission profile similar to that of broiler farms. Pullet houses had total emissions of metric tons CO 2 e/year, which was lower than those of broiler houses; however, fuel use represented 89.4% of the total emissions from pullet houses. Electricity use was 2.6% of the total emissions, and manure management was 7.9%. Other Variables The type of production system (broiler, pullet, or breeder) has an effect on the amount of GHGs emitted, but other factors, such as the age and structure of the house, can also determine the emission rates from each house. We evaluated 4 broiler farms that ranged in age from 5 to 24 years old, and the results revealed that the age of the house could have an effect on emission rates (Table 3). Five-year-old houses had lower emission rates ( metric tons CO 2 e/year) than 10-year-old (1, metric tons CO 2 e/year), 20-year-old ( metric tons CO 2 e/year), and 24-year-old (1, metric tons CO 2 e/year) houses. Even though the general trend was toward increased GHG emissions with an increasing house age, the 20-year-old house had lower emissions than the 10-year-old house. This could be a result of how the houses are equipped. Newer houses may have more fans. A comparison was made between 3 broiler farms that were of similar ages but had different types Table 2. Total emissions from broiler, breeder and pullet houses. Farm type 1 Mechanical emissions 2 Nonmechanical Electricity usage Total GHG emissions 2 emissions 2,3 emissions 4 CO 2 e % CO 2 e % CO 2 e % Broiler houses Breeder houses Pullet houses Indicates the type of farm emissions (in tons CO 2 e) are coming from. 2 Indicates the sources of the emissions (in tons CO 2 e) from different types of poultry production houses. 3 Electricity usage is calculated separately from the other mechanical sources because emissions from electricity use do not occur on farms. 4 Indicates the total GHG emissions (in tons CO 2 e) from different types of poultry production houses.

6 78 JAPR: Research Report Table 3. Emissions from 4 broiler farms based on age of houses. Age of house 1 Electricity 2 Propane 2 Diesel 2 Total GHG 3 CO 2 e CO 2 e CO 2 e CO 2 e Figures in this column represent the ages of the houses from 4 broiler farms. 2 Figures in these columns represent the GHG emissions from different sources (electricity, propane, and diesel use) in tons CO 2 e per year. 3 Figures in this column represent the total GHG emissions from houses based on age. There were eight 10-year-old houses, eight 20-year-old houses, and twelve 24-year-old houses. Table 4. Greenhouse gas emissions from three 6-house broiler farms of similar age but different house structures. House structure 1 Diesel use 2 Propane use 2 Electricity use 2 Total GHG 3 TCO 2 e TCO 2 e TCO 2 e T CO 2 e Combination sides Curtain-side Solid-walled Indicates the different house structures. 2 Indicates emissions (in tons CO 2 e) from each source based on house type. 3 Indicates the total GHG emission (in tons CO 2 e) from each house type. Table 5. Greenhouse gas emissions from 4 broiler farms with 4 curtain-sided houses each and all the same age (16 years). Farm 1 Diesel use 2 Propane use 2 Electricity use 2 Total GHG 3 TCO 2 e TCO 2 e TCO 2 e T CO 2 e Farm Farm Farm Farm Four 16-year-old, 4-house farms with curtained sides. 2 Indicates GHG emissions in tons CO2e from different sources on each farm. 3 Indicates total GHG emissions in tons CO2e from each farm. of house structure (Table 4). The house structures assessed were curtain-sided, solid-walled, and a combination of these two. This assessment revealed that emissions from diesel fuel and electricity use in all house types were similar. However, the similarities ended there; solidwalled houses had lower emissions from propane use ( metric tons CO 2 e) and overall lower emissions than the other two structural types. Houses with a combination of both curtains and solid walls had lower emissions from propane use (1, metric tons CO 2 e) and overall lower emissions than houses that had curtained sides (1, metric tons CO 2 e from propane use). Another comparison was made between four 16-year-old, 6-house farms, each with curtained sides (Table 5). All 4 farms had different GHG emission rates ranging from a low of 917 metric tons CO 2 e/year to a high of 1,757.8 metric tons CO2e/year. Therefore, farms should be evaluated individually to ascertain the GHG emissions because no two farms, regardless of age or house structure, are exactly alike. Management practices that result in improvements in energy use help to reduce the use of fossil fuels, specifically propane on poultry farms.

7 DUNKLEY ET AL.: CARBON FOOTPRINT OF POULTRY FARMS 79 CONCLUSIONS AND APPLICATIONS It is pertinent to note that the results reported in this paper represent average emissions from each type of house in a specific region of the United States. The broiler and pullet houses evaluated in this study were approximately 20,000 ft 2 and housed approximately 23,000 birds per flock. The breeder houses were approximately 64,000 ft 2 and housed approximately 36,000 birds. The average kilowatt usage was 221,964 kw for broiler housesand approximately 101,341 kw for pullet houses; an average breeder house used 172,008 kw. 1. Emissions from poultry production farms can be assessed based on the sources of the emissions. By identifying the source of emissions, producers can pinpoint the areas where GHGs are being emitted, which would then allow them to address specific problems to mitigate these emissions. 2. Mechanical emissions occur when fossil fuels are used to generate energy, and nonmechanical emissions result from enteric fermentation and manure management. Broiler and pullet houses have higher mechanical emissions from propane use than breeder houses because they utilize more propane in these operations for heating and brooding purposes. Broiler and pullet houses have lower nonmechanical emissions than breeder houses because of the way in which manure is managed in these operations. 3. While the age and structure of a house can affect the rate of emissions, houses of a similar age and structure can have different emission rates, and for this reason farms should be assessed individually for GHG emissions. REFERENCES AND NOTES 1. EPA, Designing a U.S. greenhouse gas emissions registry. Climate and Energy Policy Series. World Resources Institute, epa.gov/ghgreporting/basicinformation/index.html. 2. Intergovernmental Panel on Climate Change (IPCC) Climate Change The Science of Climate Change. The Contribution of Working Group I to the Second Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, New York. 3. Johnson, J. M., A. L. Franzluebbers, S. L. Weyers, and D. C. Reicosky Agricultural opportunities to mitigate greenhouse gas emissions. Environ. Pol. 150: European Commission-Joint Research Center European platform on life-cycle assessment. (Accessed February 22, 2012). 5. Pelletier, N Environmental performance in the US broiler poultry sector: Life cycle energy use and greenhouse gas, ozone depleting, acidifying and eutrophying emissions. Agric. Syst. 98: Environmental Working Group Meat eaters guide: Methodology. Hamerschlag, K., and K. Venkat. eds. 7. World Resources Institute WRI/WBCSD GHG protocol initiative calculation tool. org. 8. Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories. Penman, J., M. Gytarsky, T. Hiraishi, W. Irving, and T. Krug. eds. 9. U.S. Environment Protection Agency (EPA) Chapter 6: Agriculture. Inventory of U.S. greenhouse gas emissions and sinks climatechange/emissions/downloads10/us-ghg-inventory -2010_Chapter6-Agriculture.pdf 10. Intergovernmental Panel on Climate Change (IPCC) Good practice guidance and uncertainty management in national greenhouse gas inventories. Penman, J., D. Kruger, I. Galbally, T. Hiraishi, B. Nyenzi, S. Emmanuel, L. Buendia, R. Hoppaus, T. Martinsen, J. Meijer, K. Miwa, and K. Tanabe. eds. IPCC/IGES, Hayama, Japan. 11. Asman, W. A. H., M. A. Sutton, and J. K. Schjoerring Ammonia: Emission, atmospheric transport and deposition. New Phytol. 139: Monteny, G. J., and G. W. Erisman Ammonia emissions from dairy cow buildings: A review of measurement techniques, influencing factors and possibilities for reduction. Neth. J. Agric. Sci. 46: