Carbon Compounds Emissions by Bottom-up Process

Results of the e&e OSCIP Studies:

Evaluation of Carbon Compounds Emissions by the "Bottom-Up" by Coefficients Process

Carlos Feu Alvim feu@ecen.com

Frida Eidelman, Olga Mafra

Omar Campos Ferreira e Rafael Macêdo

This study is part of data survey for the Carbon Balance revision that was the object of the Partnership Contract 13.0020.00/2005 signed by the Economy and Energy – e&e – OSCIP Organization and the Ministry of Science and Technology – MCT. Its content is specifically related to Goal 2 – Estimate of Greenhouse Effect Gases in the Use and Transformation of Energy from 1970 to 2004 by the Bottom-Up by Coefficients Process.

2. Antecedents

For the Initial Brazilian Declaration to the United Nations Framework Convention on Climate Change (MCT, November 2004), the General Coordination of Global Climate Change of the Ministry of Science and Technology – CGMGC/MCT, has consolidated the inventory of emissions of greenhouse effect (GHE) gases The inventory data were supplied by e&e^{^[1]} in the form of emission/energy coefficients that permit to calculate the emission of the different gases in mass of each one of them using data from the National Energy Balance BEN/MME. The values were calculated using as reference the COPPE report consolidated by CGMGC/MCT for the period of the mentioned Initial Declaration (1990 / 1994) and then extended to 1999. Based on these values – within the Agreement (No 01.0065.00-2003) that aimed at calculating the carbon balance in the Brazilian Energy Matrix - e&e has compared these data with those obtained by using the Top-Down Extended – TDE, methodology published in the No 58 issue of the e&e periodical.

The Top-Down methodology, recommended by IPCC (Intergovernmental Panel on Climate Change) in the case of energy sources emissions, calculates the carbon mass contained in the fuels that enter (production + imports) and leave (exports) the economic system of a country. It makes a first evaluation of the carbon mass (converted toCO₂) that is incorporated to the world atmosphere due to different human activities. The non oxidized carbon amounts and those retained in non energy uses are subtracted from this total amount. The TDE methodology extends this approximation to the transformation and consumption phases so that one has for each sector the amount of carbon that “enters” this sector in the form of energy sources according to the usual accounting of the of the national energy balances.

In the Bottom-Up evaluation applied to energy activities one calculates emissions by type of GHE gases by energy source and by type of use in each Sector or “Account” of BEN. In the previous agreement (№01.0065.00/2003) it has been found that the carbon mass contained in CO₂, CO, CH₄ and NMVOCs and then emitted were incoherent as compared with the TDE calculations. Part of this discrepancy is due to the fact that the mass of CO₂ assumed to have been emitted using the Top – Down method considers that the other gases are converted to CO₂ along time as it happens in nature. By using this same assumption in the Bottom-Up approach there will be a double counting of the carbon contained in the other gases.

In the present study it was used a coherent set of emission coefficients that equals the total carbon mass contained in the emitted gases to the “input” value, taking into account corrections regarding retention, non oxidation and in some cases the emissions of wastes.

These coefficients from 1990 to 1999 were used as a first approximation to estimate emissions from 1970 to 2005. The coefficients used were:

· For the years before 1990 the coefficients used were those corresponding to this year;

· From 1990 to 1999, the coefficients corresponding to each year;

· For the years subsequent to 1999, the coefficients of this year.

By the same reference year criterion the emissions of NO_x and N₂O , that do not contain carbon, were estimated.

3. Methodology

The emitted gases that contain carbon, except NMVOCs, have a well known relationship between carbon mass and total mass, namely:

CO₂ c1 = 12/44

CO c2 =12/28

CH₄ c3 = 12/16

For NMVOCs it was assumed a fraction of carbon mass (c4=0,85) based on the average value of industrial emissions.

If m1, m2, m3 and m4 are the masses of these emitted gases the carbon mass conservation gives:

m1.c1 + m2.c2 + m3.c3 + m4.c4 = MC.(1-fnox-fret)

where MC is the carbon mass of fuel used in the sector, fnox is the non oxidized fraction and fret is the retained fraction.

The fractions of non oxidized fuel adopted in the Initial Declaration are generally those recommended by IPCC, taking into account some Brazilian particularities related in most cases to the use of biomass. In general, they are 1% for liquids and 0.5% for gases. The non oxidized and retained fractions are shown in Table 3.1. The retention fraction was assumed to be 1 (100% of retention) in the cases where it value is not available in previous calculations so that eventual non energy uses in years before and after the Inventory can be detected.[2] It should be noticed that the non oxidized fraction previously referred to is fnox=1-fox.

Table 3.1: Oxidation, Retention and Wastes Factors

	Oxidation Factor	Retention Factor	Wastes Factor
	Energy Consumption or Transformation	Non Energy Consumption	Chracoal and Alcohol Production
PETRÓLEUM	0.99	1
HUMID NATURAL GAS	0.995	0.33
DRY NATURAL GAS	0.995	0.33
STEAM COAL 3100 KCAL/KG	0.98	1
STEAM COAL 3300 KCAL/KG	0.98	1
STEAM COAL 3700 KCAL/KG	0.98	1
STEAM COAL 4200 KCAL/KG	0.98	1
STEAM COAL 4500 KCAL/KG	0.98	1
STEAM COAL 4700 KCAL/KG	0.98	1
STEAM COAL 5200 KCAL/KG	0.98	1
STEAM COAL 5900 KCAL/KG	0.98	1
STEAM COAL 6000 KCAL/KG	0.98	1
STEAM COAL WITH OUT SPECIFICATION	0.98	1
NATIONAL METALURGICO COAL	0.98	1
IMPORTED METALURGIC COAL	0.98	1
OTHER NON RENEW. PRIM. SOURCES	0.99	1
FIREWOOD	0.87 (0.89 in charcoal plants)	1
SUGARCANE LIQUOR	0.99	1
MOLASSES	0.99	1
BAGASSE	0.88	1
BLACK LIQUOR	0.99	1
OTHER RECOVERIES	0.99	1
DIESEL OIL	0.99	1
FUEL OIL	0.99	1
MOTOR GASOLINE	0.99	1
AVIATION GASOLINE	0.99	1
PETROLEUM LIQUIFIED GAS	0.99	1
NAPHTHA	0.99	0.8
ILLUMINATING KEROSENE	0.99	1
AVIATION KEROSENE	0.99	1
COKING PLANT GAS	0.99	1
PIPED GAS RIO DE JANEIRO	0.99	1
PIPED GAS SÃO PAULO	0.99	1
MINERAL COAL COKE	0.99	1
CHRACOAL	0.99	1	0.3
ANHYDROUS ETHYL ALCOHOL	0.99	1	0.71
HYDRATED ETHYL ALCOHOL	0.99	1	0.71
REFINERY GAS	0.99	1
PETROLEUM COKE	0.99	1
OTHER PETROLEUM ENERGY SOURCES	0.99	1
OTHER SECONDARY - TAR	0.99	0.75
ASPHALTS	0.99	1
LUBRICANTS	0.99	0.5
SOLVENTS	0.99	1
OTHER NON ENERG.OF PETROLEUM	0.99	1

The above listed coefficients as well as the gases emission coefficients were adopted for an aggregated item and for its components. So the same oxidation factor was used for the several types of steam coal. These coefficients should be the object of specific studies in the future. In effect it should be expected that in the case of steam coal a larger amount of ashes in coals with lower calorific power would have a less complete burning and therefore would have its oxidation reduced.

The gases emission coefficients supplied by CGMGC/MCT referred to data of the energy balance available at the time of the Inventory when the HCV (high calorific value) concept and the old ton oil equivalent (toe = 10800 Mcal) were still used in the denomination of the present study and in the ancillary calculation programs. The carbon mass emitted was calculated by multiplying the emission coefficients supplied for the energy source and the emitted gas by the energy amount expressed in toe.

The procedure and the modifications adopted are more evident if we take as example the CO emissions (carbon monoxide) in diesel used in highway transport in 2005. The emission factors used for this year were those of the last year when MCT supplied the values (1999).

· The volume of diesel consumed was 30,428 thousand m³ or 25,323 thousand old toe, the CO emission coefficient is 0.0430 t of CO per old toe or 1088 thousand t of CO that contains 466 thousand t of carbon (1088*12/28);

· This same volume of diesel, expressed in new toe is 25,803 thousand toe or 1080 thousand TJ that multiplied by the 20.2 tC/TJ factor is equivalent to a mass of 21,824 thousand t of carbon contained in diesel;

· That is, 466/21,824 = 2.14% of carbon contained in diesel for road transport is emitted as CO.

The emission factor for wastes means that for each carbon atom contained in alcohol, 0.71 atoms of CO₂is produced due to fermentation and residual carbon contained in vinhoto. In a first approximation, it was assumed in the present study that this carbon would appear in the atmosphere as CO₂. This assumption is true in the case of CO₂ due to fermentation but it is less valid for vinhoto in which part of it takes the form of CH₄.

In the case of charcoal plants, pyroligneous liquor and wood tar are produced. Since there are no studies regarding the matter, the emissions from these compounds were considered as those supplied by the CGMGC/MCT and the information regarding the production of residues were not used in the emissions.

The calculation shown in Table 3.2 demonstrates how the emission coefficients as a percent of carbon content were expressed. Since the aim of the study is to reach a carbon balance, the adoption of emission coefficients for each fuel in percent of contained carbon and that takes into account the fraction of oxidized or retained carbon automatically renders the emitted mass equal to that used in the sector (calculated using the TDE methodology).

Table 3.2: Example of Fractioned Coefficients Application to the Calculation of CO Emission from Diesel use in Road Transport in 2005

Calculation	Specification	Quantity	Unit	Observation
a	Natural Units	30429	thousand m³
b	Conversion factor old toe	0.8322	toe ant/m³
c=a*b	Energy	25323	thou. old toe
c	CO emission factor	0.0430	t CO/old toe
d=b*c	CO emissions	1088	thousand t	Gg
e	Conversion factor toe	0.8480	toe/m³
f=a*e	Energy	25804	thousand toe
g	Conversion factor toe in TJ	0.0419	TJ/toe
h	Energy	1080	thousand TJ
i	Carbon mass per energy	20.2	tC/TJ	PCI
j	Carbon mass in fuel	21824	thousand t	Gg
k	Carbon fraction in CO =12/28	0.4286
l=k*d	Carbon mass in CO	466	thousand t	Gg
m=l/j	C mass fraction emitted as CO	2.14%	C in CO/ C in diesel

In order to reach a coherent set of emission coefficients relative to carbon contained in the fuel, the factors initially available (in tons of gas emitted per old toe) were normalized using the original coefficients.

The procedure was to calculate the percent of contained carbon using the bal_eec program. The re-normalization was carried out changing the percent of CO₂. With the objective of checking eventual incoherence and omissions in the emission factors, the coefficients for all years and all fuels of the “accounts” were examined. In some cases the coefficients were not available for all “accounts” even though the use of the fuel was recorded in the corresponding sector. In this case the average values for the sector of the same group (e.g.: industrial) or the values of a similar activity (e.g.: railway and maritime transport) were used.

Table 3.3 shows how re-normalization was carried out. This example is for the same case of the previous table.

Table 3.3 Re-normalization of Factors in % of Carbon for Diesel in the Road Transport Sector

	CO₂	CH₄	CO	NMVOCS	Fnox	Fret	Total	CO₂ Corrected--
ROAD	99.748	0.019	2.138	0.848	1.000	0.000	103.753	95.996
ROAD Re-normalized	95.996	0.019	2.138	0.848	1.000	0.000	100.000

In the example shown, the percent of emitted and retained carbon would be more than 100% ; the correction is applied to the percent of CO₂. The same percent values were used in diesel in the railway and hydro-way sectors.

4. Results of Carbon Emissions and of its Compounds

The bal_ee program, originated from ben_eec, was modified to permit the calculation of emissions from the GHE gases CO₂, CH₄, NMVOCs, CO, NO_x and N₂O besides the calculation of energy, equivalent energy and carbon balances. The description of the program will be provided soon in this periodical. The sum of the contained carbon is the total carbon liberated to the atmosphere.

In Tables 4.1, 4.2, 4.3, 4.4, and 4.5are shown for chosen years between 1970 and 2005, the emissions per fuel of Carbon (total), CO₂, CH₄, CO and NMVOCs respectively.

Table 4.1 Carbon Emissions perFuel, 1970/2005 Period, in Gg/year

	1970	1975	1980	1985	1990	1994	1995	2000	2005
NATURAL GAS	615	460	878	2301	2537	2999	3163	6542	12423
STEAM COAL	617	610	1291	2657	2068	2070	2077	2817	2360
MET. COAL	0	0	0	0	0	277	653	2634	3363
OTHER NON RENEW.	44	39	95	178	287	259	258	679	833
DIESEL OIL	4675	8608	13451	14650	18009	20482	21887	25955	28691
FUEL OIL	6629	11906	15073	8255	9105	9931	10477	10119	6357
GASOLINAE	5834	8827	6940	4777	5863	7274	8699	10432	10681
LPG	974	1436	2169	2926	4054	4364	4621	5590	5076
NAPHTHA	1	205	284	673	830	1031	1020	1359	1218
ILLUM. KEROSENE	403	395	356	223	155	98	82	45	20
AVIATION KEROSENE	513	1008	1343	1456	1550	1653	1929	2524	2063
REFINERY GAS	175	854	884	1301	1410	1670	1595	2143	2828
PETROLEUM COKE	0	0	0	435	445	618	737	3780	4353
OTH.EN. PETROLEUM	38	81	709	461	546	704	881	1804	1768
CITY GAS	99	130	171	219	211	106	90	64	0
ASPHALTS	0	0	0	0	0	0	0	0	0
LUBRICANTS	0	0	0	310	292	268	282	344	358
SOLVENTS	0	0	0	0	0	0	0	0	0
OTH.NON EN.PET.	0	0	0	0	0	0	0	0	0
MIN. COAL COKE	1445	1959	3908	6040	6274	8221	8322	7953	7847
COKE PLANT GAS	170	226	402	692	736	813	821	769	790
OTH.SEC. TAR	30	41	94	119	182	254	243	145	97
NON RENEWABLE	22262	36786	48049	47672	54553	63090	67838	85700	91126
FIREWOOD	-6841	-9095	-9789	-12062	-11333	-9782	-9062	-8591	-10988
SUGARCANE LIQUOR	-68	-63	-1498	-5166	-5009	-4970	-4795	-3728	-5109
MOLASSES	-235	-218	-410	-695	-675	-884	-988	-1109	-1939
OTHERS	-1	-3	-36	-78	-66	-72	-61	-31	-115
BAGASSE	-394	-467	-853	-1471	-1417	-1825	-1807	-1716	-2756
BLACK LIQUOR	-1	-3	-7	-9	-11	-18	-18	-24	-36
OTHER RECOVERIES.	0	0	-29	-69	-55	-53	-43	-7	-80
CHARCOAL	1970	4115	5292	7659	7604	6607	6089	5964	7741
ETHYL ALCOHOL	77	67	1107	3299	4561	5175	5351	4534	5424
RENEWABLE WASTE	181	168	1076	3334	3290	3599	3668	3122	4678
RENEWABLE	-5314	-5499	-5148	-5259	-3113	-2222	-1666	-1587	-3179
TOTAL	16948	31288	42901	42412	51440	60868	66172	84113	87947

Table 4.2: CO₂Emissions per Fuel, 1970/2005 Period in Gg/year

	1970	1975	1980	1985	1990	1994	1995	2000	2005
NATURAL GAS	2254	1686	3216	8428	9291	10982	11581	23945	45431
STEAM COAL	2261	2147	4654	9655	7571	7580	7607	10321	8649
MET. COAL	0	0	0	0	0	1014	2391	9642	12309
OTHER NON RENEW.	160	141	344	642	1037	938	935	2464	3016
DIESEL OIL	16707	30768	48097	52422	64405	73283	78317	92831	102607
FUEL OIL	24241	43485	55108	30078	33274	36294	38298	37000	23206
GASOLINAE	12082	18272	14370	9893	12136	19554	23388	28049	28723
LPG	3570	5264	7948	10722	14854	15992	16934	20483	18598
NAPHTHA	4	596	939	2467	3044	3780	3739	4983	4467
ILLUM. KEROSENE	1477	1445	1303	816	567	359	302	166	74
AVIATION KEROSENE	1871	3680	4904	5313	5657	6033	7040	9212	7531
REFINERY GAS	501	2416	3143	3746	4343	5870	5466	7839	10355
PETROLEUM COKE	0	0	0	1595	1540	2175	2524	13765	15951
OTH.EN. PETROLEUM	138	298	2599	1690	2003	2581	3230	6613	6480
CITY GAS	364	477	628	803	773	389	329	236	0
ASPHALTS	0	0	0	0	0	0	0	0	0
LUBRICANTS	0	0	0	1135	1070	981	1034	1261	1313
SOLVENTS	0	0	0	0	0	0	0	0	0
OTH.NON EN.PET.	0	0	0	0	0	0	0	0	0
MIN. COAL COKE	5279	7155	14276	22065	22918	30033	30403	29054	28656
COKE PLANT GAS	511	764	1390	2471	2608	2877	2931	2785	2890
OTH.SEC. TAR	112	151	346	436	667	928	882	532	354
NON RENEWABLE	71532	118747	163265	164377	187757	221643	237333	301182	320608
FIREWOOD	-43715	-51584	-51947	-58114	-52716	-45425	-42071	-40429	-51529
SUGARCANE LIQUOR	-251	-233	-5494	-18943	-18368	-18222	-17582	-13668	-18734
MOLASSES	-863	-801	-1505	-2548	-2474	-3240	-3623	-4068	-7108
OTHERS	-7	-12	-140	-325	-289	-306	-268	-169	-506
BAGASSE	-1853	-2199

No 61 Em Português

Results of the e&e OSCIP Studies:

Evaluation of Carbon Compounds Emissions by the "Bottom-Up" by Coefficients Process

1. Introduction

2. Antecedents

3. Methodology

4. Results of Carbon Emissions and of its Compounds