Greenhouse gas inventory of the Petroleum Company of ......takes place within PETROTRIN. Industrial...

Greenhouse gas inventory of the Petroleum Company of Trinidad and Tobago (PETROTRIN)

B. Singh1 & K. Ramnath2 1Département de géographie, Université de Montréal, Canada 2PETROTRIN, Pointe-à-Pierre, Trinidad and Tobago

Abstract

An inventory of greenhouse gas (GHG) emissions of the Petroleum Company of Trinidad (PETROTRIN), covering a ten-year period (1990-1999), is undertaken. PETROTRIN is a state-controlled energy company, and as part of its corporate responsibility with regards to environmental preservation and sustainability, it has undertaken an inventory of its emissions and removals. Furthermore, such an inventory provides useful and tangible information insofar as potential Clean Development Mechanism (CDM) projects are concerned. The Revised IPCC (Intergovernmental Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories are used to undertake the calculations of emissions and removals for five sectors, namely energy, industrial processes, agriculture, land use change and forestry and wastes. As to be expected, the overwhelming majority of CO2 emissions are derived from the Energy sector: using the Reference Approach, CO2 emissions range from 2,547 Gg (1993) to 7,465 Gg (1998). These emissions are mainly from refinery activities. However, CO2 and CH4 emissions from fugitive emissions, although they can be significant, are not well documented. Keywords: greenhouse gases, emissions, climate change, inventory, mitigation.

1 Introduction

The Petroleum Company of Trinidad and Tobago Limited (PETROTRIN), a state-owned fully integrated oil company, as part of its corporate responsibility to environmental preservation and sustainability and its obligation to the National Inventory of greenhouse gases (GHGs) of Trinidad and Tobago, as

Air Pollution XII, C. A. Brebbia (Editor)© 2004 WIT Press, www.witpress.com, ISBN 1-85312-722-1

required under the UNFCCC framework, has undertaken an inventory of its own GHG emissions and removals. This inventory is done for ten consecutive years, namely 1990 to 1999, inclusively. The year 1990 corresponds to the reference year for Trinidad and Tobago’s First National Communication and the years following, up to 1999, updates the inventory with more recent data. The GHG Inventory was done on an individual sector basis for the Energy, Industrial Processes, Agriculture, Land Use Change and Forestry and Wastes Sectors. The IPCC Revised 1996 Guidelines for National Greenhouse Gas Inventories (Houghton et al. [2]) together with the IPCC Good Practice Guidelines and Uncertainty Management (Penman et al. [4]) were used as the basis to undertake the necessary calculations on GHG Emissions and Removals. The IPCC Guidelines are designed for undertaking GHG inventories at the country level. The methodology used in this report is however customized and adapted for application at the company level, namely PETROTRIN (Singh and El Fouladi [5]). Furthermore, the calculations integrated, where required and relevant, the Compendium of Greenhouse Gas Emissions Estimation Methodologies for the Oil and Gas Industry of the American Petroleum Institute (API [1]). The Inventory of the following main Greenhouse Gases (GHG’s) was conducted for PETROTRIN: Carbon Dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O). Other greenhouse gases that contribute to tropospheric Ozone (O3) formation, such as Non-Methane Volatile Organic Compounds (NMVOC), Carbon Monoxide (CO) and Nitrogen Oxides (NOx) were also included in the inventory. In accordance with the Guidelines set out by the IPCC, carbon dioxide emissions from International Bunkers and burning of Biomass are not included in PETROTRIN’s total emissions and removals, since these activities are not relevant. This paper provides a detailed description of the appropriate methodologies used and an in-depth analysis and interpretation of the data generated on anthropogenic GHG emissions and sinks, on a sector-by-sector basis for PETROTRIN.

2 Methodology

2.1 Energy sector

2.1.1 CO2 and non CO2 emissions/removals Both the aggregate fuels supply-based and top-down Reference Approach and the policy-oriented source categories bottom-up Sectoral Approach were used to calculate the GHG Inventory for the Energy Sector. In the Reference approach, production of primary fossil fuels, namely crude produced locally and imported that are used to derive refined products and natural gas for powering the refinery operations serve as the major fuel inputs. However, refined secondary liquid fuels including gasoline, jet kerosene, gas oil/diesel, residual (heavy) fuel oil (bunker C) and LPG that are shipped out of

88 Air Pollution XII


PETROTRIN for local (NP: National Petroleum) or foreign consumption are treated as exports, and as such are not considered as part of PETROTRIN’s emissions. In the Sectoral approach, fossil fuel consumption for the pertinent sub-sectors, namely energy industries, transport, agriculture, forestry and fishing and other (grounds maintenance) are considered. In PETROTRIN’s operations, fuel consumption by the manufacturing and construction, institutional and commercial, residential and international bunkers sub-sectors are considered to be non-existent or minimal at least and as such are not included in the calculations. Similarly for the non-CO2 emissions, only the energy industries, transport, agriculture, forestry and fishing and other (grounds maintenance) sub-sectors are considered. Furthermore, CH4 emissions from oil and gas exploration and refining activities, CO, NOx, NMVOC and SO2 emissions from oil refining activities and NMVOC emissions from oil storage and handling activities are also estimated. In using the IPCC methodology for estimating CO2 and non-CO2 emissions and removals, activity data are extracted from the different operating units of PETROTRIN for the ten years, namely 1990 to 1999, inclusively. For the liquid fuels (crude and refined products) fuel quantities (barrels, litres, gallons) are standardized and converted to kilotonnes (kt) by integrating the specific gravity of each fuel type, so as to facilitate the direct application of the IPCC Conversion Factor (TJ/kt) in order to derive the Apparent Consumption in TJ. Similarly, for natural gas, fuel quantities (cubic feet) are converted to cubic meters and then to TJ using the conversion factor recommended by OLADE [3]. In the vast majority of cases, for lack of company-specific data, the IPCC Tier 1 methodology using the Default Values of the Conversion, Emission and Carbon Oxidation factors, when available, are used. In most instances, default values are extracted from countries of similar characteristics or from the same geographical area.

2.2 Industrial sector

PETROTRIN is mainly an energy company involved in oil and gas exploration, production and refining and marketing activities, and as such is not involved in manufacturing or industrial activities so that CO2 emissions from light manufacturing or heavy industries are minimal or non-existent. The consumption of halocarbons for use in air-conditioners and refrigerators is the only industrial activity within PETROTRIN responsible for greenhouse gas emissions. The consumption and use of halocarbons for air-conditioning and refrigeration causes the release of halon gases (HFCs and PFCs), that are powerful GHGs. However, the use of fridges and refrigerators is limited. As for air-conditioning (AC) units installed in offices and fleet cars, records are available for the years 1996 to 1999. However, these AC units are provided and serviced through lease agreements with outside companies and are as such not included.

Air Pollution XII 89


The only activity of relevance then is the use of fixed and portable fire extinguishers containing HFCs. These are included and HFC emissions are estimated. All activity data are company-specific and are obtained from the Fire Services Department of PETROTRIN, but only from one district in the Exploration and Production Department. The data is therefore incomplete in this regard. However, all emission factors were taken as Default Values from the IPCC Workbooks.

2.3 Agriculture sector

PETROTRIN, being essentially an energy company, the agriculture sector is also a marginal sector insofar as the operations of the company are concerned. Agriculture is mainly focused on dairy and non-dairy cattle production through its affiliate PSAEL. Methane (CH4) is the only perceptible greenhouse gas emitted by the Agriculture Sector. CH4 emissions are limited to emissions from Enteric Fermentation and Manure Management from animal stocks. Nitrous Oxide (N2O) emissions from Manure Management are negligible. The IPCC Tier 1 methodology, using company activity data together with default emission factors, is used. Activity data on animal population according to species for CH4 emissions for 1990 to 1999 are obtained from PSAEL. However, emission factors for enteric fermentation and manure management, in the case of CH4, and for manure management, in the case of N2O, were taken as default values from the IPCC Workbooks.

2.4 Land use and forestry sector

PETROTRIN’s land holdings occupy a relatively large area (10.092 kilohectares), of which forest cover accounts for roughly 3%. Since detailed data on Land-Use and Forestry are not available, limited data sets and expert estimations (Forestry Division of PETROTRIN) place total forest acreage, that is anthropogenically-impacted, at 302.5 hectares, consisting mainly of Mixed Hardwoods (78.1 hectares) and Mixed Softwoods (224.4 hectares). The number of Non- Forest Trees, based on forest inventory statistics of PETROTRIN and expert judgment is estimated to be roughly 1,644,104 trees. Furthermore, based on expert judgment, changes in these acreages over the last 20 years have been minimal. Activity data on Species and Areas (hectares) of forest/biomass stocks, on Annual Growth Rate (t dm/ha) of forests and other trees and savannas and on Commercial Harvest (m3) are company-specific and were obtained from the Forestry Division of PETROTRIN. However, Conversion and Emission factors relating to Carbon Fraction, Biomass Conversion/Expansion and Fraction of Biomass Oxidized were taken as Default values from the IPCC Workbooks. Furthermore, where published data was lacking, as for instance carbon fraction and biomass conversion/expansion, these were estimated from comparisons with other countries in the region.



2.5 Waste sector

In the Waste sector of PETROTRIN, greenhouse gas emissions are limited to Methane (CH4) from Solid Waste Disposal Sites (SWDS), to Methane (CH4) emissions from Industrial Wastewater Treatment and to indirect Nitrous Oxide (N2O) emissions from Human Sewage.

2.5.1 Solid waste disposal to landfills Activity data pertaining to Municipal Solid Waste (MSW) disposed to Solid Waste Disposal Sites (SWDSs) are company-specific data obtained from the Refining and Marketing Department of PETROTRIN for 1997, a typical year. In view of the magnitude of CH4 emissions and based on expert judgment, this value did not change significantly from year to year for the period considered and was therefore used for the other years covered in the inventory. However, the IPCC Default values for Methane Correction factor, Fraction of DOC in MSW, Fraction of DOC which Degrades and Fraction of Carbon Released as methane, were used for the estimation of methane emissions from solid waste disposal systems.

2.5.2 Industrial and wastewater treatment Industrial wastewater treatment, which results in methane (CH4) emissions, takes place within PETROTRIN. Industrial wastewater is produced from oil and gas production and refining activities. Yearly volumes (barrels) of treated water are available for 1990 to 1999 for Trinmar and for 1997 to 1999 of the Exploration and Production Department of PETROTRIN. The value for 1997 is substituted for the values for 1990 to 1996 for the Exploration and production unit of PETROTRIN. However, IPCC default values are used for Degradable Organic Carbon (DOC), Methane Correction Factor and Maximum Methane Producing Capacity.

2.5.3 Indirect nitrous oxide emissions from human sewage At all of PETROTRIN’s operations there is a total work force of 5,000 to 6,000 people. Nitrous oxide (N2O) emissions from human sewage are estimated based on total workforce in each year and the per capita protein consumption. This estimate may be high, given the fact that not all sewage is disposed of at the work site. Nitrous oxide (N2O) emissions from Human Sewage were estimated from country-specific data on Population and Per Capita Protein Consumption (kg/person/yr) as obtained from the Central Statistics Department, Government of Trinidad and Tobago. However, the IPCC Default factors for Fraction of Nitrogen in Protein and Emission of N2O were used to estimate the emissions of N2O from Human Sewage.



3 Results

3.1 Energy sector

3.1.1 CO2 emissions from energy combustion Combustion of gaseous fossil fuels for the refinery operations is the main source of CO2 emissions in the Energy Sector at PETROTRIN. Data analyses of CO2 emissions using both the aggregate Reference and differentiated Sectoral approaches are presented in Table 1 for the years 1990 to 1999. Table 1 shows that CO2 emissions vary between 2,547 Gg (1993) and 7,465 Gg (1998) according to the Reference approach and between 1,550 Gg (1997) and 7,485 Gg according to the Sectoral approach. The Reference and Sectoral approaches seem to vary by 0.03% (1999) and by up to 86.9% (1993). This difference can be attributed to several factors, including transport and refining losses of crude, underestimation and improper records of annual stock changes, not to mention accuracy of the production and refined products records. In 1999, when the records seem to be accurate, both the Reference and Sectoral approaches agree very closely. However, in the other years and in 1993 in particular, it would seem that the quantities of the refined products are grossly underestimated (Table 1). Also, the data for stock changes are not available for all years and all fuels, and where available, are for the fiscal year (October to September) and not the calendar year (January to December).

Table 1: CO2 emissions/removals (Gg) : reference and sectoral methods.

Year Reference Sectoral Difference

(Gg CO2) (Gg CO2) (Gg CO2) %

1990 6389 3321 3068 31,59 1991 5070 3375 1695 20,07 1992 4425 1995 2430 37,85 1993 2547 334 2213 76,81 1994 4481 1887 2594 40,73 1995 4381 2570 1811 26,05 1996 5312 2489 2823 36,18 1997 4709 1550 3159 50,47 1998 7465 4252 3213 27,42 1999 3213 3212 1 0,01

Difference = (Reference - Sectoral)/(Reference + Sectoral) x 100 Within the Energy Sector, CO2 emissions derive almost exclusively from the Energy Industries sub-sector: combustion of liquid (gas/diesel oil) and gaseous (natural gas) fossil fuels in refinery operations account for more than 99% of total CO2 emissions, for all years. Relatively much smaller amounts of CO2 emissions derive from the transportation and navigation (« 1%), the agriculture forestry and fishing (« 1%) and other (grounds maintenance) (« 1%) sub-sectors.



CO2 emissions from the Commercial/Institutional, the Manufacturing Industries and Construction, the Residential and the International Bunkers sub-sectors are non-existent, these not forming part of PETROTRIN’s sphere of activities. Furthermore, the emissions from the refined products that are exported by land and sea are not credited to PETROTRIN. However, the potential CO2 emissions from these products can be quite high. For instance in 1999, potential CO2 emissions are: gasoline (3,906 Gg), jet-kerosene (1,914 Gg), other kerosene (2,508 Gg), gas/diesel/oil (5,249 Gg), residual fuel oil (7,509 Gg), LPG (432 Gg), bitumen (91 Gg), lubes (91 Gg) and other oil (4 Gg) (Figure 1).

Figure 1: Potential CO2 emissions from refined products for the period 1990-1999.

3.1.2 Non-CO2 emissions Non-CO2 emissions of Methane (CH4), Nitrous Oxide (N2O), Nitrogen Oxides (NOx), None-Methane Volatile Organic Compounds (NMVOC) and Sulphur Dioxide (SO2) derive mainly from the combustion of gaseous and liquid fossil fuels in the energy industries and transport sub-sectors. Of the non-CO2 gases, the NMVOC emissions, though relatively small are the highest ranging from 22.1 Gg in 1992 to 43.9 Gg in 1999 (Table 2). Next in importance amongst the non-CO2 gases is CH4, with emissions ranging from 2.3 Gg in 1993 to 23.0 Gg in1998 (Table 2). Then come emissions of NOx, that derive from both the energy industries and transportation and navigation sub-



sectors, with emissions ranging from 5.1 Gg in 1994 to 17.7 Gg in 1998 (Table 2). Carbon Monoxide (CO), that also derive from the from both the energy industries and transportation and navigation sub-sectors is the next important non-CO2 gas, with emissions ranging from 1.0 Gg in 1992 to 6.4 Gg in 1999 (Table 2). SO2 emissions, also a GHG with negative forcing potential, range from 3.7 Gg in 1992 to 9.0 Gg in 1999 (Table 2). Finally, N20 emissions are insignificantly small, being less than 1 Gg in all years (Table 2).

Table 2: Non-CO2 emissions (Gg) : energy sector (1990-1999).

Year 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 CH4 18.02 9.81 10.74 2.37 10.25 5.40 4.86 5.75 23.03 14.21 N2O 0.006 0.004 0.003 0.003 0.003 0.006 0.007 0.005 0.009 0.003 NOX 9.25 7.59 5.281 6.789 5.09 12.61 12.33 9.677 17.66 8.956 CO 1.842 1.438 1.032 4.351 1.147 5.302 5.195 4.748 6.298 6.443 NMVOC 25.66 24.99 22.11 25.13 31.52 32.89 32.34 26.06 41.75 43.91 SO2 4.265 6.743 3.697 4.101 5.284 5.284 5.284 6.505 7.819 9.01

3.2 Industrial sector

Under the UNFCCC convention, only HFC, PFC and SF6 emissions are required to be reported, the other halocarbons being covered by the Montreal protocol. Halocarbon emissions from HFC Consumption for portable fire extinguishers are reported for 1990 to 1999 for PETROTRIN. HFC emissions are significantly small (0.02 Gg) for all years considered and are mainly due to Halocarbon Consumption for fixed and portable fire extinguishers.

3.3 Agriculture sector

From 1990 to 1999, total annual CH4 emissions from Domestic Livestock varied between 0.005 Gg (1990) and 0.042 Gg (1991), the great majority (» 97%) coming from Enteric Fermentation, the remainder coming from Manure Management (Table 3).

Table 3: Methane emissions (Gg) from animal stocks: agriculture sector.

Year Enteric Fermentation Manure Management Total 1990 0.03965 0.00112 0.005 1991 0.04081 0.00115 0.042 1992 0.03881 0.001115 0.0309 1993 0.04018 0.0016 0.04178 1994 0.03801 0.001112 0.0391 1995 0.038133 0.001133 0.0393 1996 0.027892 0.000801 0.0287 1997 0.02922 0.000844 0.0301 1998 0.0308 0.000883 0.0317 1999 0.0272 0.000776 0.028



3.4 Land use and forestry sector

3.4.1 CO2 emissions / removals CO2 Emissions and Removals from the Land Use Change and Forestry sector derive from depletion, followed by regrowth, of forest and other woody biomass stocks through clearing and logging and activities related to oil and gas exploration, leading to removals of CO2, through carbon uptake and sequestration. On the other hand, conversion of forests and grasslands for oil and gas exploration activities result in small emissions due to decay of biomass. The data analyzed for PETROTRIN for the years 1990 to 1999 show a Removal of CO2 of 129 Gg of CO2 due to growth Changes in Forest and Other Woody Biomass Stocks, anthropogenically impacted. This value does not change from year to year, since the forest acreages and growth rates do not change significantly from year to year. Because of the lack of reliable data, Removal of CO2 due to regrowth by the Abandonment of Managed Lands is not estimated. Besides, based on local expert judgment, this activity has been minimal, at least over the last 20 years, and emissions if any, would be insignificantly small. On the other hand, Forest and Grassland Conversions account for only about 1 Gg of CO2 emitted through decay of biomass. This results in a Net Removal (Sink) of 128 Gg of CO2 from Land Use Change and Forestry within PETROTRIN.

3.4.2 Non-CO2 emissions On account of the limited land area (10.092 kilohectares) and insignificant amounts of forest clearing over the last several decades at PETROTRIN, trace gas emissions of Methane (CH4), Nitrous Oxide (N2O) and Nitrogen Oxides (NOx) due to burning of biomass are negligible and as such are not considered.

3.5 Waste sector

3.5.1 CH4 emissions from solid waste disposal Data analyses using the above methodology provide Net Annual Methane Emissions from Solid Waste Disposal Sites of slightly more than 1 Gg of CH4 for all years for PETROTRIN (Table 4). This value, though based on a 1997 study is estimated to be representative of the other years covered in the inventory.

Table 4: Methane and nitrous oxide (Gg) emissions from the waste sector for the period 1990-1999.

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Year

Emission

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

CH4/ N2O

Solid Waste 1.137/0 1.14/0 1.14/0 1.14/0 1.36/0 1.36/0 1.14/0 1.14/0 1.14/0 1.14/0

Waste-water 0.909/0 0.94/0 0.25/0 0.29/0 1.3/0 1.17/0 1.2/0 1.17/0 1.21/0 1.13/0

Human Sewage 0/0.006 0/0.01 0/0.004 0/0.01 0/0.005 0/0.005 0/0.005 0/0.005 0/0.01 0/0.01



3.5.2 CH4 emissions from wastewater treatment Methane emissions from industrial wastewater treatment ranged from 0.25 Gg of CH4 in 1992 to 1.3 Gg of CH4 in 1994 (Table 4).

3.5.3 N2O emissions from human sewage Nitrous Oxide (N2O) emissions in PETROTRIN are very low and are estimated to vary between 0.004 Gg in 1992 and 0.01 Gg in 1993 and 1998 (Table 4).

4 Summary of emissions and removals

4.1 Summary of CO2 emissions and removals

A summary of the major Emissions by Sources and Removals by Sinks of CO2 on a sector-by-sector basis for PETROTRIN for the years 1990 to 1999 is provided in Table 5. It is evident in Table 5 that the dominant source of CO2 emissions is from the Energy sector, which not surprisingly, virtually accounts for all of the net CO2 emissions, with CO2 emissions ranging from 1,887 Gg (1994) to 4,253 Gg (1998). The Land Use and Forestry sector, which is also responsible for a very small amount of CO2 emissions, through Forest and Grassland Conversion (« 1 Gg), is a Net Sink with a Net removal of (-) 127 to 128 Gg CO2 due to Growth Changes in Forest and Other Woody Biomass Stock. (Table 5).

Table 5: Carbon dioxide emissions (Gg) from each sector for the period 1990-1999.

Sectors 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Energy 3321 3375 1995 334 1887 2570 2489 1550 4253 3212 Industrial Processes 0 0 0 0 0 0 0 0 0 0

Agriculture 0 0 0 0 0 0 0 0 0 0 Land-Use Change & Forestry

-127 -127 -127 -127 -127 -127 -128 -128 -128 -128

Waste 0 0 0 0 0 0 0 0 0 0

4.2 Summary of non-CO2 emissions and removals

Comparatively smaller amounts of non- CO2 greenhouse gases are emitted or removed in PETROTRIN for the years 1990 to 1999. Table 6, which provides non- CO2 emissions for a typical year (1999), shows that CH4 emissions are the most significant and derive mainly from the energy sector. For the years 1990 to 1999, CH4 emissions range from 4.9 Gg (1996) to 23.0 Gg (1998). Smaller amounts of CH4 emissions derive from the waste sector, with values ranging from « 1 Gg (1993) to 8.7 Gg (1998). Insignificantly small amounts of CH4 emissions also derive from Enteric Fermentation and Manure Management (« 1 Gg CH4) from the Agriculture Sector. N2O emissions also derive mainly from the energy sector, with values ranging from 22.1 Gg (1992) to 43.9 Gg (1999) of N2O. Very insignificant amounts (« 1 Gg) of N2O emissions also derive from



Human Sewage in the Waste Sector. NOX emissions also derive almost exclusively from the Energy Sector, as emissions in the energy Industries and Transport sub-sectors. NOX emissions range from 3.7 Gg (1992) to 9.3 Gg (1990). Similarly CO emissions derive mainly from the Energy Sector from the Energy Industries and Transport sub-sectors, with values ranging from 1.0 Gg (1992) to 6.4 Gg (1999). NMVOC emissions also derive mainly from fuel combustion in the Energy sector with values ranging from 22.1 Gg (1992) to 43.9 Gg (1999). The only other significant GHG in PETROTRIN is SO2, a GHG with negative forcing, which is emitted through the combustion of Gas/Diesel Oil and Residual Fuel Oil in the Energy sector. SO2 emissions range from 3.7 Gg (1992) to 9.0 Gg (1999) (Table 6). Finally, HFCs are emitted exclusively from the Industrial Sector from halons use in portable and fixed fire extinguishers. However HFC emissions are insignificantly small being « 1 Gg for all years (Table 6).

Table 6: Non-carbon dioxide emissions for petrotrin sectoral approach 1999.

Sectors CH4 N2O NOX CO NMVOC SO2 HFC’s PFC’s SF6 Energy 14.208 0.003 8.956 6.443 43.905 9.01 0 0 0

Ind. Process 0 0 0 0 0.003 0 0.02 0 0 Agriculture 0.028 0 0 0 0 0 0 0 0

LUCF 0 0 0 0 0 0 0 0 0 Waste 8.651 0.005 0 0 0 0 0 0 0

5 Summary and conclusions

It transpires from the above, that, not including Memo Items, PETROTRIN is a net emitter of CO2. Net CO2 emissions that derive from the Energy sector range from 334 Gg (1993) to 4, 253 Gg (1998). Net CO2 removals on the other hand, that derive from the Land Use Change and forestry sector is relatively small, being about 128 Gg (Table 5). Non- CO2 emissions are less and are also due mainly to CH4, N2O, NOx, CO, NMVOC and SO2 emissions from the Energy sector (Table 6). However, the calculations of sources and sinks of GHG’s for the different sectors, as described above, incorporate several levels of uncertainty with respect to both the company activity data and the various conversion and emission factors. For the energy sector, by far the most important, the main source of uncertainty is the partitioning of the total fuels used in the different sub-sectors. This somewhat limits the results of the Sectoral Approach. However, for the Reference Approach, where the total fuels used are lumped together, there is lesser or very little uncertainty. For the energy sector, total company activity data for HFC and PFC are extrapolated from a single district in the Exploration and Production Department, and this may limit the accuracy of the data. A limited amount of uncertainty is encountered in the agriculture sector. Company Statistics (PSAEL) provided reliable activity data on animal populations and manure management characteristics. In the land use and forestry sector, it was assumed that all of PETROTRIN,s forest lands were anthropogenically impacted. Although, there was a detailed inventory of non-forest trees, there was



some estimation involved in the number of non-forested trees. Finally, in the waste sector, in the estimation of CH4 emissions from solid waste disposal, the methodology utilizes data for a single year and for one unit representing about one quarter of the municipal solid waste generated by the company. In the case of N2O emissions from human sewage, company yearly population was estimated and the assumption that all sewage from employees is attributed to company facilities may be erroneous. Furthermore the default value for per capita protein consumption may not be representative. In the estimation of methane emissions from wastewater treatment from industrial sources, namely from production and refining activities at PETROTRIN, data for 1990 to 1996 had to be estimated. Also, the preceding sections deal with Direct GHG emissions from the Operations of PETROTRIN, including those of Joint ventures, such as Trinmar and PSAEL. However, as recommended by the American Petroleum Institute (API, 2001), Indirect Emissions from Imported and Exported Electricity and Steam and Emissions from Contractor Activities, should also be included in a Comprehensive Emissions Inventory. CO2 sequestration is not considered as a removal factor for CO2 for lack of data. But large quantities of CO2 are pumped into drilling wells to increase pressure and flow. Although the quantities injected may be known, no data on the amount that resurfaces is available.

References

[1] American Petroleum Institute, Compendium of Greenhouse Gas Emissions Estimation Methodologies for the Oil and Gas Industry, 2001.

[2] Houghton, J.T., Meira Filho, L.G., Lim, B., Tréanton, K., Mamaty, I., Bonduki, Y., Griggs, D.J. & B.A. Callender, B.A. (editors), Intergovernmental Panel on Climate Change (IPCC): Greenhouse Gas Inventory Reporting Instructions. Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. Volumes 1, 2 and 3.

[3] OLADE (Organizacion Latinoamericano de Energia), 2003. www.olade.org. [4] Penman, J., Kruger, D., Galbally, I., Hiraishi, T., Nyenzi, B., Emmanuel, S.,

Buenida, L., Hoppaus, R., Martinsen, T., Meijer, J., Miwa, K. & and Tanabe, K. Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories, 510 p, 2000.

[5] Singh, B. & El Fouladi, A., Simplified Methodologies for Calculating Greenhouse Gas Inventories using the IPCC Guidelines. Training Manual, 160 p., 2001.



Greenhouse gas inventory of the Petroleum Company of ......takes place within PETROTRIN. Industrial...

Documents

Transcript of Greenhouse gas inventory of the Petroleum Company of ......takes place within PETROTRIN. Industrial...