Economy & Energy
Ano II - No 11 November/December 1998

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ELECTRICITY IN THE BRAZILIAN ENERGY BALANCE – BEB

                                                                             João Antonio Moreira Patusco
                                                                                                          General Coordinator of Integrated Studies - MME
                                                            patusco@mme.gov.br
undercon.gif (1131 bytes)English Version Frida Eidelman
frida@password.com


TECHNICAL NOTE CGEI nº 01 /98 22/09/98

Approach: analysis of the relative participation of hydraulic power and electricity in the offer and consumption of energy in Brazil and comparison with other countries, taking into account different criteria for conversion factors for the common unit adopted.

 CONVERSION COEFFICIENT FOR HYDRAULIC POWER AND ELECTRICITY IN BEN

The ton-oil-equivalent (toe) is the common unit used to convert the measuring units of different forms of energy used in BEN. The conversion factors are calculated based on the superior calorific power of each energy source relative to that of petroleum, namely 10,800kcal/kg.

For hydraulic power and electricity offer and demand it is used the factor of 0.29 toe/MWh, resulting from the ratio between the average consumption of fuel oil in kcal/kWh in the Brazilian thermoelectric plants and the superior calorific power of petroleum (3,132/10,800). Therefore, it is the factor that represents the thermal equivalence of electrical generation.

Note: 3,132 kcal/kWh corresponds to a thermal generation average efficiency of 27.5%.

Should the theoretical criterion for hydraulic power and electricity be used, where kWh =860kcal (according to the first principal of thermodynamics), the conversion factor would be 0.08 toe/MWh (860/10,800), therefore 3.62 times smaller than the one used in BEN.

Note: the use of the superior calorific power barely modifies the results in toe, since in order to calculate the conversion factors, the numerator and denominator are practically proportionally altered.

 HISTORICAL PRECEDENTS

At the start of the seventies, when the first reports containing energy data consolidation were started in Brazil, the international literature on energy balance indicated for hydraulic power the preponderant use of thermal equivalence factor. This criterion was based on making comparable the offer of energy from countries with high and low participation of hydraulic generation. Therefore, hydraulic power factors varying from 0.20 to 0.30 toe/MWh were used, depending on the average efficiency of the thermal power plants.

For the offer and consumption of electricity, the theoretical criterion was used, namely, 0.080 toe/Mwh. Therefore, the consolidated balances presented high losses (fictitious) by transforming hydraulic energy into electricity, due to accounting hydraulic power as thermal equivalency. By the previous reason, Brazil adopted for electricity offer and demand the same criterion of thermal equivalence (0.29 factor).

As a matter of fact, from the seventies on the international energy balances have substituted the thermal equivalence criterion by the theoretical one in hydraulic power accounting, which did not occur in BEN/BR. As examples we mention the recent energy balances from the International Energy Agency, the World Energy Council, the Latin-American Energy Organization, etc. The thermal equivalence criterion is applied only to nuclear, solar, wind and geothermal energies.

EFFECTS OF CONVERSION FACTORS FOR HYDRAULIC POWER AND ELECTRICITY ON BEB

Table 1 presents 1997 data from the Brazilian Internal Energy Offer – IEO, considering both accounting criteria for hydraulic power and electricity – h&e (0.29 and 0.08 conversion factors).

TABLE 1

INTERNAL ENERGY OFFER -1997

  HYDR. and ELEC.=0.29 HYDR. and ELEC. =0.08
SOURCES 10´ 3 toe % 10´ 3 toe %
NON-RENEWABLE ENERGY 100418 41.4 100418 57.2
PETROLEUM AND ITS PRODUCTS 81441 33.5 81441 46.4
NATURAL GAS 6376 2.6 6376 3.6
URANIUM (U3O8) AND ITS PRODUCTS 286 0.1 286 0.2
MINERAL COAL AND ITS PRODUCTS 12315 5.1 12315 7.0
RENEWABLE ENERGY 142351 58.6 75249 42.8
HYDRAULIC POWER AND ELECTRICITY 92665 38.2 25563 14.6
WOOD AND VEGETAL COAL 21913 9.0 21913 12.5
SUGAR CANE PRODUCTS 24670 10.2 24670 14.0
OTHER PRIMARY
RENEWABLE SOURCES
3103 1.3 3103 1.8
TOTAL 242769 100.0 175667 100.0

 As one can notice, the IEO changes from 242.7 million toe by the thermal equivalence criterion to 175.7 million toe by the theoretical criterion – a reduction of 28%. Still by the theoretical criterion, h&e changes its participation in the IEO from 14.6% to 38.2%, according to the other criterion – 23,6 percent points less. As a consequence, the renewable energy has also its relative participation considerably reduced, loosing 15.8 percent points.

The graphic below shows the evolution indexes of the GNP and of IEO, the last one according to both criteria for h&e, taking 1970 as basic year.

EVOLUTION INDEXES OF GNP AND IEO

pibene.gif (7522 bytes)

Since h&e was the energy source group that had the largest growth in the period 1970/1997, one can observe, due to the fact that its conversion factor is diminished, the IEO presents smaller growing rates, showing in the period an elasticity smaller than one, relative to the GNP.

 

EVOLUTION OF ENERGY AND GNP

An analysis of the effects on the final energy consumption can be made through the data from table 2 where it is also introduced the concept of useful energy, namely the calculation of the relative participation considering the use efficiency of the energy sources in the final use equipment such as boilers, furnaces, dryers, motors, etc.

 TABLE 2

FINAL ENERGY CONSUMPTION – 1997

 

Elect. = 0.29

Elect. = 0.08

Useful energy

SOURCES

10´ 3 toe

%

10´ 3 toe

%

10´ 3 toe

%

ELECTRICITY

85702

40.9

23642

16,0

18204

23,5

PETROLEUM PRODUCTS

67416

32,1

67416

45,6

30127

38,9

NATURAL GAS

4181

2,0

4181

2,8

2801

3,6

MINERAL COAL

9855

4,7

9855

6,7

7239

9,3

BIOMASS

42639

20,3

42639

28,9

19138

24,7

TOTAL

209793

100,0

147733

100,0

77509

100,0

It can be noticed that electricity has its participation abated by using the theoretical criterion but recuperates part of the participation when calculated in useful energy. This is due to the larger efficiency of the equipment used in electricity relative to the national average.

Compared to other countries and considering the theoretical criterion, the data of table 3 show that Brazil presents electricity participation in the final energy consumption similar to that of the developed countries, between 15% and 20%. Nevertheless, from the point of view of the offer, when one analyses the origin of electricity for the different countries, it is noticed that in Brazil, due to the high hydroelectricity, only 16.8% of the internal energy offer – IEO – is intended for electricity while other countries have this value between 32% and 40%. As a consequence, these countries present high loses in transformation – energy quantities between 18% and 28% of the IEO ( themoelectric generation losses).

TABLE 3

ELECTRICITY IN SOME COUNTRIES

SPECIFICATION

UNIT

GERMANY

JAPAN

USA

BRAZIL

Electricity consumption/ Final consumption

%

16.0

20.4

14.7

16.0

Consumption in electric generation /I EO

%

35.1

39.6

32.4

16.8

Thermal generation / IEO

%

34.7

38.0

31.3

2.8

Hydro generation / IEO

%

0.4

1.6

1.1

14.0

Hydro generation / Total generation

%

3.2

10.1

8.7

94.0

Losses in transformation /IEO

%

27.5

26.5

18.6

6.2

CONCLUSIONS

In the energy prospective studies, where the competition possibilities among energy sources are analyzed, the end use, the equipment efficiency and captive uses are the variables used and therefore, for electricity, the theoretical criterion is valid. Therefore, from the technical point of view, there is no restriction on using one or the criterion for representing the figures of hydraulic power and electricity in Energy Balances.

Advantages of maintaining the 0.29 toe/MWh factor:

  1. as a habit, we are used to considering the IEO of Brazil as being composed by the famous tripod – petroleum, hydraulic power and biomass. The use of the theoretical criterion would uncharacterize this affirmation.
  2. the electric sector, in some way, has used the relative importance of electricity in the final energy consumption in order to enhance the need of investments for expansion.
  3. more equitable comparison of the Brazilian per capita IEO with those of other countries that presented significant thermal generation.

Disadvantages of maintaining the 0.29 toe/MWh factor:

  1. difficulty in comparing energy data from Brazil with data from other countries. It is usual to compare data from BEN with data from other countries without mentioning the conversion factor criteria.
  2. the smaller participation of the other energy sources in the IEO and final consumption.
  3. application of two criteria on BEN since the theoretical criterion must be used in the electrical power plants tables (Tables 5.3 and 5.4), price tables (Tables 7.10 and 7.11) and tables with data from other countries (tables B1 and B2).
  4. In Annexes F01 to F28 of BEN – Consolidated Energy Balances – the data from Public Electrical Power Plants and Self-producers do not show the real efficiency of thermal generation.

AUTHOR’S SUGGESTIONS

Gradual introduction of the theoretical criterion in BEN, initially with simultaneous presentation of both criteria in some tables of chapter 1 (including that of useful energy) and extensive distribution of this Technical Note in BEN itself and via Internet.

SOME CONCEPTS

Measurement Units (Commercial) – units that usually express the commercialized quantities of energy sources, for example: for solids, ton (t) or pound (lb), for liquids, cubic meter (m3) or barrel (bbl), for gases, cubic meter (m3) or cubic foot (ft3) and for electricity, watt(W) for power and watt-hour (Wh), for energy.

Common Unit – unit to which the measurement units used for different forms of energy are converted. This unit allows for adding different energy quantities in the Energy Balances. According to the International Unit System – IS, joule or kilowatt-hour are the regulated units used as Common Unit but other units are currently used by different countries and international organizations such as equivalent ton-oil-equivalent (toe), ton-coal-equivalent (tce), calorie and its multiples, British thermal unit (Btu), etc.

Conversion Factors (coefficient of equivalence) – coefficients that permit transforming quantities expressed in measuring quantities to quantities expressed in a common unit. For example, in the case of Brazil, in order to convert tons of wood into toe, the 0.306 coefficient is used, which is the ration between the calorific power of wood and that of petroleum (3,300 kcal/kg/ 10,800 kcal/kg), that is 1t of wood = 0.306 toe.

Calorie (cal) – quantity of heat in kcal necessary to raise the temperature of one gram of water from 14.5o C to 15.5 o C at normal atmospheric pressure (760 mm Hg).

Calorific Power – heat quantity in kcal produced by 1kg or 1m3 N of fuel after complete combustion.

Note: the fuels that produce H2O in the combustion products (derived from combustion or from impregnated water) have a superior calorific power and a lower calorific power. Since most of the time H2O escapes through the chimney as vapor, the inferior caloric power is the one that is practically significant.

watt (W) – Power unit – watt is the power of an energy system in which the energy of 1 joule is uniformly transferred during 1 second.

watt-hour – (Wh) – energy uniformly transferred during 1 hour.

1 Wh = 1 ´ 3,600 s ´ J/s= 3,600 J = 3,600 ´ (0.239 cal) = 860 cal

Therefore, in the theoretical concept 1kWh = 860 kcal

Note: watt, watt-hour and their multiples are measurement units used for hydraulic power and electricity, for power generation and distribution.

joule (J) – Work unit for energy and quantity of heat. Joule is the work produced by a force of 1 newton whose application point moves 1 meter in the force’s direction.

1 J = 1 N. m

newton (N) – Force unit. Newton is the force that, when applied to a body with 1 kilogram of mass, transmits the acceleration of 1 meter per second squared. Considering the acceleration of gravity as 9.806 m/s2, one has

1 N = 0.102 kg

Internal Energy Offer is the quantity of energy available for transformation and/or final consumption. Therefore it gives the energy before the transmission and distribution processes.

Final Energy Consumption is the energy consumed by the different sectors of the economy to satisfy the needs of different uses such as heat, motive power, illumination, etc. It does not include quantity of energy used as raw material for the production of any other form of energy.

Note: except for statistical adjustments, the difference between Internal Energy Offer and Final Energy Consumption correspond to adding the losses in distribution and storage to losses in the transformation processes (refineries, distilleries, electrical power plants, coking, etc.).