Greenhouse Gas Emissions in Montgomery County, Pennsylvania ...

Greenhouse Gas Emissions in Montgomery County, Pennsylvania 1990-2004

Sarah E. Knuth M.S. Degree Candidate Department of Geography Penn State University 20 July 2006

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Introduction This document presents the results of a greenhouse gas emissions inventory compiled for Montgomery County from March 2005 to November 2006, using methods described in the report Measuring Greenhouse Gas Emissions in Montgomery County 1990-2004: Technical Report (Knuth, 2006a). The inventory tracks county GHG emissions from 1990 to 2004, investigating a number of emissions sources, sinks, and drivers. This report presents overall inventory results, then examines more detailed findings by sector. A Global Warming Plan of Action for Montgomery County, Pennsylvania: Greenhouse Gas Emissions Reduction Strategies (Knuth, 2006c) presents options for reducing the county’s GHG emissions. Background Information Earth’s temperature is regulated by a collection of trace atmospheric gases, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), that trap outgoing heat in the atmosphere and re-radiate it back to the earth’s surface. Human activities over the past 150 years, including burning fossil fuels for energy, deforestation, intensive agriculture, and other processes, have dramatically increased atmospheric concentrations of these natural greenhouse gases (GHGs) and added potent man-made GHGs to the atmosphere. Scientific consensus indicates that continued high levels of human GHG production will force significant and long-term alterations in Earth’s climate; most directly, an increase in average planetary temperatures. Potential impacts of this warming include increased incidence of heat waves, droughts, and severe storms; melting of ice caps and global sea level rise; and species extinctions (IPCC, 2001). The seriousness of these projected impacts is increasingly prompting citizens and policymakers to take steps to reduce GHG emissions. GHG emissions inventories establish places’ baseline GHG emissions and reveal important emissions sources and sinks. Stakeholders may use this information to explore trends in GHG emissions, target emissions reduction strategies, and track progress in reducing emissions. Traditionally, inventories calculate GHG emissions by tracking levels of known GHG emissions-producing/reducing activities, then multiplying these activity data by nationally-derived emissions coefficients (e.g., EIIP, 1999). Emissions are often expressed in metric tons of carbon-equivalent units (MTCE): GHG Emissions (MTCE) = Activity Data * GHG Emissions Coefficients Figure 1 shows GHG emissions sources and sinks inventoried for Montgomery County1 These include emissions from energy use, transportation, solid waste disposal and wastewater treatment, agriculture, and forest management and land-use change.

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Data unavailability prevented final inclusion of emissions from industrial processes and off-road transportation.

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Figure 1: Montgomery County GHG Emissions Sources and Sinks Overall Results Montgomery County’s overall GHG emissions increased almost every year from 1990 to 2004. Total emissions grew from about 2.6 million metric tons of carbonequivalent GHG emissions (MTCE) in 1990 to almost 3.6 million MTCE in 2004, a 36 percent increase (Figure 2). Three GHG emissions sources – electricity consumption, onsite fuel use, and transportation – dominate Figure 2’s emissions trends.

Figure 2: Montgomery County GHG Emissions (MTCE) 1990-2004

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Figure 3 quantifies the sector GHG emissions shares shown in Figure 2. In general, energy-related fossil fuel combustion dominates Montgomery County GHG emissions. Electricity use, on-site fuel consumption, and transportation energy use were the top three sources of GHG emissions in 1990, making up 33 percent, 44 percent, and 27 percent of total emissions, respectively (Figure 3). GHG emissions from wastewater and sludge treatment and agriculture were much less significant at only 0.1 percent and 1 percent of total emissions. Solid waste disposal and forest management change were net GHG emissions sinks in 1990. In 2004, stationary energy use and transportation continued to dominate GHG emissions (electricity made up 34 percent of total emissions, on-site fuel consumption 30 percent, and transportation 25 percent). Wastewater and sludge treatment and agriculture remained minor emissions sources (0.1 percent and 0.3 percent of total emissions, respectively). The primary difference between 1990 and 2004 GHG emissions shares was the growing significance of GHG emissions from solid waste disposal and forest management. Both of these sectors became net sources of GHG emissions over the last fifteen years, making up 3 percent and 7 percent of 2004 GHG emissions, respectively. Growth in the proportional importance of these sectors occurred at the expense of on-site fuel consumption. GHG emissions in the latter sector remained fairly stable, and its trends were outstripped by more pronounced trends in other sectors.

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Figure 3: Montgomery County GHG Emissions (MTCE): Sector Percent Share in 1990 and 2004 As Figure 3 indicated, different sectors’ GHG emissions grew at different rates. Figure 4 shows net growth in GHG emissions per sector between 1990 and 2004. Montgomery County’s population grew about 14 percent over this period, increasing from about 678,000 to 774,000 residents. Most sectors’ GHG emissions grew at a greater rate than population. Electricity consumption and transportation emissions grew 42 percent and 25 percent, respectively, over the past fifteen years. Emissions from solid 5

waste disposal and forest management grew much more: 192 percent and 336 percent, respectively. Because the inventory calculated GHG emissions from county wastewater and sludge treatment using population trends, emissions from this sector showed the same 14 percent increase as population over the past fifteen years. Finally, two sectors’ emissions decreased slightly between 1990 and 2004. GHG emissions from agriculture fell 29 percent, and emissions from on-site fuel consumption decreased by 7 percent. Onsite fuel consumption’s emissions fluctuated substantially from year to year, so this downturn is probably temporary and is at least in part an artifact of the two specific years used to summarize GHG emissions trends.

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Figure 4: Montgomery County GHG Emissions: Percent Change 1990-2004 Electricity Consumption Burning fossil fuels to generate electricity produces CO2 (Fuel impurities and incomplete combustion can also produce small amounts of CH4 and N2O, but data to calculate these emissions were unavailable at the county level.) The inventory measured CO2 emissions from Montgomery County’s residential, small commercial and industrial (SCI), and large commercial and industrial (LCI) electricity consumption between 1990 and 2004. Electricity consumed in Montgomery County is generated by plants in the Pennsylvania-New Jersey-Maryland (PJM) Interconnection regional power pool and distributed by PECO Energy Company/Exelon (PECO), PPL Electric Utilities Corporation (PPL), and Metropolitan Edison Company. PECO serves the five-county Philadelphia metropolitan area and is Montgomery County’s dominant electric utility. Figure 5 reports CO2 emissions for PECO, PPL, and Metropolitan Edison electricity customers, with PECO customers’ emissions reported by sector. CO2 emissions from county electricity consumption grew from about 860,000 MTCE to 1.2 million MTCE over the fifteen-year period. This emissions increase was uneven; growth periods (19926

1995 and 2000-2003) were punctuated by periods of stable or slightly declining emissions (1990-1992, 1995-2000, and 2003-2004). Examining forces driving electricity sector CO2 emissions helps explain Figure 5’s variable emissions trends. According to inventory calculations, Montgomery County electricity consumption grew steadily between 1990 and 2004 (Figure 6). SCI electricity use grew the most, LCI the least. Much of Figure 5’s variability stems from changes in the average CO2 emissions intensity of the Pennsylvania-New Jersey-Maryland (PJM) Interconnection’s electricity generation. Figure 7 tracks this intensity from 1990 to 2004 (hollow data points pre-1996 indicate intensities estimated due to data unavailability). Electricity generation in PJM’s power pool grew steadily less CO2-intensive between 1996 and 2000 but reversed this trend between 2000 and 2003 (2004’s electricity generation was slightly less CO2–intensive than 2003’s). When multiplied by electricity use, these changing CO2 emissions coefficients alternately mitigate (1996-2000; 2004) and exacerbate (2000-2003) electricity consumption’s emissions.

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Figure 5: Montgomery County GHG Emissions (MTCE) 1990-2004: Electricity Consumption

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Figure 6: Montgomery County Electricity Consumption (PECO Service Area) 19902004

Emissions Intensity (lbs CO2/kWh)

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Figure 7: PJM Interconnection CO2 Emissions Intensity: 1990-2004 On-Site Fuel Consumption Residential, SCI, and LCI sector facilities burn fossil fuels (most commonly natural gas, petroleum fuels, and coal) on-site for a variety of purposes (e.g., space heating, water heating, and industrial processes). Fossil fuel combustion produces CO2 as well as small amounts of CH4 and N2O from fuel impurities and incomplete combustion. The inventory measured CO2 emissions from Montgomery County’s residential, SCI, and LCI on-site fuel consumption. Data constraints prevented the inventory from including CH4 and N2O emissions in the GHG inventory. PECO provides utility natural gas service to Montgomery County. UGI Utilities, Inc. (UGI), the only other gas utility in the region, served slightly over 1,600 Montgomery County natural gas customers in 2004 (UGI, 2004), an insignificant share next to PECO’s 152,000 county customers (PECO, 2004b). Therefore, the inventory does not include UGI’s Montgomery County customers or consumption in the inventory. Numerous smaller, 8

non-utility companies provide oil, coal, and other renewable and non-renewable fuels to Montgomery County customers. To calculate CO2 emissions from Montgomery County on-site fossil fuel use, the inventory first determined Montgomery County residential, SCI, and LCI sector consumption of natural gas, petroleum fuels (i.e., residual fuel oil, distillate fuel oil, liquefied petroleum gas, and kerosene), and coal from 1990 to 2004. It then multiplied fuel consumption in million British Thermal Units (BTU) by each fuel’s carbon (C) content and proportional oxidization to CO2 using EIIP (1999) coefficients to express emissions in MTCE. According to inventory calculations, GHG emissions from on-site fuel consumption fluctuated from year to year but averaged about 1 million MTCE annually (see Figure 8). Each sector showed similar year-to-year variability. Due to inventory methods, these shifts are linked to trends in overall gas use by PECO customers. Figure 9 estimates different fuel types’ contribution to GHG emissions in each sector in 1999. Natural gas from utilities and oil are the most important fuels used in the area, respectively contributing 53 and 45 percent of GHG emissions in the residential sector, 56 and 42 percent in the SCI sector, and 39 and 60 percent in the LCI sector. Coal is a minor contributor in each sector at 1 percent or less of total GHG emissions, and bottled gas/liquid petroleum gas (LPG) is a minor source of residential GHG emissions at 2 percent of total sector emissions. In the residential and SCI sectors, use of utility natural gas increased relative to oil from 1990 to 2004. This proportional increase moderated residential and SCI GHG emissions because natural gas combustion produces fewer GHG emissions than oil combustion. Data unavailability precluded the inventory from tracking changing fuel-type importance in the LCI sector.

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Figure 8: Montgomery County GHG Emissions (MTCE) from On-Site Fuel Consumption 1990-2004

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Figure 9: GHG Emissions from On-Site Fuel Consumption 1999: Emissions Share by Fuel Type Transportation Transportation-related fossil fuel consumption produces CO2 and small amounts of CH4 and N2O from fuel impurities and incomplete combustion. The inventory tracked Montgomery County’s on-road CO2, CH4, and N2O emissions for gasoline- and dieselburning passenger cars, light trucks, and heavy trucks. It calculated emissions based on total miles of travel. County-level data constraints did not permit reporting motorcycle and bus GHG emissions as separate categories, although having this information would have been useful to inform mitigation strategies. The inventory was unable to include several smaller sources of transportation GHG emissions. First, idling in traffic produces excess fuel consumption and a small amount of extra GHG emissions; this information is summarized in Appendix A. The inventory also did not report GHG emissions from nonroad modes of transportation (e.g., airplanes, boats, trains, farm and construction equipment, snowmobiles), due to a combination of data unavailability at the county level and boundary allocation problems (judging who is responsible for marine and air travelrelated GHG emissions is difficult to impossible at the local level). To calculate CO2 emissions from Montgomery County on-site fossil fuel use, the inventory first determined annual on-road vehicle miles traveled (VMT) in Montgomery County, then determined the proportion of VMT contributed by different vehicle types. It multiplied VMT by vehicle type by the inverse of EPA fuel economy by vehicle type to calculate gasoline and diesel use. It then used EIIP (1999) formulas and emissions coefficients to calculate CO2 emissions from fuel consumption, and CH4 and N2O emissions from VMT by vehicle type. Transportation GHG emissions grew from about 700,000 MTCE in 1990 to almost 900,000 MTCE in 2004 (Figure 10). Light-duty gasoline vehicles (i.e., passenger cars) accounted for, on average, 61 percent of total emissions, with light-duty gasoline trucks a distant second at 21 percent. Heavy-duty diesel vehicles and heavy-duty gasoline vehicles contributed smaller amounts to total emissions – 10 percent and 8 percent, respectively. GHG emissions from light-duty diesel vehicles and trucks were

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relatively insignificant. These emissions shares corresponded roughly to different vehicle types’ proportional contributions to VMT. However, relatively low vehicle fuel economy in light-duty gasoline trucks and, especially, heavy-duty gasoline and diesel trucks inflates the significance of these sources’ GHG emissions relative to their share of VMT. Figure 11 demonstrates this relationship by comparing county GHG emissions and VMT in 2003. At 6.9 billion, Montgomery County’s 2003 VMT was the second highest in Pennsylvania (only surpassed by Allegheny County), 1 to 2 billion higher than any other county in the Philadelphia area. Appendix A constructs an additional GHG emissions baseline to consider energy wasted and GHG emissions produced from vehicles idling in heavy traffic.

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Figure 10: Montgomery County GHG Emissions (MTCE) from Transportation 1990-2004

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Figure 11: Montgomery County Vehicle Miles Traveled and GHG Emissions 2003: Percent Share by Vehicle Type Solid Waste Disposal GHG emissions from solid waste disposal are determined by three emissions sources and one emissions sink. First, solid waste that municipalities deposit in landfills releases CH4 as a result of anaerobic waste decomposition; rates of landfill CH4 emissions depend on total landfill waste in place, climate, and other landfill characteristics. Landfill CH4 can be removed by CH4 flaring and recovery for waste-toenergy programs. Industrial waste disposal and decomposition also produces CH4 emissions, and incineration of municipal sold waste releases CO2 and N2O. Finally, municipal solid waste disposal in landfills also acts as an emissions sink because it sequesters C for long periods. In calculating GHG emissions from Montgomery County waste disposal, the inventory considered all landfills to which Montgomery County exports waste, both within county boundaries and in other Pennsylvania counties. It tracked all types of waste deposited in municipal landfills, including municipal waste, residual waste, sewage sludge, infectious waste, construction waste, ash residue, and asbestos. Data was not available to compute waste deposited at out-of-state landfills; it was assumed that this total is small. This boundary allocation decision links GHG emissions from waste disposal to Montgomery County consumption. The inventory did not account explicitly for waste diverted from the waste stream via recycling and did not attempt to calculate GHG emissions produced during the entire lifetime of disposed products (e.g., energy needed to extract and process raw materials, transport products, etc.). The inventory calculated CH4 emissions from municipal solid waste disposal to landfills by multiplying cumulative waste at Montgomery County destination landfills by EIIP (1999) emissions coefficients estimating CH4 emissions per unit of waste (MTCE). It determined CH4 emissions from industrial solid waste disposal to landfills using the previous equation’s results and an EIIP (1999) proxy method. The inventory calculated CO2 and N2O emissions from municipal solid waste incineration by multiplying annual Montgomery County waste incineration by EIIP (1999) emissions coefficients. Finally, it

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established C sequestration from solid waste disposal to landfills by multiplying Montgomery County annual municipal solid waste disposal to landfills by EIIP (1999) emissions coefficients estimating C sequestered per unit waste. Montgomery County GHG emissions from solid waste disposal increased from about -54,000 MTCE in 1990 to 104,000 MTCE in 2004 (Figure 12). Solid waste disposal was a net GHG emissions sink in 1990 and 1991 because carbon sequestration from landfilled municipal waste exceeded CH4 emissions from municipal and industrial waste landfilling and CO2 and N2O emissions from waste incineration. Although total municipal waste disposal increased steadily between 1990 and 2004 (Figure 13), the amount of waste sent to landfills declined after the Montenay Energy Resources of Montgomery County, Inc. (MERMCI) incineration facility opened in 1991. This shift simultaneously reduced annual landfill carbon sequestration and landfill CH4 emissions (the latter less so, because landfill CH4 emissions are dependent on cumulative waste in place and are therefore less sensitive to year-to-year changes). Industrial landfilling remained a minor source of CH4 emissions. Waste incineration also produced CO2 and N2O emissions. The waste sector produced positive GHG emissions from 1992 to 2004. As MERMCI reached maximum annual capacity, increasing total waste disposal diverted more waste to landfills, and landfill CH4 emissions and carbon sequestration increased again. Finally, landfill CH4 recovery programs at most of Montgomery County’s major destination landfills significantly reduced total emissions, lessening the GHG emissions impact of increasing waste disposal to landfills.

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Figure 12: Montgomery County GHG Emissions from Solid Waste Disposal 19902004

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Waste Disposed of Annually (Tons)

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Figure 13: Montgomery County Annual Municipal Solid Waste Disposal (Tons) 1990-2003 Wastewater and Sludge Treatment Processing municipal sewage sludge and wastewater produces small amounts of N2O and CH4 emissions. Processing practices that minimize anaerobic decomposition or recover gases produced can reduce GHG emissions, but local data availability did not permit including these emissions-reducing methods. To calculate CH4 emissions from Montgomery County wastewater and sludge treatment following EIIP (1999) methods, the inventory multiplied total county population by average per capita waste production, the proportion of waste kept as wastewater and removed as sludge, and, for each, CH4 produced per unit of waste and the average proportion of waste treated anaerobically. It subtracted CH4 recovered from these totals. To determine N2O emissions from wastewater and sludge, the inventory multiplied average United States per capita protein consumption by the percent N in protein, Montgomery County population, and an emissions factors that converted N to N2O emissions. Montgomery County CH4 and N2O emissions from sludge and wastewater treatment were insignificant relative to most other GHG emissions sources. However, wastewater and sludge emissions grew steadily between 1990 and 2004, driven by increasing county population (Figure 14).

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Figure 14: Montgomery County GHG Emissions from Wastewater and Sludge Treatment 1990-200 Forest Management Forests sequester C in trees and forest canopy, undergrowth, roots, and forest soils. When forests are altered so that the forest ecosystem stores less C per acre or total acres of forest land are reduced, these changes are expressed as CO2 emissions (i.e., releases of stored C). The inventory measured Montgomery County C sequestration and CO2 emissions from contiguous forested areas. Although street trees and other vegetation types also sequester C, lack of data precluded including these emissions sinks in Montgomery County’s inventory. Using a basic version of EIIP (1999) formulas, the inventory calculated C sequestration/C-equivalent CO2 emissions released from forest management and land-use change by multiplying average C storage per unit of forest land by total forest land from 1990 to 2004. It expressed gains in C storage as negative CO2 emissions and losses in C storage as positive CO2 emissions. Montgomery County’s forest sector changed from a GHG emissions sink in 1990, registering a 74,000 MTCE increase in carbon sequestered in trees, undergrowth, and forest soils, to a CO2 source in 2004, emitting over 247,000 MTCE (Figure 15). Loss of forested land in the county drove this trend toward decreasing forest carbon sequestration and increasing GHG emissions. Land-cover trends indicate that the county has lost almost 25 percent of its forest land over the last fifteen years (see Figure 16; emphasized data points indicate land-cover inventory years). Increasing average carbon storage per forest acre (the inventory measured a 13 percent increase between 1990 and 2004)

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exerted a moderating influence on forest GHG emissions. Increasing carbon storage per forest acre drove the inventory’s early trend toward carbon sequestration, but the magnitude of county forest loss converted the forest sector to a net emissions source in 1996. Since then, growing annual loss of forest land has produced increasingly large GHG emissions.

Montgomery County CO2 Emissions (MTCE) from Forest Management 1990-2004 300,000 250,000


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Figure 15: Montgomery County CO2 Emissions (MTCE) from Forest Management 1990-2004

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Figure 16: Change in Montgomery County Forest Land (Hectares) 1990-2004. Emphasized data points represent years for which data was present; other points are interpolated or extrapolated.

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Agriculture Various agricultural practices release GHG emissions. Livestock emit CH4 during digestion (enteric fermentation), particularly ruminant livestock (e.g., cattle and sheep). Manure management produces various levels of CH4 and N2O emissions, depending on total volume of manure and the type of manure management system utilized (e.g., pit storage, solid storage, anaerobic lagoon, etc.), which varies by region and livestock type. Some farmers cultivating wheat, rice, and sugarcane burn agricultural crop waste, releasing CO2 and N2O emissions (of these crops, only wheat is produced in Montgomery County). Finally, various agricultural soil management practices produce GHG emissions. Nitrogen (N) fertilizer application to agricultural crop and pasture land produces N2O emissions directly, via leaching and runoff, and through volatization to NH4 and NOx (N in these gases eventually converts to N2O). Livestock manure applied to agricultural soils through daily spread operations or in pastures also contributes to N2O emissions directly, through leaching and runoff, and via volatization to NH4 and NOx. Incorporation of crop residues into agricultural soils and cultivation of N-fixing crops (e.g., soybeans, alfalfa, lentils) produce N2O emissions directly. Finally, lime application to agricultural soils produces CO2 emissions. The inventory measured Montgomery County agricultural GHG emissions from all sources described above. Rice cultivation is an important source of agricultural CH4 emissions, but Montgomery County produces no rice. Also, lack of county-level data prevented the inventory from including N2O emissions from soil management practices including organic fertilizer use and cultivation of high-organic content histosols; these omissions are probably minor. First, the inventory calculated CH4 emissions for each type of livestock by multiplying livestock populations by CH4 production per head (EIIP, 1999). It determined CH4 emissions from manure management by multiplying livestock populations by average animal mass (TAM), volatile solids (VS) produced, and CH4producing capacity to find maximum potential CH4 emissions, then multiplied this total by percent use of different manure management systems and each system’s CH4 percent conversion factor. The inventory found N2O emissions from manure management by multiplying livestock populations by average animal mass, N produced per unit of mass, the percent of manure managed, and the amount of N in manure unvolatized to find total N in managed manure, then multiplied this total by the percent of manure in each management system and each management system’s N2O emissions factor. Next, it calculated CO2 emissions and N2O emissions from agricultural waste burning in Montgomery County by multiplying county production of crops whose waste is burned by EIIP (1999) coefficients estimating total residue produced, amount burned, percent dry matter produced, burning efficiency, combustion efficiency, and C content (for CO2 emissions) or N content (for N2O emissions). Finally, the inventory calculated N2O and CO2 emissions from agricultural soils using several equations. First, to estimate direct N2O emissions from soil management practices, it first multiplied annual synthetic fertilizer use by an EIIP (1999) coefficient calculating N2O emissions. It found additional N2O emissions by multiplying the total N content of county livestock manure by the percent of manure managed as daily spread and an N2O emissions coefficient for this practice. The inventory determined N2O emissions from integrating crop residues into soil by multiplying crop production by EIIP (1999) coefficients estimating the

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amount of residue each crop produces, the fraction of residue incorporated back into the soil, the residue’s N content, and the amount of N that converts to N2O emissions (MTCE). Finally, the inventory found N2O emissions from cultivation of N-fixing crops by multiplying annual production of these crops by EIIP (1999) coefficients estimating total residue production, N content, and N conversion to N2O emissions (MTCE). Second, to calculate N2O emissions from animal manure deposited on pasture, range, and paddock, it multiplied the N content of county manure by the EIIP (1999) estimated percent of manure deposited on pasture, range, and paddock and N2O emissions coefficient for this practice. Third, it used synthetic fertilizer application, manure production, and N content information calculated in previous equations with EIIP (1999) emissions coefficients to calculate the fraction of N in fertilizer and manure that volatizes to NOx and NH4, and the fraction that is removed from the soil in leaching and runoff (both processes eventually produce N2O emissions). Finally, the inventory determined CO2 emissions from lime application to agricultural soils by multiplying county lime use by an EIIP (1999) CO2 emissions factor. Montgomery County’s agricultural GHG emissions declined from 1990 to 2004, from about 17,000 MTCE annually to just under 14,000 MTCE (Figure 17). GHG emissions from almost all agricultural sources – including livestock direct emissions, manure management, burning of crop residues, nitrogen-fixing crop production, and lime application to agricultural soils – also declined from 1990 to 2004. Decreases can be attributed to declining crop production for most crops and livestock population over the past fifteen years (see Figure 18 and 19, respectively). Corn production does not follow this general decline. Rather, it fluctuates from year to year. In addition, the populations of some types of livestock (i.e., horses, sheep, goats, and mules) increased slightly between 1990 and 2004. However, more significant decreases in cattle and swine production outweigh these minor increases. GHG emissions from synthetic nitrogen fertilizer use fluctuated over the study period as fertilizer use changed from year to year (see Figure 20). These trends in fertilizer use may be tied to weather or economic conditions. In contrast, agricultural lime use declined over the past fifteen years. In conclusion, a variety of driving forces overlap to determine agricultural GHG emissions; emissions from this source are at once the most complex and (with the exception of wastewater and sludge) the least significant overall.

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Figure 17: Montgomery County GHG Emissions (MTCE) from Agriculture 19902004

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Figure 18: Montgomery County Grain Crop Production (Bushels) 1990-2004

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Figure 19: Montgomery County Livestock Populations 1990-2004

Figure 20: Montgomery County Synthetic Nitrogen Fertilizer Consumption (Tons) 1990-2004

Nitrogen Fertilizer Consumption (Tons)

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Recapitulation This chapter has presented the results of Montgomery County’s GHG emissions inventory, evaluating changes in and the significance of various GHG emissions sectors, sources, and sinks. The chapter has also explored forces driving changes in each sector’s GHG emissions.

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References EIIP (1999). Estimating Greenhouse Gas Emissions. EIIP Documentation Series, Volume VIII. Washington, DC: Greenhouse Gas Committee, Emissions Inventory Improvement Program, and US Environmental Protection Agency. http://www.epa.gov/ttm/chief/eiip/techreport/volume08/index.html. Intergovernmental Panel on Climate Change (IPCC) (2001). Knuth, Sarah (2006a). Measuring Greenhouse Gas Emissions in Montgomery County 1990-2004: Technical Report. Report compiled for the Montgomery County Planning Commission. Knuth, Sarah (2006c). A Global Warming Plan of Action for Montgomery County, Pennsylvania: Greenhouse Gas Emissions Reduction Strategies. Report compiled for the Montgomery County Planning Commission.

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