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Fossil fuel use and CO2 emissions in Korea: NEAT approach
Resources, Conservation and Recycling 45 (2005) 295–309
Fossil fuel use and CO2 emissions in Korea: NEAT approach Hi-chun Park ∗ Department of Economics, Inha University, 253 Yonghyun-Dong, Nam-Ku, Incheon 402-751, Republic of Korea Available online 15 August 2005
Abstract Carbon accounting is a key issue in the discussions on global warming/CO2 mitigation. This paper applies both the intergovernmental panel on climate change-reference approach (IPCC-RA) and the non-energy use emission accounting tables (NEAT) model, a material flow analysis, to estimate the carbon storage originating from the non-energy use as to assess the carbon release from the use of fossil fuels in Korea for the years 1999 and 2000. The current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate CO2 emissions. This is because the gross naphtha deliveries are currently considered as feedstock use. The estimation after correction of the non-energy use statistics shows, however, that the carbon storage calculated according to the IPCC-RA are lower than those calculated using the NEAT model. This is because the IPCC default storage fraction for naphtha used in Korea seems to be too low for the Korean petrochemical production structure. A by-product of this study is the identification of a double counting of naphtha consumption in the amount of the backflows to refineries in the Korean energy balance which led to a four-year project to revise the energy balances back to 1990. This paper shows that a material flow analysis like the NEAT model can provide a better basis for estimation of CO2 emissions of the non-energy use and with it that of the fossil fuel use than the current IPCC-RA. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. © 2005 Elsevier B.V. All rights reserved. Keywords: Non-energy use; Carbon accounting; CO2 emissions; Korean petrochemical industry; Material flow analysis
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1. Introduction The combustion of fossil fuels results in carbon release (CO2 emissions), which is the major source of anthropogenic CO2 emissions according to current knowledge. Fossil fuels are also used for non-energy use purposed, either directly (e.g. the use of some refinery products like lubricants) or as feedstock for the manufacture of synthetic organic products. Some of these products (e.g. plastics) only lead to Greenhouse gas (GHG) emissions during incineration of post-consumer waste or do not lead to GHG emissions at all (e.g. bitumen or landfilled plastics). We refer to these chemicals as chemicals that are not oxidized during use (NODU). In contrast, the carbon embedded in another group of products, such as detergents, some solvents and part of lubricants is released to the atmosphere partially or fully during the use phase of the chemicals. We refer to these chemicals as products that are oxidized during use (ODU). ODU products are assumed to lead to CO2 emissions directly within the inventory year. As all commodities, ODU products are traded and hence the products used in a given country are typically partly produced domestically and partly imported. Emission inventories should correct for this international trade in order to calculate the correct GHG emissions. NODU products only lead to GHG emissions during the incineration of post consumer waste. As such carbon storage in NODU products only contributes to global warming/climate change if the products are incinerated. A country’s CO2 emissions from the use of fossil fuels can be estimated as the difference between the carbon content of the total fuel use and the carbon storage. As the total fossil fuel use can be calculated relative easily from the national energy balances1 , the main problem rests on the estimation of the carbon storage from the non-energy use. The non-energy use, predominantly feedstock consumption, amounted to about 6.5% of the total primary energy supply (TPES) for 2000 in the European Union. These shares are higher in the Netherlands and Korea with about 13.5 and 14.1%, respectively (Neelis et al., 2005). Thus, it is particularly important to estimate exactly the carbon storage for countries with a large share of non-energy use compared to the total national fossil fuel use. These estimates can have importance in discussions on CO2 emissions. For instance, if carbon taxes are introduced, underestimation of the carbon storage will adversely affect the petrochemical industry. On the other side, overestimation of the carbon storage will mean wrong incentives for this industry. This paper calculates the carbon storage from the non-energy use to assess the CO2 emissions from the use of fossil fuels in Korea for the years 1999 and 2000. First, accounting methods for carbon storage are discussed in Section 2. Section 3 gives a brief overview of the Korean petrochemical industry. Sections 4 and 5 estimate the carbon storage from the non-energy use in Korea by using the IPCC-RA default storage fractions and the NEAT model, respectively. Section 6 compares the total CO2 emissions estimated by using various models. At the end some conclusions will be drawn.
1
Required is a sound energy balance for fossil fuel consumption.
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2. Accounting approaches for carbon storage Well known are the reference approach (RA) and sectoral or standard approach (SA) according to the IPCC guidelines (IPCC/IEA/OECD/UNEP, 1997). The IPCC-RA calculates the CO2 emissions by deducting the carbon storage from the non-energy use from a country’s total fossil fuel use. The IPCC-SA adds up emissions for individual activities (or source categories), such as energy use, industrial processes, solvent use and waste. In contrast, the NEAT model traces carbon storage in petrochemical processes and flows within a country’s organic/petrochemical complex based on material flow analysis. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. The IPCC-SA will not be elaborated further, as only the IPCC-RA and the NEAT model will be compared with each other. 2.1. The IPCC reference approach The IPCC guidelines indicate that storage of fossil carbon in synthetic organic materials and products should be taken into account. They make a distinction between carbon storage in products over long periods and short-term release of carbon.2 Only long-term storage originating from the non-energy use should be subtracted from annual national CO2 emissions due to the use of fossil fuels. Hence, emissions from short-life (less than 20 years in general) materials and incineration of long-life materials do not belong to the carbon storage. They are considered as CO2 emissions. According to the IPCC-RA, the carbon storage can be calculated by multiplying the non-energy use of fuels QNEU (given as lower heating value in GJ) by the respective storage fraction P and the emission factor EF (kg CO2 /GJ) as follows: storage EIPCC = {QNEU Pi EFi } (1) i
with i indicating the type of fuel. The IPCC guidelines (IPCC/IEA/OECD/UNEP, 1997) provide default values for Pi as given in Table 6. Alternatively, the carbon release can be calculated as the difference between the total emissions and the carbon storage of fuels with the following formula: release EIPCC = {QNEU,i (1 − Pi )EFi } (2) i
Limitations of the calculation under the IPCC reference approach can be summarized as follows: • The default carbon storage fractions P that are proposed for the IPCC-RA are based on work done by Marland and Rotty for 1950–1982 in the US (Marland and Rotty, 1984). These might not hold for other countries in consideration. For instance, the storage 2 This study distinguishes between ODU and NODU products instead of short-life and long-life products as to ensure a clear allocation of product related emissions to the IPCC source categories. For a more detailed discussion, reference is made to Neelis et al., 2005.
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fraction 0.75 for naphtha is rather low for countries like Korea, which has a higher production share of NODU petrochemicals. On top of this, Marland and Rotty’s storage fractions represent the share of the non-energy use of a fuel, which remains unoxidised for long periods of time. The use of such fractions in the IPCC-RA leads to CO2 emission estimation comprising fuel combustion, waste incineration and (autonomous) product oxidation. In contrast, the purpose of the IPCC-RA is generally regarded as a validation tool for CO2 emissions from fuel combustion only (Neelis et al., 2005). • Default values of storage fractions P and emission factors EF are not given for all types of fuels. • The IPCC-RA does not consider the trade with petrochemicals. This can have consequences to the results of countries with large net imports or net exports. • The IPCC-RA is based on non-energy use data from the energy statistics. While these data are well-suited for energy accounting, they are less suited for carbon accounting. To overcome some of these limitations, a material flow analysis like the NEAT model can be applied. 2.2. The NEAT model version 2.0 The non-energy use emission accounting tables (NEAT) model developed by the NEU–CO2 network estimates carbon storage based on a material flow analysis of the petrochemical sector. The model contains the conversion routes from 22 basic chemicals to 55 intermediate and final products (Table 4). The total consumption of final products and the consumption of intermediates and basic chemicals for other derivatives is divided into ODU and NODU applications. For the consumption of intermediates for other derivatives, the fraction of ODU versus NODU has been based on consumption patterns for intermediates found in literature. The part of the non-energy use, which is stored (i.e. not emitted) in the country of study is calculated as the sum of two elements (see also Neelis et al., 2005): 1. the consumption of NODU products in the country of study, and 2. the net export of all basic chemicals3 , intermediates and final products included in the NEAT model. All flows are converted to CO2 equivalents and carbon yields in the various conversion steps are set to 100%. A sensitivity analysis is included in the NEAT model for the division between ODU and NODU applications.
3. The Korean petrochemical industry The Korean petrochemical industry grew rapidly in the period 1988–2000. Table 1 shows that the production capacities for ethylene, propylene, benzene, xylene, styrene monomer, high density polyethylene (HDPE), terephthalic acid (TPA) increased by 6–13 times. For 3 Excluding the non-energy use refinery and coke oven products for which the trade is already accounted for in the energy statistics.
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Table 1 Capacity trend of Korean petrochemical plants for 1988–2000 (in kilotons)
Ethylene Propylene Benzene Toluene Xylene P-xylene Styrene monomer HDPE Polypropylene Polystyrene PVC TPA Carbon black
1988
1990
1992
1996
2000
505 268 309 292 338 160 230 280 660 373 530 500 205
1155 625 558 418 758 560 675 743 805 787 610 1160 250
3255 1895 1241 751 1527 560 1135 1173 1310 925 710 1210 340
4340 2602 1633 1195 2286 1400 1645 1503 2105 1036 1045 3110 530
5150 3476 2587 1910 2288 3280 2255 1792 2518 1112 1240 4470 530
Source: Korea Petrochemical Industry Association, Petrochemical Annual 2001, Seoul.
instance, the number of naphtha crackers rose from two in 1988 to seven in 2000. As a result, the naphtha cracking capacities increased from 0.505 Mt (million tons) to 5.150 Mt. In comparison, only the USA (27.014 Mt), Japan (7.410 Mt) and Germany (5.215 Mt) had higher cracking capacities than Korea in 2000. The Korean petrochemical industry uses almost exclusively naphtha as feedstock for its high severity naphtha cracker in which about 31% of the production is ultimate ethylene yield. Korea’s gross exports of petrochemicals amounted to US$ 9.4 billion in 2000. Among the most important exported petrochemicals were polypropylene, HDPE, low density polyethylene (LDPE), acrylonitrile butadiene styrene (ABS), styrene monomer (SM), polystyrene, TPA, etc. Gross imports of petrochemicals had a value of US$ 4.5 billion in 2000. Major importing chemicals were p-xylene, ethylene glycol, caprolactam, xylene, etc., as shown in Table 2. Korea is hence a net exporter of petrochemicals in the amount of US$ 4.9 billion. Table 2 Korean trade with major petrochemicals in 2000 Exports
Polypropylene ABS HDPE Styrene momomer Polystyrene LDPE TPA P-xylene Toluene PVC
Imports
Million $
Mt
808 712 683 646 600 573 563 421 323 281
1.328 0.592 1.022 0.894 0.602 0.829 1.253 0.987 1.011 0.410
Ethylene glycol P-xylene Caprolactam Xylene Ethylenedichloride Methanol Styrene momomer – – –
Source: Korea Petrochemical Industry Association, Petrochemical Annual 2001, Seoul.
Million $
Mt
400 385 343 263 185 181 165 – – –
0.710 0.845 0.244 0.784 0.512 1.091 0.218 – – –
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The Korean petrochemical industry produced in 2000 petrochemicals in the amount of US$ 20.455 billion which corresponded to 45.8 and 12% of the production in the chemical industry and in the manufacturing industry, respectively. However, it was relatively less value added intensive and less manpower intensive than other sectors of the manufacturing industry. The petrochemical industry’s contribution to the manufacturing industry’s value added and employment were hence only 3.1 and 0.9%, respectively.
4. Carbon storage with the IPCC-RA default storage fractions To estimate the carbon storage according to the IPCC-RA, it is necessary to know the amounts of fossil fuels by types used as feedstock for the manufacture of petrochemicals (non-energy use of fossil fuels). The Korean energy balances list only naphtha, asphalt/bitumen, lubricants, waxes and paraffins, petroleum coke and solvent as non-energy use, while, in reality, the Korean petrochemical industry uses also LPG, kerosene, fuel oil and coal as feedstock. There is hence need to improve the Korean non-energy use statistics. Those feedstocks, which are not listed in the Korean energy balances should be collected and reported. This would ultimately lead to more accurate results for the IPCC-RA. According to investigations by the author LPG, kerosene, fuel oil and coal are used for the following purposes: LPG, mostly butane, is required to produce synthetic gas, which is in turn needed by some petrochemical firms for the production of maleic anhydride (MA). Kerosene is converted to normal paraffin for the production of alkyl benzene which is needed in turn for the detergent production. Propylene is produced as by-product (4–5%) in the residual fluidized catalytic cracking (RFCC), which converts fuel oil to gasoline. And pitch, naphthalene, creosote oil and coal tars are produced from coal. For instance, coal tars are converted to carbon black. Information on LPG was collected from the Korea National Oil Corporation. In the case of coal tars, information on their consumption and international trade was gathered from the sole producer of carbon black in Korea. And information on kerosene and fuel oil were provided from concerned firms. All this data is listed in Table 6 for 2000.4 In the case of naphtha, by far the largest feedstock in the petrochemical industry, the Korean energy balances give only information in gross terms. According to it, Korea used naphtha in the amount of 1219.6 PJ (29.1 Mtoe, at 41.9 PJ/Mt) which is equivalent to 15.1% of the total energy consumption of 8075.7 PJ (192.9 Mtoe) in primary energy terms (TPES). However, this value includes the backflows from steam crackers to refineries (external naphtha backflows) and the fuel by-products used as process fuel in the petrochemical sector (internal naphtha backflows). This paper estimates the external and internal naphtha backflows by analyzing material balances of naphtha using companies. There were six naphtha steam crackers or naphtha cracking centers (NCC) with aromatics recovery (BTX), four refineries with aromatics recoveries (BTX), one refinery with steam cracking and aromatics recovery (NCC, BTX) and eight other petrochemical companies with a total net naphtha consumption of 25.619 Mt (228.007 Mbbl) in 2000. 4 In order not to overload this paper with large tables the ones for the year 1999 are omitted. These are available on request from the author.
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On the one hand, Korean naphtha steam crackers (NCC, BTX) extract apart from basic chemicals, such as ethylene, propylene, pyrolysis gasoline (PG) and styrene hydrogen, methane, propane, fuel oil and mixed C4 which can be used all or partly as process fuel. They operate BTX plants to extract benzene (ca. 26.6% of the PG input), toluene (ca. 15.9%) and xylene (8.5%) from PG (ca. 20% of the naphtha input). On the other hand, Korean refineries extract in their BTX plants from naphtha apart from benzene, toluene, xylene and para-xylene LPG, heavy aromatics, C5 and C6 naphtha, etc., which can be also used as fuel. Thus, it is necessary to make a correction for that part of naphtha, which is used as fuel internally (process fuel) as well as externally (by-products returned to refineries for the production of gasoline, for instance).5 Korean petrochemical companies report quarterly their material balances to the government to get reimbursed the “petroleum tax” paid on naphtha used as feedstock and process fuel. In Korea apart from a 5% customs duty a petroleum tax of Won 14 per liter (Won 2226 or US$ 1.78 per barrel) is levied on imports of crude oil and petroleum products. This tax is used to finance strategic petroleum stockpiling and development of new and renewable energy. Table 3 shows that domestically produced and imported naphtha in the amount of 16.535 Mt were delivered to six steam crackers (NCC, BTX) in 2000. The steam cracking resulted in the extraction of 11.997 Mt high value petrochemicals (72.6%) and 4.538 Mt by-products (27.4%). From these by-products 3.591 Mt (21.7% of gross naphtha deliveries) were used as process fuel within the steam cracker (internal backflows). And 0.686 Mt (4.2%) were sold in forms of LPG on the market. As the remaining 0.261 Mt (1.6%) was sent back to refineries, the net naphtha consumption by six steam crackers was 16.274 Mt (98.4%). Refineries operate BTX plants to extract benzene, toluene and xylene from naphtha. The extraction of these petrochemicals amounted to 3.524 Mt or 38.2% of naphtha input of 9.223 Mt in 2000. And 0.808 Mt by-products (8.8%) were used as process fuel. The remaining by-products of 4.891 Mt were sent back to the refining sector. Table 3 lists one refinery, which also operates two NCC. It extracted 3.393 Mt petrochemicals. The by-products were partly sent back to the refining sector and partly used as process fuel within the steam cracker. As the entire petrochemical sector returned by-products of 7.253 Mt (22.1%) out of the gross naphtha deliveries 32.871 Mt to the refineries for the production of gasoline, only the balance 25.619 Mt should be considered as the net naphtha consumption (Table 3). Furthermore, the petrochemical sector used 5.421 Mt by-products (16.5%) as process fuel and sold 0.686 Mt by-products (2.1%) in forms of LPG on the market. The gross naphtha consumption of the Korean petrochemical industry with 1377.3 PJ is much bigger than that of the Korean energy balance with 1219.7 PJ. As we are unable to revise the Korean energy balance, we will use the official gross naphtha consumption figure but consider only 59.4% of the gross naphtha consumption given in the Korean energy balance as non-energy use or feedstock. A by-product of this study is the identification of some inconsistencies in the concept of the Korean energy balance, which led to a 4-year project to revise the energy balances back 5 Energy balances in some countries consider the internal naphtha backflows as non-energy use. A detailed discussion on steam cracking operation, reference is made to Section 4 in Neelis et al. (2005).
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Gross naphtha input Backflows to refineries (in percentage of gross input) Net naphtha consumption (in % of gross input) Feedstock use (in % of gross input) Fuel use & losses (in % of gross input) LPG sales on the market (in % of gross input)
NCC, BTX (6)
Refineries BTX (4)
Refinery with NCC (1)
Others (8)
Total (19)
16.535 0.261 (1.6) 16.274 (98.4) 11.997 (72.6) 3.591 (21.7) 0.686 (4.2)
9.223 4.891 (53) 4.332 (47) 3.524 (38.2) 0.808 (8.8)
6.330 2.097 (33.1) 4.233 (66.9) 3.393 (53.6) 0.839 (13.3)
0.783 0.003 (0.4) 0.780 (99.6) 0.597 (76.2) 0.183 (23.4)
32.871 7.253 (22.1) 25.619 (77.9) 19.511 (59.4) 5.421 (16.5) 0.686 (2.1)
Source: quarterly reports (including material balances) of naphtha consuming petrochemical companies.
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Table 3 Korean naphtha flow in 2000, a survey result in Mt
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to 1990. This study has discovered a big discrepancy between the carbon storages assessed according to IPCC-RA and by the NEAT model. A detailed analysis on the Korean naphtha flow has shown that among other things the naphtha backflows to refineries have been double counted in the Korean energy balance, which forms the basis of the IPCC-RA calculation. In fact, the double counting of naphtha consumption stems from a misconception in the current Korean energy balance framework, which does not have any transformation balance for the petroleum sector. Gross deliveries of petroleum products by the domestic refineries are reported as ‘petroleum products’ of the row ‘imports’ in the total primary energy supply (TPES) balance of the Korean energy balance. Crude oil imports do not appear in the energy balance. The TPES balance which has also the function of petroleum transformation in the current energy balance cannot consider any flows between the petroleum sector and the petrochemical sector. A preliminary revision of the Korean energy balance for 2000 reveals that the TPES of the current energy balance is overestimated by 3% (5.565 Mtoe = 233 PJ) from 187.3 Mtoe (7842.7 PJ, revised) to 192.9 Mtoe (8075.7 PJ). This overestimation is mostly due to the double counting of the naphtha consumption in the amount of the external naphtha backflows of 5.390 Mtoe (225.7 PJ).
5. Carbon storage with the NEAT model 5.1. Data To run this model, it is essential to have production and trade data of basic chemicals, intermediates and products as listed in Table 4. The Korea Petrochemical Industry Association publishes annually data on productions for benzene, butadiene, other C4, carbon black, ethylene, propylene, toluene, xylenes (total, o-xylene, p-xylene), acetic acid, acetone, acrylonitrile, butanol, caprolactam, DMT, ethanol, ethylenedichloride, ethylene glycol, octanol, phenol, phthalic anhydride, propylene oxide, styrene, TPA, TDI, VCM, ABS, BR, polyethylene, polypropylene, polystyrene, polyurethane, PVC and SBR (KPIA, 2002). Those for bitumen, petroleum coke and waxes and paraffins are provided by the Korea National Oil Corporation. Data on methanol, naphthalene, m-xylene, acrylic acid, adipic acid, aniline, bisphenol A, cumene, ethylene oxide, formaldehyde, MTBE, EPDM, epoxy resin, phenolic resin, polycarbonate, polyvinylacetate, SAN and unsaturated polyester are taken from the publication of the Chemical Research Institute, a private consulting firm (Chemical Research Institute, 2001, 2003). Data on acetylene, ammonia, lubricants, pitch, creosote oil, other tar products, cyclohexanone, ethylbenzene, i-propanol, melaminformaldehyde resin, PET, urea formaldehyde resin and polyacetals were gathered directly from petrochemical producers or their associations. Trade data are gathered partly from the same sources as production data and partly from the Korea trade statistical database of the Korea international trade association (KITA, http://db.kita.net). One important task of a material flow analysis, such as the NEAT model is the treatment of the use of intermediates in the category “others”. This category includes all types of applications, which have not been elaborated (in some case the total application of products of minor importance “total”). In NEAT, the total assigned to the category “others” is allocated
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Table 4 Korean petrochemical production and trade, 2000 Production [Mt/yr]
Imports [Mt/yr]
Exports [Mt/yr]
Basic chemicals Acetylene Ammonia Benzene Bitumen Butadiene Other C4 Carbon black CO source Ethylene Lubricants Methanol Petroleum coke Pitch Creosote oil Naphthalene Other tar products Propylene Toluene Waxes, paraffins Xylenes (o-, m-, p-, mixed xylene) o-xylene m-xylene p-xylene
0.000 0.448 2.806 2.194 0.730 0.754 0.456 0.400 5.537 0.908 0.000 0.322 0.200 0.080 0.045 0.420 3.602 1.472 0.010 3.549 0.376 0.039 3.135
0.000 0.743 0.236 0.004 0.029 0.000 0.009 0.000 0.099 0.011 1.091 0.000 0.019 0.009 0.000 0.769 0.179 0.000 0.022 0.784 0.013 0.002 0.845
0.000 0.000 0.688 0.514 0.177 0.000 0.127 0.000 0.313 0.090 0.010 0.078 0.200 0.000 0.001 0.211 0.383 1.011 0.007 0.453 0.074 0.003 0.987
Intermediates Acetic acid Acetone Acrylic acid Acrylonitrile Adipic acid Aniline Bisphenol A Butanol Caprolactam Cumene Cyclohexane Cyclohexanone Dimethylterephthalate Ethanol Ethylbenzene Ethylenedichloride Ethylene glycol Ethylene oxide Formaldehyde MTBE Octanol Orthophthalates Phenol
0.389 0.083 0.121 0.357 0.055 0.089 0.038 0.078 0.116 0.081 0.161 0.103 0.135 0.032 2.837 0.590 0.832 0.066 0.450 0.791 0.319 0.510 0.130
0.062 0.028 0.050 0.092 0.030 0.018 0.072 0.010 0.244 0.012 0.056 0.155 0.013 0.096 0.000 0.512 0.710 0.000 0.000 0.052 0.092 0.006 0.017
0.072 0.025 0.065 0.074 0.040 0.000 0.000 0.036 0.000 0.020 0.082 0.000 0.055 0.003 0.000 0.015 0.227 0.000 0.000 0.091 0.079 0.238 0.046
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Table 4 (Continued ) Production [Mt/yr]
Imports [Mt/yr]
Exports [Mt/yr]
Phthalic anhydride (PSA) Polyether-polyols i-Propanol Propylene oxide Styrene Terephthalic acid (TPA) TDI Urea Vinylchloride monomer (VCM)
0.371 0.011 0.043 0.154 2.467 4.291 0.104 0.687 1.329
0.007 0.001 0.025 0.022 0.218 0.005 0.000 0.485 0.031
0.139 0.000 0.008 0.000 0.894 1.253 0.072 0.109 0.175
Products ABS BR EPDM Epoxy resin Melamineformaldehyde resin Phenolic resin Polyacetals Polyacrylates Polyacrylonitrile Polyamide 6,66 Polycarbonate Polyethylene (PE) Polyethyleneterephthalate (PET) Polypropylene (PP) Polystyrene (PS) Polyurethane (PUR) Polyvinylacetate Polyvinylchloride (PVC) SAN Saturated polyester SBR Unsaturated polyester/alkyd resin Urea formaldehyde resin (UF)
0.878 0.171 0.046 0.098 0.024 0.084 0.090 0.119 0.000 0.298 0.073 3.220 0.377 2.347 1.041 0.434 0.016 1.187 0.079 3.216 0.266 0.088 0.001
0.005 0.018 0.002 0.016 0.005 0.026 0.006 0.013 0.000 0.029 0.073 0.058 0.004 0.013 0.015 0.078 0.009 0.031 0.003 0.101 0.021 0.002 0.002
0.592 0.100 0.017 0.049 0.001 0.000 0.063 0.100 0.000 0.061 0.042 1.797 0.021 1.328 0.602 0.196 0.011 0.410 0.061 1.178 0.162 0.013 0.000
59.453
8.512
15.944
Total
Sources: Korea Petrochemical Industry Association, Petrochemical Annual, Chemical Research Institute, Chemical Annual, and own estimates.
to ODU versus NODU products by means of information from literature (see Neelis et al., 2005). 5.2. NEAT results The carbon storage calculated with the NEAT model was 57.2 Mt CO2 for 1999 and 61.4 Mt CO2 for 2000 shown in Table 5. However, there are built-in uncertainties in the NEAT results as the storage due to the consumption of NODU products is for 1999, 34.7 Mt
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Table 5 Comparison of CO2 estimates according to various methods Total use of fossil fuels in CO2 [Mt CO2 ] 1999 2000
Carbon storage from non-energy use [Mt CO2 ] 1999 2000
C02 emissions from use of fossil fuels [Mt CO2 ] 1999 2000
IPCC-RA approacha Statistics uncorrected Statistics corrected IEAb
483.929 483.929
517.634 517.634
70.980 50.003
74.175 52.137
412.949 433.926 413.200
443.463 465.501 444.500
NEAT modelc
483.929
517.634
57.195
61.447
426.734
456.191
a b c
Tables 6 and 7. IEA, CO2 emissions from fuel combustion, 2002 edition. Section 5.2.
CO2 with an uncertainty in the range from 32.9 to 39.3 Mt CO2 and for 2000, 36.1 Mt CO2 with an uncertainty in the range from 34.3 to 39.7 Mt CO2 . The storages calculated with the NEAT model are higher than those according to the IPCC-RA, which was 50.0 and 52.1 Mt CO2 , respectively. This would mean that the IPCC default storage fraction 0.75 for naphtha should not be adequate to assess the CO2 emissions in Korea. As 1% of the naphtha consumption in the Korean petrochemical sector in terms of carbon storage is equivalent to 0.505 Mt CO2 for 1999 and 0.529 Mt CO2 for 2000 and as naphtha accounts for 84.7% of the non-energy use in Korea excluding bitumen, the difference (7.249 Mt CO2 for 1999 and 6.996 Mt CO2 for 2000) between the carbon storage assessed by the NEAT model and according to the IPCC-RA will correspond to 14.4% for 1999 and 13.2% for 2000. As a result, the storage fraction for naphtha should be about 0.88 (0.75 + 0.13). In the case of the Netherlands, 0.82 is used as the storage fraction for naphtha.
6. Total CO2 according to the various methods Once the carbon storage (50 Mt for 1999 and 52.1 Mt for 2000 shown in Table 6) from the non-energy use of fossil fuels are calculated, it is straightforward to estimate the CO2 emissions according to the IPCC-RA (434 Mt for 1999 and 465.5 Mt for 2000) by subtracting the carbon stored from the carbon content of the total national fossil fuel use (483.9 Mt for 1999 and 517.6 Mt for 2000) as shown in Table 7. The change (correction) in the Korean non-energy statistics results in an increase of Korea’s CO2 emissions by 21 Mt from 413 to 434 Mt in 1999 and by 22.1 Mt from 443.4 to 465.5 Mt in 2000. This is because the gross naphtha deliveries are considered as feedstock in the current accounting. As official data for CO2 emissions according to the IPCC-RA are missing, those by the International Energy Agency (IEA) will be compared with the ones assessed with the NEAT model as in Table 5. In fact, Korea’s CO2 emissions 413.2 Mt for 1999 and 444.5 Mt for 2000 estimated by IEA indicate that IEA seems to use similar nonenergy use statistics as the Korean authorities. Thus, the estimates by using the uncorrected non-energy use statistics can be considered as “official” CO2 emissions according to the IPCC-RA.
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Table 6 Estimation of cabon storage in products after correction using the IPCC-RA default storage fractions, Korea, 2000 Non-energy use [PJ]
Storage fraction [%]
Emission factor [Mt CO2 /PJ]
Carbon storage [Mt CO2 ]
Naphtha (energy balances)a Naphtha (corrected)b Lubricantsa Petroleum cokea Bitumen/asphalta Solventa Waxes and paraffinsa Coal tars Kerosene Fuel oilc LPG
1219.636 724.464 35.878 6.801 68.908 4.019 0.419 21.382 9.680 18.330 35.830
75 75 50 75 100 80 80 75 80 80 80
0.0730 0.0730 0.0730 0.1030 0.0770 0.0730 0.0730 0.0939 0.0730 0.0770 0.0660
66.775 39.646 1.309 0.526 5.306 0.235 0.024 1.505 0.565 1.129 1.892
Total (energy balances)
1335.660
–
–
74.175
925.711
–
–
52.137
Total (Corrected) a
Listed in the Korean energy balances. b Backflows to refineries of 265.539 PJ (double counted) and internal backflows of 225.633 PJ (used as process fuel) are excluded. c Amount of the propylene production in residual fluidized catalytic cracking RFCC.
Table 7 Total national fossil fuel use and CO2 emissions in Korea, 2000 Energy carriers
[PJ]
Carbon emissions factor [Mt CO2 /PJ]
Gasoline Jet kerosene Other kerosene Diesel oil Fuel oil LPG Naphtha Bitumen Lubricants Petroleum coke Solvent Liquide fuels total
344.637 105.572 404.834 792.580 853.637 361.908 950.096 68.908 35.878 6.801 4.019 3928.869
0.0730 0.0730 0.0730 0.0730 0.0770 0.0660 0.0730 0.0770 0.0730 0.1030 0.0730 –
25.147 7.703 29.539 57.832 65.730 23.886 69.325 5.306 2.618 0.701 0.293 288.081
– – 0.565 – 1.129 1.892 39.646 5.306 1.309 0.526 0.235 50.607
25.147 7.703 28.974 57.832 64.601 21.994 29.679 0 1.309 0.175 0.059 237.473
Anthracite Bituminous coal Solide fuel total
129.541 1667.028 1796.569
0.1030 0.1030 –
13.347 171.759 185.107
– 1.505 1.505
13.347 170.254 183.601
792.282
0.0560
44.447
Natural gas Total fossil fuels
Consumption
6517.720
1 PJ = 1015 J = 0.023885 Mtoe; a
–
Carbon content [Mt CO2 ]
Carbon stored [Mt CO2 ]
CO2 emissions [Mt CO2 ]
517.634 1 Mt = 106 t.
1 Mtoe = 41.86728 PJ; Contains carbon storage of 0.024 Mt CO2 for waxes and paraffins.
– 52.137a
44.447 465.497
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The carbon storages assessed with the NEAT model are by 7.2 Mt CO2 for 1999 and 9.3 Mt CO2 for 2000 higher than those assessed according to the IPCC-RA by using the corrected non-energy use statistics. In sum, Korea emitted 426.7 Mt CO2 against 434 Mt CO2 (the IPCC-RA) for 1999 and 456.2 Mt CO2 against 465.5 Mt CO2 for 2000 from the use of fossil fuels. However, the carbon storage assessed with the NEAT model is by 13.8 Mt CO2 for 1999 and by 12.7 Mt CO2 for 2000 lower than those assessed according to the IPCC-RA by using the uncorrected (official) non-energy use statistics. The current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate the CO2 emissions by 13.8 Mt CO2 for 1999 and by 12.7 Mt CO2 for 2000. The underestimation of the CO2 emissions in Korea is the result of the double counting of the external backflows and the consideration of the internal backflows as non-energy use. The IEA seems to use similar non-energy statistics to estimate the carbon storage, as the estimates are almost as big as the ones calculates by using the uncorrected (official) non-energy use statistics as shown in Table 5.
7. Conclusions This paper has estimated the carbon storage originating from the non-energy use by applying both the IPCC-RA and the NEAT model as to assess carbon release from the use of fossil fuels for the years 1999 and 2000 in Korea. The “official” carbon storage 71.0 Mt (million tons) for 1999 and 74.2 Mt for 2000 calculated according to the IPCC-RA by using the uncorrected non-energy use statistics were by 13.8 and 12.7 Mt smaller than those assessed with the NEAT model with 57.2 and 61.4 Mt, respectively. Thus, the current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate the carbon release. This is because the gross naphtha deliveries are considered as feedstock consumption. The estimation after correction of the non-energy use statistics has shown, however, that the carbon storage calculated according to the IPCC-RA by using the corrected non-energy use statistics were lower than those calculated by using the NEAT model. On the one hand, this is because the IPCC storage fraction 0.75 for naphtha seems to be too low for the Korean petrochemical production structure. The fact that the carbon storage with 50.0 Mt for 1999 and 52.1 Mt for 2000 assessed according to the IPCC-RA were by 7.2 and 7.0 Mt lower than those assessed by the NEAT model (without the international trade) with 57.3 and 59.1 Mt, respectively and that naphtha accounts for about 84% of the non-energy use excluding bitumen indicates that the storage fraction for naphtha should be raised from 0.75 (IPCC default fraction) to 0.88. Furthermore, this study has shown that the current Korean non-energy use statistics is not adequate for carbon accounting. First, it does not list all fossil fuels used in the petrochemical sector as feedstock. Fuel oil, LPG, kerosene and coal tars are also used as feedstock in Korea. As shown in Tables 6 and 7, these fuels used as feedstock were responsible for the carbon storage in the amount of 5.0 Mt in 1999 and 5.1 Mt in 2000. Second, the consumption of naphtha, the major feedstock, is double counted in the Korean energy balances in the amount of the backflows from the petrochemical sector (mostly from BTX plants) to refineries. These external backflows amounted to 7.3 Mt or about 22.1% of
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the gross naphtha deliveries or about 3.7% of Korea’s primary energy consumption in 2000. And the Korean energy balances do not distinguish the net naphtha consumption between feedstock use and fuel use. Only 59.4% of the gross naphtha deliveries or 76.2% of the net naphtha consumption resulted in the extraction of high value petrochemicals in 2000. The balance 23.8%, the use of fuel by-products like methane, fuel oil and mixed C4 produced in the naphtha cracking process, was used as process fuel within the steam cracker or sold in forms of LPG on the market. This external and internal naphtha backflows have to be subtracted from the gross deliveries of naphtha from the refineries to the petrochemical sector. Indeed, this study has discovered a big discrepancy between the carbon storages assessed according to the IPCC-RA and by the NEAT model. A detailed analysis on the Korean naphtha flow has shown that among other things the naphtha backflows to refineries have been double counted in the Korean energy balance, which forms the basis of the IPCC-RA calculation. This caused to a thorough study of the Korean energy balance and led to a 4-year project to revise the energy balances back to 1990. In conclusion, this paper has shown that a material flow analysis like the NEAT model can provide a better basis for estimation of CO2 emissions of the non-energy use and with it that of the fossil fuel use than the current IPCC guidelines. The NEAT model can consider the international trade with ODU petrochemicals and estimate the storage fraction for naphtha. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. This paper has made plain once more the importance of accurate energy statistics, in this case, non-energy use statistics. The energy statistics should be adequate for carbon accounting.
Acknowledgements The author is grateful for the expert discussions on an earlier draft of this paper, especially by Martin Patel and Maarten Neelis (Utrecht University, the Netherlands). Furthermore, the author expresses thanks to numerous experts from the Korean petrochemical industry, the Korea Petrochemical Industry Association and the Korea National Oil Corporation for their valuable information. This work was supported by Inha University Research Grant (INHA2003).
References Chemical Research Institute. Chemical Annual. Seoul, Korea, various years (in Korean). IPCC/IEA/OECD/UNEP, 1997. Revised 1996 IPCC guidelines for national Greenhouse gas inventories, vol. 1–3. UK: IPCC Working Group I Technical Support Unit, Hadley Centre, Bracknell. Korea National Oil Corporation (KNOC). Korea Oil Statistics. Seoul, Korea, various years (in Korean). Korea Petrochemical Industry Association (KPIA). Petrochemical Annual. Seoul, Korea, various years (in Korean). Marland G, Rotty RM. Carbon dioxide emissions from fossil fuels: a procedure for estimation and results for 1950–1982. Tellus 1984;36B(4):232–61. Neelis ML, Patel M, Gielen DJ, Blok K. Modelling non-energy use CO2 emissions and carbon storage with the non-energy use emission accounting tables (NEAT). Resour Conserv Recycl 2005;45:226–50.
Fossil fuel use and CO2 emissions in Korea: NEAT approach Hi-chun Park ∗ Department of Economics, Inha University, 253 Yonghyun-Dong, Nam-Ku, Incheon 402-751, Republic of Korea Available online 15 August 2005
Abstract Carbon accounting is a key issue in the discussions on global warming/CO2 mitigation. This paper applies both the intergovernmental panel on climate change-reference approach (IPCC-RA) and the non-energy use emission accounting tables (NEAT) model, a material flow analysis, to estimate the carbon storage originating from the non-energy use as to assess the carbon release from the use of fossil fuels in Korea for the years 1999 and 2000. The current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate CO2 emissions. This is because the gross naphtha deliveries are currently considered as feedstock use. The estimation after correction of the non-energy use statistics shows, however, that the carbon storage calculated according to the IPCC-RA are lower than those calculated using the NEAT model. This is because the IPCC default storage fraction for naphtha used in Korea seems to be too low for the Korean petrochemical production structure. A by-product of this study is the identification of a double counting of naphtha consumption in the amount of the backflows to refineries in the Korean energy balance which led to a four-year project to revise the energy balances back to 1990. This paper shows that a material flow analysis like the NEAT model can provide a better basis for estimation of CO2 emissions of the non-energy use and with it that of the fossil fuel use than the current IPCC-RA. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. © 2005 Elsevier B.V. All rights reserved. Keywords: Non-energy use; Carbon accounting; CO2 emissions; Korean petrochemical industry; Material flow analysis
∗
Tel.: +82 32 860 7781. E-mail address: [email protected].
0921-3449/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.resconrec.2005.05.006
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1. Introduction The combustion of fossil fuels results in carbon release (CO2 emissions), which is the major source of anthropogenic CO2 emissions according to current knowledge. Fossil fuels are also used for non-energy use purposed, either directly (e.g. the use of some refinery products like lubricants) or as feedstock for the manufacture of synthetic organic products. Some of these products (e.g. plastics) only lead to Greenhouse gas (GHG) emissions during incineration of post-consumer waste or do not lead to GHG emissions at all (e.g. bitumen or landfilled plastics). We refer to these chemicals as chemicals that are not oxidized during use (NODU). In contrast, the carbon embedded in another group of products, such as detergents, some solvents and part of lubricants is released to the atmosphere partially or fully during the use phase of the chemicals. We refer to these chemicals as products that are oxidized during use (ODU). ODU products are assumed to lead to CO2 emissions directly within the inventory year. As all commodities, ODU products are traded and hence the products used in a given country are typically partly produced domestically and partly imported. Emission inventories should correct for this international trade in order to calculate the correct GHG emissions. NODU products only lead to GHG emissions during the incineration of post consumer waste. As such carbon storage in NODU products only contributes to global warming/climate change if the products are incinerated. A country’s CO2 emissions from the use of fossil fuels can be estimated as the difference between the carbon content of the total fuel use and the carbon storage. As the total fossil fuel use can be calculated relative easily from the national energy balances1 , the main problem rests on the estimation of the carbon storage from the non-energy use. The non-energy use, predominantly feedstock consumption, amounted to about 6.5% of the total primary energy supply (TPES) for 2000 in the European Union. These shares are higher in the Netherlands and Korea with about 13.5 and 14.1%, respectively (Neelis et al., 2005). Thus, it is particularly important to estimate exactly the carbon storage for countries with a large share of non-energy use compared to the total national fossil fuel use. These estimates can have importance in discussions on CO2 emissions. For instance, if carbon taxes are introduced, underestimation of the carbon storage will adversely affect the petrochemical industry. On the other side, overestimation of the carbon storage will mean wrong incentives for this industry. This paper calculates the carbon storage from the non-energy use to assess the CO2 emissions from the use of fossil fuels in Korea for the years 1999 and 2000. First, accounting methods for carbon storage are discussed in Section 2. Section 3 gives a brief overview of the Korean petrochemical industry. Sections 4 and 5 estimate the carbon storage from the non-energy use in Korea by using the IPCC-RA default storage fractions and the NEAT model, respectively. Section 6 compares the total CO2 emissions estimated by using various models. At the end some conclusions will be drawn.
1
Required is a sound energy balance for fossil fuel consumption.
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2. Accounting approaches for carbon storage Well known are the reference approach (RA) and sectoral or standard approach (SA) according to the IPCC guidelines (IPCC/IEA/OECD/UNEP, 1997). The IPCC-RA calculates the CO2 emissions by deducting the carbon storage from the non-energy use from a country’s total fossil fuel use. The IPCC-SA adds up emissions for individual activities (or source categories), such as energy use, industrial processes, solvent use and waste. In contrast, the NEAT model traces carbon storage in petrochemical processes and flows within a country’s organic/petrochemical complex based on material flow analysis. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. The IPCC-SA will not be elaborated further, as only the IPCC-RA and the NEAT model will be compared with each other. 2.1. The IPCC reference approach The IPCC guidelines indicate that storage of fossil carbon in synthetic organic materials and products should be taken into account. They make a distinction between carbon storage in products over long periods and short-term release of carbon.2 Only long-term storage originating from the non-energy use should be subtracted from annual national CO2 emissions due to the use of fossil fuels. Hence, emissions from short-life (less than 20 years in general) materials and incineration of long-life materials do not belong to the carbon storage. They are considered as CO2 emissions. According to the IPCC-RA, the carbon storage can be calculated by multiplying the non-energy use of fuels QNEU (given as lower heating value in GJ) by the respective storage fraction P and the emission factor EF (kg CO2 /GJ) as follows: storage EIPCC = {QNEU Pi EFi } (1) i
with i indicating the type of fuel. The IPCC guidelines (IPCC/IEA/OECD/UNEP, 1997) provide default values for Pi as given in Table 6. Alternatively, the carbon release can be calculated as the difference between the total emissions and the carbon storage of fuels with the following formula: release EIPCC = {QNEU,i (1 − Pi )EFi } (2) i
Limitations of the calculation under the IPCC reference approach can be summarized as follows: • The default carbon storage fractions P that are proposed for the IPCC-RA are based on work done by Marland and Rotty for 1950–1982 in the US (Marland and Rotty, 1984). These might not hold for other countries in consideration. For instance, the storage 2 This study distinguishes between ODU and NODU products instead of short-life and long-life products as to ensure a clear allocation of product related emissions to the IPCC source categories. For a more detailed discussion, reference is made to Neelis et al., 2005.
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fraction 0.75 for naphtha is rather low for countries like Korea, which has a higher production share of NODU petrochemicals. On top of this, Marland and Rotty’s storage fractions represent the share of the non-energy use of a fuel, which remains unoxidised for long periods of time. The use of such fractions in the IPCC-RA leads to CO2 emission estimation comprising fuel combustion, waste incineration and (autonomous) product oxidation. In contrast, the purpose of the IPCC-RA is generally regarded as a validation tool for CO2 emissions from fuel combustion only (Neelis et al., 2005). • Default values of storage fractions P and emission factors EF are not given for all types of fuels. • The IPCC-RA does not consider the trade with petrochemicals. This can have consequences to the results of countries with large net imports or net exports. • The IPCC-RA is based on non-energy use data from the energy statistics. While these data are well-suited for energy accounting, they are less suited for carbon accounting. To overcome some of these limitations, a material flow analysis like the NEAT model can be applied. 2.2. The NEAT model version 2.0 The non-energy use emission accounting tables (NEAT) model developed by the NEU–CO2 network estimates carbon storage based on a material flow analysis of the petrochemical sector. The model contains the conversion routes from 22 basic chemicals to 55 intermediate and final products (Table 4). The total consumption of final products and the consumption of intermediates and basic chemicals for other derivatives is divided into ODU and NODU applications. For the consumption of intermediates for other derivatives, the fraction of ODU versus NODU has been based on consumption patterns for intermediates found in literature. The part of the non-energy use, which is stored (i.e. not emitted) in the country of study is calculated as the sum of two elements (see also Neelis et al., 2005): 1. the consumption of NODU products in the country of study, and 2. the net export of all basic chemicals3 , intermediates and final products included in the NEAT model. All flows are converted to CO2 equivalents and carbon yields in the various conversion steps are set to 100%. A sensitivity analysis is included in the NEAT model for the division between ODU and NODU applications.
3. The Korean petrochemical industry The Korean petrochemical industry grew rapidly in the period 1988–2000. Table 1 shows that the production capacities for ethylene, propylene, benzene, xylene, styrene monomer, high density polyethylene (HDPE), terephthalic acid (TPA) increased by 6–13 times. For 3 Excluding the non-energy use refinery and coke oven products for which the trade is already accounted for in the energy statistics.
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Table 1 Capacity trend of Korean petrochemical plants for 1988–2000 (in kilotons)
Ethylene Propylene Benzene Toluene Xylene P-xylene Styrene monomer HDPE Polypropylene Polystyrene PVC TPA Carbon black
1988
1990
1992
1996
2000
505 268 309 292 338 160 230 280 660 373 530 500 205
1155 625 558 418 758 560 675 743 805 787 610 1160 250
3255 1895 1241 751 1527 560 1135 1173 1310 925 710 1210 340
4340 2602 1633 1195 2286 1400 1645 1503 2105 1036 1045 3110 530
5150 3476 2587 1910 2288 3280 2255 1792 2518 1112 1240 4470 530
Source: Korea Petrochemical Industry Association, Petrochemical Annual 2001, Seoul.
instance, the number of naphtha crackers rose from two in 1988 to seven in 2000. As a result, the naphtha cracking capacities increased from 0.505 Mt (million tons) to 5.150 Mt. In comparison, only the USA (27.014 Mt), Japan (7.410 Mt) and Germany (5.215 Mt) had higher cracking capacities than Korea in 2000. The Korean petrochemical industry uses almost exclusively naphtha as feedstock for its high severity naphtha cracker in which about 31% of the production is ultimate ethylene yield. Korea’s gross exports of petrochemicals amounted to US$ 9.4 billion in 2000. Among the most important exported petrochemicals were polypropylene, HDPE, low density polyethylene (LDPE), acrylonitrile butadiene styrene (ABS), styrene monomer (SM), polystyrene, TPA, etc. Gross imports of petrochemicals had a value of US$ 4.5 billion in 2000. Major importing chemicals were p-xylene, ethylene glycol, caprolactam, xylene, etc., as shown in Table 2. Korea is hence a net exporter of petrochemicals in the amount of US$ 4.9 billion. Table 2 Korean trade with major petrochemicals in 2000 Exports
Polypropylene ABS HDPE Styrene momomer Polystyrene LDPE TPA P-xylene Toluene PVC
Imports
Million $
Mt
808 712 683 646 600 573 563 421 323 281
1.328 0.592 1.022 0.894 0.602 0.829 1.253 0.987 1.011 0.410
Ethylene glycol P-xylene Caprolactam Xylene Ethylenedichloride Methanol Styrene momomer – – –
Source: Korea Petrochemical Industry Association, Petrochemical Annual 2001, Seoul.
Million $
Mt
400 385 343 263 185 181 165 – – –
0.710 0.845 0.244 0.784 0.512 1.091 0.218 – – –
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The Korean petrochemical industry produced in 2000 petrochemicals in the amount of US$ 20.455 billion which corresponded to 45.8 and 12% of the production in the chemical industry and in the manufacturing industry, respectively. However, it was relatively less value added intensive and less manpower intensive than other sectors of the manufacturing industry. The petrochemical industry’s contribution to the manufacturing industry’s value added and employment were hence only 3.1 and 0.9%, respectively.
4. Carbon storage with the IPCC-RA default storage fractions To estimate the carbon storage according to the IPCC-RA, it is necessary to know the amounts of fossil fuels by types used as feedstock for the manufacture of petrochemicals (non-energy use of fossil fuels). The Korean energy balances list only naphtha, asphalt/bitumen, lubricants, waxes and paraffins, petroleum coke and solvent as non-energy use, while, in reality, the Korean petrochemical industry uses also LPG, kerosene, fuel oil and coal as feedstock. There is hence need to improve the Korean non-energy use statistics. Those feedstocks, which are not listed in the Korean energy balances should be collected and reported. This would ultimately lead to more accurate results for the IPCC-RA. According to investigations by the author LPG, kerosene, fuel oil and coal are used for the following purposes: LPG, mostly butane, is required to produce synthetic gas, which is in turn needed by some petrochemical firms for the production of maleic anhydride (MA). Kerosene is converted to normal paraffin for the production of alkyl benzene which is needed in turn for the detergent production. Propylene is produced as by-product (4–5%) in the residual fluidized catalytic cracking (RFCC), which converts fuel oil to gasoline. And pitch, naphthalene, creosote oil and coal tars are produced from coal. For instance, coal tars are converted to carbon black. Information on LPG was collected from the Korea National Oil Corporation. In the case of coal tars, information on their consumption and international trade was gathered from the sole producer of carbon black in Korea. And information on kerosene and fuel oil were provided from concerned firms. All this data is listed in Table 6 for 2000.4 In the case of naphtha, by far the largest feedstock in the petrochemical industry, the Korean energy balances give only information in gross terms. According to it, Korea used naphtha in the amount of 1219.6 PJ (29.1 Mtoe, at 41.9 PJ/Mt) which is equivalent to 15.1% of the total energy consumption of 8075.7 PJ (192.9 Mtoe) in primary energy terms (TPES). However, this value includes the backflows from steam crackers to refineries (external naphtha backflows) and the fuel by-products used as process fuel in the petrochemical sector (internal naphtha backflows). This paper estimates the external and internal naphtha backflows by analyzing material balances of naphtha using companies. There were six naphtha steam crackers or naphtha cracking centers (NCC) with aromatics recovery (BTX), four refineries with aromatics recoveries (BTX), one refinery with steam cracking and aromatics recovery (NCC, BTX) and eight other petrochemical companies with a total net naphtha consumption of 25.619 Mt (228.007 Mbbl) in 2000. 4 In order not to overload this paper with large tables the ones for the year 1999 are omitted. These are available on request from the author.
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On the one hand, Korean naphtha steam crackers (NCC, BTX) extract apart from basic chemicals, such as ethylene, propylene, pyrolysis gasoline (PG) and styrene hydrogen, methane, propane, fuel oil and mixed C4 which can be used all or partly as process fuel. They operate BTX plants to extract benzene (ca. 26.6% of the PG input), toluene (ca. 15.9%) and xylene (8.5%) from PG (ca. 20% of the naphtha input). On the other hand, Korean refineries extract in their BTX plants from naphtha apart from benzene, toluene, xylene and para-xylene LPG, heavy aromatics, C5 and C6 naphtha, etc., which can be also used as fuel. Thus, it is necessary to make a correction for that part of naphtha, which is used as fuel internally (process fuel) as well as externally (by-products returned to refineries for the production of gasoline, for instance).5 Korean petrochemical companies report quarterly their material balances to the government to get reimbursed the “petroleum tax” paid on naphtha used as feedstock and process fuel. In Korea apart from a 5% customs duty a petroleum tax of Won 14 per liter (Won 2226 or US$ 1.78 per barrel) is levied on imports of crude oil and petroleum products. This tax is used to finance strategic petroleum stockpiling and development of new and renewable energy. Table 3 shows that domestically produced and imported naphtha in the amount of 16.535 Mt were delivered to six steam crackers (NCC, BTX) in 2000. The steam cracking resulted in the extraction of 11.997 Mt high value petrochemicals (72.6%) and 4.538 Mt by-products (27.4%). From these by-products 3.591 Mt (21.7% of gross naphtha deliveries) were used as process fuel within the steam cracker (internal backflows). And 0.686 Mt (4.2%) were sold in forms of LPG on the market. As the remaining 0.261 Mt (1.6%) was sent back to refineries, the net naphtha consumption by six steam crackers was 16.274 Mt (98.4%). Refineries operate BTX plants to extract benzene, toluene and xylene from naphtha. The extraction of these petrochemicals amounted to 3.524 Mt or 38.2% of naphtha input of 9.223 Mt in 2000. And 0.808 Mt by-products (8.8%) were used as process fuel. The remaining by-products of 4.891 Mt were sent back to the refining sector. Table 3 lists one refinery, which also operates two NCC. It extracted 3.393 Mt petrochemicals. The by-products were partly sent back to the refining sector and partly used as process fuel within the steam cracker. As the entire petrochemical sector returned by-products of 7.253 Mt (22.1%) out of the gross naphtha deliveries 32.871 Mt to the refineries for the production of gasoline, only the balance 25.619 Mt should be considered as the net naphtha consumption (Table 3). Furthermore, the petrochemical sector used 5.421 Mt by-products (16.5%) as process fuel and sold 0.686 Mt by-products (2.1%) in forms of LPG on the market. The gross naphtha consumption of the Korean petrochemical industry with 1377.3 PJ is much bigger than that of the Korean energy balance with 1219.7 PJ. As we are unable to revise the Korean energy balance, we will use the official gross naphtha consumption figure but consider only 59.4% of the gross naphtha consumption given in the Korean energy balance as non-energy use or feedstock. A by-product of this study is the identification of some inconsistencies in the concept of the Korean energy balance, which led to a 4-year project to revise the energy balances back 5 Energy balances in some countries consider the internal naphtha backflows as non-energy use. A detailed discussion on steam cracking operation, reference is made to Section 4 in Neelis et al. (2005).
302
Gross naphtha input Backflows to refineries (in percentage of gross input) Net naphtha consumption (in % of gross input) Feedstock use (in % of gross input) Fuel use & losses (in % of gross input) LPG sales on the market (in % of gross input)
NCC, BTX (6)
Refineries BTX (4)
Refinery with NCC (1)
Others (8)
Total (19)
16.535 0.261 (1.6) 16.274 (98.4) 11.997 (72.6) 3.591 (21.7) 0.686 (4.2)
9.223 4.891 (53) 4.332 (47) 3.524 (38.2) 0.808 (8.8)
6.330 2.097 (33.1) 4.233 (66.9) 3.393 (53.6) 0.839 (13.3)
0.783 0.003 (0.4) 0.780 (99.6) 0.597 (76.2) 0.183 (23.4)
32.871 7.253 (22.1) 25.619 (77.9) 19.511 (59.4) 5.421 (16.5) 0.686 (2.1)
Source: quarterly reports (including material balances) of naphtha consuming petrochemical companies.
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Table 3 Korean naphtha flow in 2000, a survey result in Mt
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to 1990. This study has discovered a big discrepancy between the carbon storages assessed according to IPCC-RA and by the NEAT model. A detailed analysis on the Korean naphtha flow has shown that among other things the naphtha backflows to refineries have been double counted in the Korean energy balance, which forms the basis of the IPCC-RA calculation. In fact, the double counting of naphtha consumption stems from a misconception in the current Korean energy balance framework, which does not have any transformation balance for the petroleum sector. Gross deliveries of petroleum products by the domestic refineries are reported as ‘petroleum products’ of the row ‘imports’ in the total primary energy supply (TPES) balance of the Korean energy balance. Crude oil imports do not appear in the energy balance. The TPES balance which has also the function of petroleum transformation in the current energy balance cannot consider any flows between the petroleum sector and the petrochemical sector. A preliminary revision of the Korean energy balance for 2000 reveals that the TPES of the current energy balance is overestimated by 3% (5.565 Mtoe = 233 PJ) from 187.3 Mtoe (7842.7 PJ, revised) to 192.9 Mtoe (8075.7 PJ). This overestimation is mostly due to the double counting of the naphtha consumption in the amount of the external naphtha backflows of 5.390 Mtoe (225.7 PJ).
5. Carbon storage with the NEAT model 5.1. Data To run this model, it is essential to have production and trade data of basic chemicals, intermediates and products as listed in Table 4. The Korea Petrochemical Industry Association publishes annually data on productions for benzene, butadiene, other C4, carbon black, ethylene, propylene, toluene, xylenes (total, o-xylene, p-xylene), acetic acid, acetone, acrylonitrile, butanol, caprolactam, DMT, ethanol, ethylenedichloride, ethylene glycol, octanol, phenol, phthalic anhydride, propylene oxide, styrene, TPA, TDI, VCM, ABS, BR, polyethylene, polypropylene, polystyrene, polyurethane, PVC and SBR (KPIA, 2002). Those for bitumen, petroleum coke and waxes and paraffins are provided by the Korea National Oil Corporation. Data on methanol, naphthalene, m-xylene, acrylic acid, adipic acid, aniline, bisphenol A, cumene, ethylene oxide, formaldehyde, MTBE, EPDM, epoxy resin, phenolic resin, polycarbonate, polyvinylacetate, SAN and unsaturated polyester are taken from the publication of the Chemical Research Institute, a private consulting firm (Chemical Research Institute, 2001, 2003). Data on acetylene, ammonia, lubricants, pitch, creosote oil, other tar products, cyclohexanone, ethylbenzene, i-propanol, melaminformaldehyde resin, PET, urea formaldehyde resin and polyacetals were gathered directly from petrochemical producers or their associations. Trade data are gathered partly from the same sources as production data and partly from the Korea trade statistical database of the Korea international trade association (KITA, http://db.kita.net). One important task of a material flow analysis, such as the NEAT model is the treatment of the use of intermediates in the category “others”. This category includes all types of applications, which have not been elaborated (in some case the total application of products of minor importance “total”). In NEAT, the total assigned to the category “others” is allocated
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Table 4 Korean petrochemical production and trade, 2000 Production [Mt/yr]
Imports [Mt/yr]
Exports [Mt/yr]
Basic chemicals Acetylene Ammonia Benzene Bitumen Butadiene Other C4 Carbon black CO source Ethylene Lubricants Methanol Petroleum coke Pitch Creosote oil Naphthalene Other tar products Propylene Toluene Waxes, paraffins Xylenes (o-, m-, p-, mixed xylene) o-xylene m-xylene p-xylene
0.000 0.448 2.806 2.194 0.730 0.754 0.456 0.400 5.537 0.908 0.000 0.322 0.200 0.080 0.045 0.420 3.602 1.472 0.010 3.549 0.376 0.039 3.135
0.000 0.743 0.236 0.004 0.029 0.000 0.009 0.000 0.099 0.011 1.091 0.000 0.019 0.009 0.000 0.769 0.179 0.000 0.022 0.784 0.013 0.002 0.845
0.000 0.000 0.688 0.514 0.177 0.000 0.127 0.000 0.313 0.090 0.010 0.078 0.200 0.000 0.001 0.211 0.383 1.011 0.007 0.453 0.074 0.003 0.987
Intermediates Acetic acid Acetone Acrylic acid Acrylonitrile Adipic acid Aniline Bisphenol A Butanol Caprolactam Cumene Cyclohexane Cyclohexanone Dimethylterephthalate Ethanol Ethylbenzene Ethylenedichloride Ethylene glycol Ethylene oxide Formaldehyde MTBE Octanol Orthophthalates Phenol
0.389 0.083 0.121 0.357 0.055 0.089 0.038 0.078 0.116 0.081 0.161 0.103 0.135 0.032 2.837 0.590 0.832 0.066 0.450 0.791 0.319 0.510 0.130
0.062 0.028 0.050 0.092 0.030 0.018 0.072 0.010 0.244 0.012 0.056 0.155 0.013 0.096 0.000 0.512 0.710 0.000 0.000 0.052 0.092 0.006 0.017
0.072 0.025 0.065 0.074 0.040 0.000 0.000 0.036 0.000 0.020 0.082 0.000 0.055 0.003 0.000 0.015 0.227 0.000 0.000 0.091 0.079 0.238 0.046
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Table 4 (Continued ) Production [Mt/yr]
Imports [Mt/yr]
Exports [Mt/yr]
Phthalic anhydride (PSA) Polyether-polyols i-Propanol Propylene oxide Styrene Terephthalic acid (TPA) TDI Urea Vinylchloride monomer (VCM)
0.371 0.011 0.043 0.154 2.467 4.291 0.104 0.687 1.329
0.007 0.001 0.025 0.022 0.218 0.005 0.000 0.485 0.031
0.139 0.000 0.008 0.000 0.894 1.253 0.072 0.109 0.175
Products ABS BR EPDM Epoxy resin Melamineformaldehyde resin Phenolic resin Polyacetals Polyacrylates Polyacrylonitrile Polyamide 6,66 Polycarbonate Polyethylene (PE) Polyethyleneterephthalate (PET) Polypropylene (PP) Polystyrene (PS) Polyurethane (PUR) Polyvinylacetate Polyvinylchloride (PVC) SAN Saturated polyester SBR Unsaturated polyester/alkyd resin Urea formaldehyde resin (UF)
0.878 0.171 0.046 0.098 0.024 0.084 0.090 0.119 0.000 0.298 0.073 3.220 0.377 2.347 1.041 0.434 0.016 1.187 0.079 3.216 0.266 0.088 0.001
0.005 0.018 0.002 0.016 0.005 0.026 0.006 0.013 0.000 0.029 0.073 0.058 0.004 0.013 0.015 0.078 0.009 0.031 0.003 0.101 0.021 0.002 0.002
0.592 0.100 0.017 0.049 0.001 0.000 0.063 0.100 0.000 0.061 0.042 1.797 0.021 1.328 0.602 0.196 0.011 0.410 0.061 1.178 0.162 0.013 0.000
59.453
8.512
15.944
Total
Sources: Korea Petrochemical Industry Association, Petrochemical Annual, Chemical Research Institute, Chemical Annual, and own estimates.
to ODU versus NODU products by means of information from literature (see Neelis et al., 2005). 5.2. NEAT results The carbon storage calculated with the NEAT model was 57.2 Mt CO2 for 1999 and 61.4 Mt CO2 for 2000 shown in Table 5. However, there are built-in uncertainties in the NEAT results as the storage due to the consumption of NODU products is for 1999, 34.7 Mt
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Table 5 Comparison of CO2 estimates according to various methods Total use of fossil fuels in CO2 [Mt CO2 ] 1999 2000
Carbon storage from non-energy use [Mt CO2 ] 1999 2000
C02 emissions from use of fossil fuels [Mt CO2 ] 1999 2000
IPCC-RA approacha Statistics uncorrected Statistics corrected IEAb
483.929 483.929
517.634 517.634
70.980 50.003
74.175 52.137
412.949 433.926 413.200
443.463 465.501 444.500
NEAT modelc
483.929
517.634
57.195
61.447
426.734
456.191
a b c
Tables 6 and 7. IEA, CO2 emissions from fuel combustion, 2002 edition. Section 5.2.
CO2 with an uncertainty in the range from 32.9 to 39.3 Mt CO2 and for 2000, 36.1 Mt CO2 with an uncertainty in the range from 34.3 to 39.7 Mt CO2 . The storages calculated with the NEAT model are higher than those according to the IPCC-RA, which was 50.0 and 52.1 Mt CO2 , respectively. This would mean that the IPCC default storage fraction 0.75 for naphtha should not be adequate to assess the CO2 emissions in Korea. As 1% of the naphtha consumption in the Korean petrochemical sector in terms of carbon storage is equivalent to 0.505 Mt CO2 for 1999 and 0.529 Mt CO2 for 2000 and as naphtha accounts for 84.7% of the non-energy use in Korea excluding bitumen, the difference (7.249 Mt CO2 for 1999 and 6.996 Mt CO2 for 2000) between the carbon storage assessed by the NEAT model and according to the IPCC-RA will correspond to 14.4% for 1999 and 13.2% for 2000. As a result, the storage fraction for naphtha should be about 0.88 (0.75 + 0.13). In the case of the Netherlands, 0.82 is used as the storage fraction for naphtha.
6. Total CO2 according to the various methods Once the carbon storage (50 Mt for 1999 and 52.1 Mt for 2000 shown in Table 6) from the non-energy use of fossil fuels are calculated, it is straightforward to estimate the CO2 emissions according to the IPCC-RA (434 Mt for 1999 and 465.5 Mt for 2000) by subtracting the carbon stored from the carbon content of the total national fossil fuel use (483.9 Mt for 1999 and 517.6 Mt for 2000) as shown in Table 7. The change (correction) in the Korean non-energy statistics results in an increase of Korea’s CO2 emissions by 21 Mt from 413 to 434 Mt in 1999 and by 22.1 Mt from 443.4 to 465.5 Mt in 2000. This is because the gross naphtha deliveries are considered as feedstock in the current accounting. As official data for CO2 emissions according to the IPCC-RA are missing, those by the International Energy Agency (IEA) will be compared with the ones assessed with the NEAT model as in Table 5. In fact, Korea’s CO2 emissions 413.2 Mt for 1999 and 444.5 Mt for 2000 estimated by IEA indicate that IEA seems to use similar nonenergy use statistics as the Korean authorities. Thus, the estimates by using the uncorrected non-energy use statistics can be considered as “official” CO2 emissions according to the IPCC-RA.
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Table 6 Estimation of cabon storage in products after correction using the IPCC-RA default storage fractions, Korea, 2000 Non-energy use [PJ]
Storage fraction [%]
Emission factor [Mt CO2 /PJ]
Carbon storage [Mt CO2 ]
Naphtha (energy balances)a Naphtha (corrected)b Lubricantsa Petroleum cokea Bitumen/asphalta Solventa Waxes and paraffinsa Coal tars Kerosene Fuel oilc LPG
1219.636 724.464 35.878 6.801 68.908 4.019 0.419 21.382 9.680 18.330 35.830
75 75 50 75 100 80 80 75 80 80 80
0.0730 0.0730 0.0730 0.1030 0.0770 0.0730 0.0730 0.0939 0.0730 0.0770 0.0660
66.775 39.646 1.309 0.526 5.306 0.235 0.024 1.505 0.565 1.129 1.892
Total (energy balances)
1335.660
–
–
74.175
925.711
–
–
52.137
Total (Corrected) a
Listed in the Korean energy balances. b Backflows to refineries of 265.539 PJ (double counted) and internal backflows of 225.633 PJ (used as process fuel) are excluded. c Amount of the propylene production in residual fluidized catalytic cracking RFCC.
Table 7 Total national fossil fuel use and CO2 emissions in Korea, 2000 Energy carriers
[PJ]
Carbon emissions factor [Mt CO2 /PJ]
Gasoline Jet kerosene Other kerosene Diesel oil Fuel oil LPG Naphtha Bitumen Lubricants Petroleum coke Solvent Liquide fuels total
344.637 105.572 404.834 792.580 853.637 361.908 950.096 68.908 35.878 6.801 4.019 3928.869
0.0730 0.0730 0.0730 0.0730 0.0770 0.0660 0.0730 0.0770 0.0730 0.1030 0.0730 –
25.147 7.703 29.539 57.832 65.730 23.886 69.325 5.306 2.618 0.701 0.293 288.081
– – 0.565 – 1.129 1.892 39.646 5.306 1.309 0.526 0.235 50.607
25.147 7.703 28.974 57.832 64.601 21.994 29.679 0 1.309 0.175 0.059 237.473
Anthracite Bituminous coal Solide fuel total
129.541 1667.028 1796.569
0.1030 0.1030 –
13.347 171.759 185.107
– 1.505 1.505
13.347 170.254 183.601
792.282
0.0560
44.447
Natural gas Total fossil fuels
Consumption
6517.720
1 PJ = 1015 J = 0.023885 Mtoe; a
–
Carbon content [Mt CO2 ]
Carbon stored [Mt CO2 ]
CO2 emissions [Mt CO2 ]
517.634 1 Mt = 106 t.
1 Mtoe = 41.86728 PJ; Contains carbon storage of 0.024 Mt CO2 for waxes and paraffins.
– 52.137a
44.447 465.497
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The carbon storages assessed with the NEAT model are by 7.2 Mt CO2 for 1999 and 9.3 Mt CO2 for 2000 higher than those assessed according to the IPCC-RA by using the corrected non-energy use statistics. In sum, Korea emitted 426.7 Mt CO2 against 434 Mt CO2 (the IPCC-RA) for 1999 and 456.2 Mt CO2 against 465.5 Mt CO2 for 2000 from the use of fossil fuels. However, the carbon storage assessed with the NEAT model is by 13.8 Mt CO2 for 1999 and by 12.7 Mt CO2 for 2000 lower than those assessed according to the IPCC-RA by using the uncorrected (official) non-energy use statistics. The current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate the CO2 emissions by 13.8 Mt CO2 for 1999 and by 12.7 Mt CO2 for 2000. The underestimation of the CO2 emissions in Korea is the result of the double counting of the external backflows and the consideration of the internal backflows as non-energy use. The IEA seems to use similar non-energy statistics to estimate the carbon storage, as the estimates are almost as big as the ones calculates by using the uncorrected (official) non-energy use statistics as shown in Table 5.
7. Conclusions This paper has estimated the carbon storage originating from the non-energy use by applying both the IPCC-RA and the NEAT model as to assess carbon release from the use of fossil fuels for the years 1999 and 2000 in Korea. The “official” carbon storage 71.0 Mt (million tons) for 1999 and 74.2 Mt for 2000 calculated according to the IPCC-RA by using the uncorrected non-energy use statistics were by 13.8 and 12.7 Mt smaller than those assessed with the NEAT model with 57.2 and 61.4 Mt, respectively. Thus, the current Korean carbon accounting seems to overestimate the carbon storage and to concomitantly underestimate the carbon release. This is because the gross naphtha deliveries are considered as feedstock consumption. The estimation after correction of the non-energy use statistics has shown, however, that the carbon storage calculated according to the IPCC-RA by using the corrected non-energy use statistics were lower than those calculated by using the NEAT model. On the one hand, this is because the IPCC storage fraction 0.75 for naphtha seems to be too low for the Korean petrochemical production structure. The fact that the carbon storage with 50.0 Mt for 1999 and 52.1 Mt for 2000 assessed according to the IPCC-RA were by 7.2 and 7.0 Mt lower than those assessed by the NEAT model (without the international trade) with 57.3 and 59.1 Mt, respectively and that naphtha accounts for about 84% of the non-energy use excluding bitumen indicates that the storage fraction for naphtha should be raised from 0.75 (IPCC default fraction) to 0.88. Furthermore, this study has shown that the current Korean non-energy use statistics is not adequate for carbon accounting. First, it does not list all fossil fuels used in the petrochemical sector as feedstock. Fuel oil, LPG, kerosene and coal tars are also used as feedstock in Korea. As shown in Tables 6 and 7, these fuels used as feedstock were responsible for the carbon storage in the amount of 5.0 Mt in 1999 and 5.1 Mt in 2000. Second, the consumption of naphtha, the major feedstock, is double counted in the Korean energy balances in the amount of the backflows from the petrochemical sector (mostly from BTX plants) to refineries. These external backflows amounted to 7.3 Mt or about 22.1% of
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the gross naphtha deliveries or about 3.7% of Korea’s primary energy consumption in 2000. And the Korean energy balances do not distinguish the net naphtha consumption between feedstock use and fuel use. Only 59.4% of the gross naphtha deliveries or 76.2% of the net naphtha consumption resulted in the extraction of high value petrochemicals in 2000. The balance 23.8%, the use of fuel by-products like methane, fuel oil and mixed C4 produced in the naphtha cracking process, was used as process fuel within the steam cracker or sold in forms of LPG on the market. This external and internal naphtha backflows have to be subtracted from the gross deliveries of naphtha from the refineries to the petrochemical sector. Indeed, this study has discovered a big discrepancy between the carbon storages assessed according to the IPCC-RA and by the NEAT model. A detailed analysis on the Korean naphtha flow has shown that among other things the naphtha backflows to refineries have been double counted in the Korean energy balance, which forms the basis of the IPCC-RA calculation. This caused to a thorough study of the Korean energy balance and led to a 4-year project to revise the energy balances back to 1990. In conclusion, this paper has shown that a material flow analysis like the NEAT model can provide a better basis for estimation of CO2 emissions of the non-energy use and with it that of the fossil fuel use than the current IPCC guidelines. The NEAT model can consider the international trade with ODU petrochemicals and estimate the storage fraction for naphtha. The NEAT model can be used as an independent emission calculation tool to verify the IPCC-RA and IPCC-SA as well as to replace them. This paper has made plain once more the importance of accurate energy statistics, in this case, non-energy use statistics. The energy statistics should be adequate for carbon accounting.
Acknowledgements The author is grateful for the expert discussions on an earlier draft of this paper, especially by Martin Patel and Maarten Neelis (Utrecht University, the Netherlands). Furthermore, the author expresses thanks to numerous experts from the Korean petrochemical industry, the Korea Petrochemical Industry Association and the Korea National Oil Corporation for their valuable information. This work was supported by Inha University Research Grant (INHA2003).
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