Economy & Energy
Year VIII -No 48:
February - March 2005  
ISSN 1518-2932

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Article:

Carbon BALANCE in THE ProduCTION, TransformaTION AND UsE OF EnergY IN BraZil– MetHodologY AND Results Of The "Top-Bottom" PROCESS FROM 1970 TO 2002.

1. Carbon Balance Project.

2. Methodology.

3. Carbon Content in Energy Sources.

    Calculation of the Carbon Content.

    Results for the Contained Carbon.

 

Carlos Feu Alvim (coordinator)

Frida Eidelman

Omar Campos Ferreira

1. Carbon Balance Project

The Carbon Balance Project, executed by the NGO Economy and Energy – publisher of this periodical - aims at supplying a tool for calculating the carbon balance in the production, transformation and use of energy in Brazil and for calculating the carbon content in the emissions of greenhouse effect gases, and the dissemination of the results in electronic form and printed reports

The objective is to detect – through the simultaneous application of the Top-Down and Bottom-Up techniques – the possible omissions in one of the two approaches that could be due to incoherence of the coefficients used or flaws in the emissions calculation. The principle used is that carbon atoms do not disappear in the fuel use process and in each phase of the process the original quantity of carbon (contained mass) must be the same as that emitted or captured by some process.

The present study, carried out under an agreement with the Ministry of Science and Technology (MCT), has concentrated on the methodology and diagnoses of the deviations found. Suggestions regarding the treatment of the problems and the establishment of a coherent balance will be presented at the conclusion of the present report. The necessary corrections will be made afterwards.

The comparisons made with the inventory data show that these corrections – mainly in the Top-Down process – are quantitatively not relevant. As a consequence, it is possible to obtain the emissions between 1970 and 2000 with a precision equivalent to that of the Brazilian Inventory.

The Final Report was delivered to the Ministry of Science and Technology – MCT and is available in our electronic address http://ecen.com. This article presents in a concise way some of the results obtained. Other results will be presented in the next issues of this periodical.

The period examined is from 1970 to 2000, corresponding to that of the data available at the Brazilian Energy Balance (BEB), published by the Ministry of Mines and Energy[1], when the project was executed and they were used by the present study.

2. Methodology

The Carbon Balance will try to establish an accounting of the net input and output of carbon in the activities concerning energy sources. The scheme is analogous to that adopted by BEB and is shown in Figure 1.

Figure1: Brazilian Energy Balance Scheme. Source: BEB/MME

Strictly speaking, one could make a carbon balance in each of the steps of the scheme above. The present study is concentrated on the centers of energy transformation and consumption. The treatment of the previous steps is certainly of interest for calculating the balance but it would involve data that are not available at BEB. For example, it would be important to know the characteristics of imported petroleum and of that internally produced in order to check the carbon content at the refineries’ input.

The values used in that balance are originally given in natural units that correspond to those used at the origin of information (mass in tones and volume in m3). In some cases, when the sources are grouped, the units are in tones equivalent petroleum (tep) and a special criterion must be established in order to calculate the emissions.

For the input data, it is necessary to evaluate the mass (or volume) of the emitted gases, its carbon content and the mass of this element that is eventually retained. Whenever available, one must also account for the losses provided that they are a real evaluation; when they are a simple record of the accounting differences, the carbon balance will calculate them. The methodology to compile the results was the object of the previous e&e-MCT agreement (ONG Nº 01.0077.00/2003) and is described in the reports presented whose abstract was published in the e&e periodical.[2].

In the methodology adopted, the emissions are calculated multiplying the values relative to the final use of the energy sources and to some transformations, expressed in energy, by coefficients calculated by surveying the inventory of greenhouse effect gases emissions in Brazil[3]. The coefficients used in the years before the period of the inventory calculation are those used for the first year when it was calculated (1990). The coefficients for the years subsequent to 1999 are those corresponding to that year (last year of the inventory).

For hydrocarbons, an approximation for the carbon content by contained energy can be obtained from the difference between the high and low heat values given by BEB. The methodology and its verification for gasoline was shown in the No 43 issue of this periodical (http://ecen.com/eee43/eee43p/ecen_43p.htm) and that of natural gas, in the present issue. The differences between the heat values fundamentally corresponds to the (latent) heat liberated in the condensation of water vapor formed in the combustion of one unit of fuel mass and the heat removed from the condensed water in order to reduce it to the ambient temperature, considered as 25º (540+75 cal/gwater). The difference between the heat values permits to deduce the quantity of water that is formed and consequently the hydrogen contained per unit mass of the fuel. The participation of carbon (in the case of hydrocarbons) is the complement of this participation.

3. Carbon Content in Energy Sources.

The elaboration of carbon balance requires firstly the conversion of BEB's data to carbon mass. The second step is to calculate the emissions that contain carbon.

Both in the carbon content calculation and the emissions evaluation, it is sometimes convenient to have data that are more detailed than that published in BEB's annex pages. It is convenient, for example, to have natural gas as humid and dry gas, hydrated and anhydrous alcohol as well as sugarcane compounds (sugarcane juice, bagasse and molasses) data.

The Ministry of Mines and Energy (MCT) published in 2002 balance data for 49 energy sources and 46 “accounts”[i]. Economy and Energy – NGO made a computer program (in Visual Basic and Excel) called ben_ee, where these data can be obtained in final or equivalent energy, in partial or complete tables. The energy source data can be represented in ton equivalent petroleum (tep) in the concept previously adopted by BEB and in the present one[ii], in Low Heat Value (LHV) and High Heat Value (HHV) and in “natural units” (mass and volume).

As part of the present agreement, the computer program was updated for the available data (1970- 2002) and they are also expressed in carbon content by using coefficients (mass C/energy) for each energy source. The annual data (in energy) are therefore converted to contained carbon and can now also be used for the set of years and generate temporal series.

In another approach that incorporates the Bottom-Up approximation results, the consolidated energy balance results (24 energy sources) and the values calculated by the MCT staff that elaborated the national emissions inventory published in the “Brazilian Communication to the United Nations Framework on Climate Change”[iii], were used to calculate the emission coefficients by energy source in each of the economic sectors presented in the balance (consumption) and transformation centers where there are direct emissions.

Using the above mentioned program denominated ben_eec (equivalent energy and carbon balance in the present version), tables with the carbon content by “account” and by energy source as normally presented in BEB were produced.

Comparing the results of the two methodologies, one can evaluate the validity of the carbon mass/energy coefficients used and the eventual errors or omissions in the inventory calculation. The carbon balance will also permit the extrapolation of emission values in the years before and after the inventory period (1990-1994) with more assurance.

It is hoped that the first set of results will be very similar to that corresponding to the Top-Down calculation recommended by the IPCC. The difference should only be the quantity of carbon retained (in the energy source uses) and in the non-oxidized carbon. In an easy way, it is possible to obtain emission values corresponding to this methodology from the results generated in this program. The program and its manual are available at http://ecen.com

Calculation of the Carbon Content

The ben_eec program presents the high and low heat values supplied by the MME. These values could be used for obtaining the carbon content as shown in Annex 1 of the Final Report. Even though the results for the year 2002 have been promising, some important differences were found. Besides that, as the objective of the present work is to develop a methodology and make a diagnosis, we have opted in the present step to use the same coefficients values used previously for calculating the emissions inventory. For this reason, we have used the coefficients of COPPE’s report to the General Coordination of Climate Change[4] that are, most of them, those values recommended by the IPCC[5]. It should be pointed out that the emissions values found in that reference are those that have been adopted by the already mentioned Brazilian National Communication.

In Table 1 are presented the results of the methodology application based on the heating values and the coefficients used in the present report (actually the same as those of COPPE’s report to the MCT mentioned above).

Table 1: Carbon content using the high and low heating values compared with values based on the IPCC values

Year 2002

 

HHV

LHV

KgH2O/

kgH/

KgC/

Mass of C  / Energy

 

 

 

KgFuel

KgFuel

KgFuel

 

 

 

a

b

e=(a-b)4,18/
615

f=e/9

g=1-f

Calculated.

Used

 

kcal/kg

kcal/kg

 

 

 

tC/TJ

tC/TJ

Petroleum

10800

10180

1,0081

0,112

0,8880

20,9

20,0

Humid natural gas(1)

11717

11130

0,9545

0,106

0,8939

19,2

15,9

Dry natural gas(1)

11735

11157

0,9398

0,104

0,8956

19,2

15,3

Steam coal

3100

2950

0,2439

0,027

0,9729

 

25,8

National metalurgical coal

6800

6420

0,6179

0,069

0,9313

 

25,8

Imported metalurgical coal

7920

7400

0,8455

0,094

0,9061

29,2

25,8

Picked wood

3300

3100

0,3252

0,036

0,9639

 

29,9

Commercial wood

3300

3100

0,3252

0,036

0,9639

 

29,9

Sugarcane juice

0

623

-1,0130

-0,113

1,1126

 

20,0

Molasses

0

1850

-3,0081

-0,334

1,3342

 

20,0

Sugarcane bagasse (3)

2257

2130

0,2065

0,023

0,9771

 

29,9

Leaching

3030

2860

0,2764

0,031

0,9693

 

20,0

Diesel oil

10700

10100

0,9756

0,108

0,8916

21,1

20,2

Average fuel oil

10080

9590

0,7967

0,089

0,9115

22,7

21,1

 

Year 2002

 

HHV

LHV

KgH2O/

kgH/

KgC/

Mass of C  / Energy

 

 

 

KgComb

KgComb

KgComb

 

 

 

a

b

e=(a-b)4,18/
615

f=e/9

g=1-f

Calculated.

Used

 

kcal/kg

kcal/kg

 

 

 

tC/TJ

tC/TJ

Automotive gasoline

11170

10400

1,2520

0,139

0,8609

19,8

18,9

Aviation gasoline

11290

10600

1,1220

0,125

0,8753

19,7

19,5

Liquefied petroleum gas

11740

11100

1,0407

0,116

0,8844

19,0

17,2

Naphtha

11300

10630

1,0894

0,121

0,8790

19,8

20,0

Illumination kerosene

10940

10400

0,8780

0,098

0,9024

20,7

19,6

Aviation kerosene

11090

10400

1,1220

0,125

0,8753

20,1

19,5

Coke plant gas (4)

4500

4300

0,3252

0,036

0,9639

 

18,2

Town gas
Rio de Janeiro (4)

3900

3800

0,1626

0,018

0,9819

 

18,2

Town gas São Paulo (4)

4700

4500

0,3252

0,036

0,9639

 

18,2

Mineral coal coke

7300

6900

0,6504

0,072

0,9277

32,1

30,6

Vegetal coal

6800

6460

0,5528

0,061

0,9386

 

29,9

Anhydrous ethyl alcohol

7090

6750

0,5528

0,061

0,9386

 

14,81

Hydrated ethyl alcohol

6650

6300

0,5691

0,063

0,9368

 

14,81

Refinery gas

8800

8400

0,6504

0,072

0,9277

26,4

18,2

Petroleum coke

8500

8390

0,1789

0,020

0,9801

27,9

27,5

Other petroleum
energy sources

10800

10180

1,0081

0,112

0,8880

20,8

20,0

Other Secondary - Tar

9000

8550

0,7317

0,081

0,9187

26,2

20,0

Asphalt

10300

9790

0,8293

0,092

0,9079

22,1

22,0

Lubricants

10770

10120

1,0569

0,117

0,8826

20,8

20,0

Solvents

11240

10550

1,1220

0,125

0,8753

19,8

20,0

Other petroleum Non-Energy

 

10800

10180

1,0081

0,112

0,8880

20,8

20,0

Results for the Contained Carbon

The ben_eec program supplies the contained carbon by “account” and by energy source. In Table 2 are given the contained carbon values in the energy sources of the Energy Balance for petroleum and its products (including the liquids from natural gas), for natural gas and for mineral coal and its products. It is also shown the sum of the carbon mass from fossil fuels and that from biomass. The values obtained are compared with the national inventory and they show good agreement.

Table 2: Carbon Content in Energy Sources Used in Brazil from 1970 to 2002

 

PETROLEUM AND ITS PRODUCTS

 NATURAL GAS 

. MINERAL COAL AND ITS PRODUCTS

FOSSIL FUELS

BIOMASS

TOTAL

1970

21068

123

2595

23786

44399

68185

1971

23396

192

2613

26201

44645

70846

1972

26103

215

2784

29101

45705

74806

1973

31311

241

2737

34289

45818

80108

1974

34607

359

2914

37880

46705

84585

1975

36603

397

3459

40460

46874

87334

1976

40186

441

3640

44266

45998

90264

1977

40933

527

4668

46128

46696

92824

1978

44712

630

5421

50763

46240

97003

1979

47451

655

5868

53975

48244

102219

1980

46432

733

6403

53568

50388

103955

1981

42538

709

6181

49428

50354

99782

1982

42509

941

6574

50024

50683

100707

1983

39832

1273

7401

48505

55525

104030

1984

38983

1609

9143

49735

61072

110807

1985

41368

1966

10799

54133

62778

116911

1986

45312

2298

10916

58526

62129

120655

1987

46318

2606

11537

60461

65387

125849

1988

47359

2714

11851

61923

63783

125706

1989

48068

2854

11745

62667

63799

126466

1990

48205

2909

10326

61441

58103

119544

1991

49282

2927

11978

64187

57287

121473

1992

50771

3088

11642

65501

56134

121635

1993

52751

3306

12051

68107

55602

123709

1994

55725

3415

12426

71565

58742

130307

1995

58957

3609

13150

75717

56595

132312

1996

64639

3957

13687

82282

56472

138754

1997

68738

4345

13911

86994

58465

145459

1998

72024

4534

13659

90217

57886

148103

1999

73149

5156

13873

92178

59275

151453

2000

72662

6813

14856

94331

55613

149944

2001

73866

8289

14643

96798

58001

154799

2002

71547

9803

14356

95706

62280

157985

Table 3: Comparison between the Obtained Carbon Content and those of the Brazilian Inventory

 

Present study

COPPE for  MCT

 

FOSSIL FUELS

BIOMASS

TOTAL

FOSSIL FUELS

BIOMASS

TOTAL

1990

61441

58103

119544

62345

58567

120912

1991

64187

57287

121473

64903

57716

122619

1992

65501

56134

121635

66259

56587

122846

1993

68107

55602

123709

68832

56063

124895

1994

71565

58742

130307

72311

59122

131433

Figure 2 represents the evolution of the contained carbon in the energy sources used in Brazil compared with that of the national inventory

Figure 2: Carbon content in the energy sources used in Brazil obtained in the present work compared with data from the National Inventory.

 Figure 3 shows the evolution of the carbon content of energy sources used in Brazil by primary fossil energy and in biomass

Figure 3: Carbon contained in the energy sources for the main fossil fuels and biomass

Table 4 shows data for 1994 using the division shown in BEB’s annexes. Annex 3 of the Final Report contains additional tables for selected years. Tables in this and other formats for additional years can be generated by the program that is annexed to this report.

It is worth while to notice that in the way that the program was made, it can produce almost immediately a Top-Down evaluation of the emissions that contain carbon. The result of such an evaluation is very close to the data corresponding to the line “Gross Internal Offer” of the spreadsheet (49 energy sources) that generated Table 4 (24 energy sources). The program evaluates the quantity of carbon retained in the non-energy uses of the fuels using factors suggested by IPCC and subtracting this quantity from the corresponding item.

More precisely, it would be necessary to use two more lines of the spreadsheet to subsidize the calculations. Using the Non-Energy Final Consumption line, one evaluates the carbon retained in the non-energy uses. The “Total Transformation” line can be used to evaluate an oxidation coefficient in cases where the data “division” used (49X46) has more than one IPCC coefficient. This occurs only in the cases of natural gas (liquids of natural gas and dry gas) and firewood (coal production and other uses).

In Table 5 the results obtained by the Top-Down (COPPE/MCT) process are compared with those calculated here using the carbon content table. It should be noted that the present work has used the same data source used by COPPE for the MCT but the data supplied by the MME are different. Particularly, it is already possible to use here the low heat value (LHV) adopted by BEB for defining the ton equivalent petroleum (tep) which was not available in the previous evaluation.

Since the aim of the present report is not to evaluate the emissions, some small divergences were not entirely elucidated and they may be due to energy source data or to how to group smaller fractions of the energy flux[iv]. The comparison results were encouraging, with average deviations smaller than 1% that are doubtless much smaller than those implicit in the adopted methodology.

Therefore, it is possible to make an evaluation of the emissions in the long 1970-2002 period that is presented in what follows.

Evaluation of Emissions between 1970 and 2002 or the Use of the Top-Bottom Process 

The IPCC methodology was adapted to directly calculate data generated by the ben_eec program. Three lines of the spreadsheet shown in Table 4 were used, namely:

·          Gross Internal Offer

·          Total Transformation

·          Non- Energy Final Consumption

It should be mentioned that the Top-Down methodology starts from the principle that the number of carbon atoms is conserved along the several interactions that finally will result in CO2 emission or of any other gas containing carbon. The IPCC methodology is directed to evaluating the carbon dioxide production.

This methodology consists of accounting for the primary and secondary fuels that enter in the economic system of a country in order to satisfy the needs of human activities (even the non-commercial ones) and that leave the system (retention in materials, net exports and non-oxidation).

Table 4:  Contained Carbon by Type of Fuel and “Account” – Gg/Year 2002

Table 4:  Contained Carbon by Type of Fuel and “Account” – Gg/Year 2002 (suite)

In order to avoid double counting, the raw materials produced or imported as well as the products exported or imported are accounted for; the transformations (of primary into secondary energy) carried out in the country should not be considered, as the carbon has already been computed in the raw material.

The gross internal offer concept actually corresponds to that adopted by IPCC where stock variations and re-injections are accounted for. It excludes as well the production losses that may however be evaluated from the spreadsheet generated by ben_eec.

The retained carbon, accounted for in the Top-Down methodology is that corresponding to the non-energy use. In this type of use carbon is not always retained and the IPCC methodology recommends the use of some coefficients (mass percent) in order to take into account the emission by natural evaporation (and subsequent conversion to CO2 in the atmosphere) or by waste burning or degradation. When they are not supplied, one can use evaluated coefficients based on available information. In the present case we have opted, whenever possible, for the values used in the mentioned COPPE/MCT report. The values used in the reference report were 0.8 for naphtha, 0.5 for lubricants, 0.75 for tar and 0.33 for dry natural gas. For other compounds the value 1 was adopted (all carbon retained). In Table 5 the calculation process is illustrated for the year 1994. [v]

Table 5: Emissions Calculation using the IPCC Top-Down Method  1994 Gg/Year

Table 5: Emissions Calculation using the IPCC Top-Down Method (Suite)

In Table 6 a example of CO2 Emissions calculation using three outputs lines of the carbon content table is shown.

 Table 6: Example of CO2 Emissions Calculation using Output Lines of the Program

 

 GROSS OFFER
(a)     

TOTAL TRANS-FORMATION (b)

 NON ENERGY FINAL  CONSUMPTION (c)

Retention Coefficient (d)

Oxidation Coefficients

(e)

Retained Carbon (f=cxd

Net Carbon Emissions ^(g=a-f)

e Carbon Emissions (h=gxe)

CO2 Emissions (i=hx44/12

PETROLEUM

52726

-54326

0

0,00

0,99

0

52726

52198

191394

HUMID NAT GAS

3478

-3426

0

0,00

0,994

0

3478

3456

12670

DRY NAT GAS

-63

2437

630

0,33

0,995

208

-271

-270

-989

VAPOUR COAL

2126

-1188

0

0,00

0,98

0

2126

2083

7639

NAT. MET. COAL

82

-82

0

0,00

0,98

0

82

81

296

IMP. MET COAL

8937

-8609

0

0,00

0,98

0

8937

8758

32113

OTHER NON REN.

0

0

0

0,00

0

0

0

0

0

FIREWOOD

31108

-13883

0

0,00

0,880

0

31108

27356

100305

SUGARCANE JUICE

4970

-4970

0

0,00

0,99

0

4970

4920

18040

MOLASSES

884

-884

0

0,00

0,99

0

884

875

3207

SUGARCANE PULP

18794

-590

0

0,00

0,88

0

18794

16539

60642

LEACHING

1828

-351

0

0,00

0,99

0

1828

1809

6634

OTHER RECOV.

687

-315

0

0,00

0,994

0

687

683

2504

DIESEL OIL

1554

18737

0

0,00

0,99

0

1554

1538

5641

FUEL OIL

114

10023

0

0,00

0,99

0

114

113

414

GASOLINE

-1710

9461

0

0,00

0,99

0

-1710

-1693

-6206

LPG

1401

3273

0

0,00

0,99

0

1401

1387

5084

NAPHTHA

1944

3403

5136

0,00

0,99

4108

-2165

-2143

-7859

 ILLUM. KEROSENE

-3

111

26

0,80

0,99

26

-29

-28

-104

AVIATION KEROSENE

-214

1929

0

1,00

0,99

0

-214

-211

-775

REFINERY GAS

-67

1810

166

0,00

0,99

166

-233

-231

-846

PETROLEUM COKE

-19

636

0

1,00

0,99

0

-19

-19

-69

OTHER PETROLEUM

0

649

0

0,00

0,99

0

0

0

0

TOWN GAS

0

140

0

1,00

0,99

0

0

0

0

MIN. COAL COKE

1322

7301

0

0,00

0,99

0

1322

1295

4749

COKE PLANT GAS

-41

1196

0

0,00

0,98

0

-41

-41

-149

OTH.SEC. TAR

0

231

64

0,00

0,99

64

-64

-63

-231

VEGETAL COAL

-2

3440

0

1,00

0,99

0

-2

-2

-7

ANYDROUS ALCOHOL

150

926

41

0,00

0,99

41

109

107

394

HYDRATED ALCOHOL

323

3069

292

1,00

0,99

292

31

31

112

ASPHALTS

-22

1186

1176

1,00

0,99

1176

-1198

-1186

-4349

LUBRICANTS

-24

599

535

1,00

0,99

535

-559

-553

-2029

SOLVENTS

29

285

297

1,00

0,99

297

-268

-265

-973

OT.NON   EN.PET.

16

710

736

1,00

0,99

736

-721

-714

-2616

PET.  NG 

AND RODUCTS

2999

52951

8073

1,00

0,99

7253

-4254

51379

188388

MIN. COAL

 AND PROD..

12426

-1152

64

0,00

 

64

12362

12114

44416

FOSSILS

15425

51799

8136

0,00

 

7317

8107

63492

232805

RENEWABLE

58742

-13557

334

0,00

 

334

58408

52318

191831

TOTAL

130307

-17072

9100

0,00

 

7651

122656

115810

424636

In Table 7 the net emissions (carbon content – retained carbon) are shown for the other years separated into fossil fuels and biomass. The values calculated for the national inventory are also compared in Table 8 with those obtained here.

    Table 7: Net Emissions in Gg/year of Carbon

 

PETROLEUM AND PRODUCTS

NATURAL GAS

MIN. COAL AND PRODUCTS

FOSSIL

RENEWABLE

TOTAL

1970

20053

122

2560

22735

44268

67003

1971

22397

188

2573

25158

44544

69701

1972

24707

205

2742

27655

45605

73260

1973

29671

227

2691

32590

45730

78319

1974

32241

343

2871

35456

46589

82045

1975

34152

380

3405

37937

46756

84693

1976

37528

413

3577

41518

45898

87416

1977

38028

504

4630

43162

46565

89727

1978

41077

569

5335

46980

46122

93103

1979

43049

584

5792

49424

48137

97561

1980

42611

649

6303

49563

50232

99795

1981

38891

649

6091

45631

50223

95854

1982

38272

852

6457

45581

50558

96139

1983

35469

1124

7259

43852

55284

99136

1984

34366

1446

8960

44772

60854

105626

1985

35543

1790

10620

47953

62520

110473

1986

39558

2105

10727

52390

61888

114278

1987

40175

2400

11432

54007

65164

119170

1988

41287

2506

11794

55587

63570

119156

1989

41919

2628

11689

56236

63565

119801

1990

41821

2733

10235

54789

57799

112588

1991

43224

2742

11878

57845

57069

114914

1992

44490

2894

11602

58986

55913

114899

1993

46346

3113

12004

61463

55319

116782

1994

48680

3207

12362

64248

58408

122656

1995

52109

3432

13095

68636

56216

124852

1996

57644

3794

13547

74985

56114

131099

1997

60561

4295

13726

78582

58139

136721

1998

63397

4455

13500

81352

57510

138862

1999

64144

5006

13759

82908

58896

141804

2000

63187

6658

14738

84583

55218

139801

2001

64999

8141

14528

87669

57583

145252

2002

62866

9661

14255

86782

61984

148766

     Table 8: Comparison of Net Carbon Emissions Results (Gg/year)

 

FOSSIL

 RENEWABLE

TOTAL

FOSSILCOPPE/MCT 2002

BIOMASS

COPPE/MCT 2002

TOTAL

1990

54789

57799

112588

55994

58264

114258

1991

57845

57069

114914

58851

57499

116350

1992

58986

55913

114899

60016

56367

116383

1993

61463

55319

116782

62472

55781

118253

1994

64248

58408

122656

65294

58789

124083

The fraction of oxidized carbon (that directly, or through degradation of other compounds in the atmosphere, generates CO2) varies according to the fuel. In the adopted methodology (Top-Down) this correction is carried out using a multiplying factor suggested by IPCC. In two cases (firewood for coal production versus firewood for direct burning and dry natural versus liquids from natural gas) there are specific coefficients. From the carbon mass involved in the transformation, one can calculate the participation of firewood in coal production and that of dry natural gas in consumption. The oxidized fraction for firewood and mineral coal can be obtained and the complement is computed in the other use of each energy source. Using the consumption participation share of humid natural gas (raw material) as dry gas (in the example with 71.1% participation share and 99.5% oxidation) and the consumption complement as natural gas liquids (28.9% with 99% oxidation), one estimates an average coefficient for firewood and humid natural gas that is the weighted average between the two original coefficients. This coefficient is recalculated in each year using the participation shares.[vi]

Table 9 shows the annual results obtained here by primary source and for biomass. The results are compared with the values of the National Inventory in Table 10.

Table 9: CO2 Emissions in Gg/year for Brazil

 

PETROLEUM AND ITS  PRODUCTS    

NATURAL GAS

MINERAL COAL AND PRODUCTS

FOSSIL

 RENEWABLE

TOTAL

1970

72791

446

9194

82431

141858

224289

1971

81301

683

9242

91226

142808

234034

1972

89688

746

9852

100285

146324

246609

1973

107707

825

9669

118201

146755

264956

1974

117036

1250

10313

128600

149609

278208

1975

123971

1384

12233

137588

150235

287822

1976

136228

1504

12848

150580

147486

298067

1977

138041

1837

16635

156513

149824

306337

1978

149109

2071

19166

170346

148686

319032

1979

156267

2126

20808

179201

155524

334724

1980

154679

2364

22643

179686

162572

342258

1981

141174

2363

21882

165419

162582

328001

1982

138927

3104

23197

165229

164015

329243

1983

128752

4093

26078

158923

179750

338673

1984

124748

5267

32189

162204

198142

360346

1985

129022

6519

38152

173693

203967

377661

1986

143596

7669

38536

189801

202281

392082

1987

145835

8744

41073

195651

213061

408713

1988

149870

9127

42377

201374

208044

409418

1989

152165

9570

42000

203735

208180

411915

1990

151811

9952

36772

198535

189462

387998

1991

156905

9984

42678

209567

187242

396809

1992

161499

10541

41686

213726

183505

397231

1993

168236

11337

43133

222705

181714

404419

1994

176707

11681

44416

232805

191832

424637

1995

189157

12500

47050

248708

184746

433454

1996

209249

13820

48673

271743

184568

456311

1997

219838

15646

49315

284798

191153

475951

1998

230133

16230

48503

294865

189000

483865

1999

232841

18234

49435

300510

193589

494099

2000

229368

24250

52952

306570

181548

488118

2001

235948

29643

52200

317791

189149

506940

2002

228203

35179

51218

314601

203571

518172

Table 10: Comparison of CO2 Emissions in Gg/year for Brazil calculated in the present work with those of the inventory

 

FOSSIL

 RENEWABLE

TOTAL

FOSSIL

COPPE/MCT 2002

BIOMASS COPPE/MCT 2002

TOTAL

1990

198535

189462

387998

202910

190575

393485

1991

209567

187242

396809

213220

188221

401441

1992

213726

183505

397231

217466

184521

401987

1993

222705

181714

404419

226369

181676

408045

1994

232805

191832

424637

236599

192636

429235

Figure 4: CO2 emissions obtained by the Top-Down methodology adapted to the program’s output format.

The agreement between the data obtained here (for the available years) and those of the inventory is very good. It should be pointed out that the calculation routine of the program is completely equivalent to that of IPCC, as demonstrated in Table 5. The small observed differences should be ascribed to the low heat values that in the present approximation are those adopted by BEB and they were not available at the time the inventory was made; there are also small doubts concerning the energy allocations relative to the IPCC methodology. The program developed here is therefore a powerful tool for evaluating the past and projected balances. It can be very useful as well for calculating the inventory of countries that have not made it yet. In future studies, a program that presents graphics and tables for the inventory can be.

References:


 

[i] The  “accounts” concept corresponds, in the Brazilian Energy Balance (BEB), to accounting points that could be consumption or transformation centers and operations reference to availability (gross offer) of energy sources (production, exports, imports, etc.)

[ii] In the program the terms “old tep” (10,8 Gcal) and “new tep” (10,0 Gcal) were adopted in order to distinguish the two types of values.

[iii] In what follows, the terms National (or Brazilian) Inventory and National Communication refer to this document and the inventory it contains.

[iv] The uncertainties associated with natural gas and alcohol should be calculated, since problems may occur regarding the heat values used.

[v] According to the authors of the present study, the use of unitary values (100% retention) deserves a revision, mainly for volatile products such as alcohol and solvents.

[vi] Within the margin of errors in an evaluation as that of emissions, it would be acceptable the use of the same coefficient for all the years. However, we have tried in the methodology adopted here to make it completely equivalent to that of IPCC and an annual coefficient was calculated for each year for both energy sources.


 

[1] __________  MME, Balanço Energético Nacional 2003

[2]  Carlos Feu Alvim et al. (relatório do projeto)

[3] _________ Coordenação-Geral de Mudanças Globais de Clima – MCT “Comunicação Nacional Inicial do Brasil à Convenção das Nações Unidas, “Brasília Novembro de 2004

[4] _________ COPPE – UFRJ e MCT; Primeiro Inventário de Emissões Antrópicas de Gases de Efeito Estufa” – Relatório de Referência – Emissões de Carbono Derivadas do Sistema Energético – Abordagem TopDown  MCT 2002

[5] IPCC, 1996. Greenhouse Gas Inventory Reporting Instructions - Revised IPCC Guidelines for National Greenhouse Gas Inventories, Vol 1, 2 , 3, IPCC, IEA, OECD.

 


 

 

 

Graphic Edition/Edição Gráfica:
MAK
Editoração Eletrônic
a

Revised/Revisado:
Tuesday, 11 November 2008
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