Economy & Energy
Year II - No 10
September/October 1998
Main Page
Bolivia- Brazil Gas Pipeline
Useful Energy Balance
The Brazilian Crisis
Thermoelectric Power Station in the north of Espirito
Santo
e&e Links
Graphic Edition:
MAK
Editoração Eletrônica
marcos@rio-point.com
Revised:
Sunday, 28 August 2005.
Production:
Ministry of Mines and Energy
Contacts: João Antônio Moreira Patusco
patusco@mme.gov.br
English Version
Frida Eidelman
frida@password.com.br
By useful energy one means the energy available to the consumer after the last conversion made in his own equipment. It is the final energy (energy supplied to the equipment) minus the conversion loses.
The identification of this useful energy permits to learn which economical sectors are energetically less efficient and which energy forms are used more efficiently, allowing therefore the implementation of programs for energy substitution and conservation.
The first study on useful energy at the national level was made in 1984 and applied to the final energy consumption by economical sector of 1983 from BEN and where the following final uses were considered: driving power, heat process, direct heating, lighting , electrochemistry and other uses.
In 1995, by initiative of MME, a new study on useful energy was concluded, applied to the final energy consumption of 1993 from BEN , incorporating the technological changes occurred in the period 1983/1993 and considering other consuming sectors such as aluminum, sugar and pelleting , not considered before. The study incorporates also a model for forecasting the potential of energy saving taking into account the reference efficiency (efficiency of the most modern equipment existing in each consuming sector in 1993).
In the following tables are presented the main results of the studies, detailed by sectors, energy and use. The columns in the tables are as follows:
• 1st column – average yield verified in 1983
• 2 nd column – average yield in 1983 utilizing the use efficiency of 1993
• 3 rd column – average yield verified in 1993
• 4th column – average yield in 1993 utilizing the reference efficiencies
The average yields are the quotient between the useful energy and the final energy and are affected by both the typical efficiency of each process and the distribution of the final energy use. Organized in this way, the tables permit to isolate the effects of improving the equipment’s efficiency (comparison of 1st and 2nd columns) and the effects of altering the consumption structure (comparison of 2nd and 3rd columns).
AVERAGE YIELD BY SECTOR -%
SECTORS 83 83/93 93 93R Energy 74 74 72 76 Residential 23 24 36 45 Public/Commercial/Agriculture 33 36 51 54 Industrial 61 65 67 71 Transportation 32 37 36 40 Total 44 48 52 58 AVERAGE YIELD BY USE - %
Uses 83 83/93 93 93R Driving Power 40 46 46 51 Process heat 66 69 70 74 Direct Heating 38 40 50 57 Others 22 27 32 41 Total 44 48 52 58 The tables show that from BEU/83 to BEU/93 the total energy yield changed from 44% to 52%, i. e., it increased 8 percent points.
AVERAGE YIELD BY SOURCE - %
Sources 83 83/93 93 93R Natural Gas/Gas/LPG 54 59 60 61 Vegetal Coal/Wood/Bagasse 35 36 48 55 Electricity 66 72 69 77 Fuel Oil 66 72 71 73 Gasoline/Kerosene/Diesel/Alcohol 32 37 36 40 Total 44 48 52 58 Half of this increase is due to the effective improvement on the equipment yield. The other half is due to the reduction on using less efficient fuel (wood, mineral coal, etc.) and by increasing the participation of more efficient fuel (LPG, natural gas, town gas, electric power, etc.).
By adopting for 1993 the reference equipment efficiency (without modification of the consumption structure), one gets an additional improvement in the total energy yield of 6 percent points (comparison of the 3rd and 4th columns).
SECTORIAL ANALYSIS
Energy Sector
Energy consumption in the Brazilian Energy Sector is centered in great part in two areas: petrol refining and alcohol distilleries. In the generation and distribution of electricity there is little final consumption of energy.
Petrol refining , which is the activity where energy is mostly consumed, has increase only 18% in the period 1983/93 ( about 1.7% annually).
Alcohol production has increased 43% (3.6% annually) in the same period.
Therefore, the use of bagasse from sugar cane – which is less efficient than other fuels – has caused a reduction on the average yield in the Energy Sector as a whole.
Residential Sector
The increase on the average yield was due to a series of factors, such as:
- the increase of the LPG participation (7 to 10 time more efficient than wood);
- the increase of 80% in the electrical energy consumption in the Sector (6% annually);
- the increase in participation of more efficient uses of electrical energy, for example: other uses (electronic appliances), the use as driving power (domestic appliances in general) and the use as process heat;
- the improvement of yield in final uses, such as driving power and lighting.
Public, Commercial and Husbandry Sectors
In general lines, these three sectors suffered a process similar to the one described in the Residential Sector:
- the increase of more efficient uses of electricity;
- improvement in the efficiency of electrical processes;
- the decrease of wood consumption (43% in the Commercial Sector, 83% in the Public Sector and 40% in Husbandry).
Transportation Sector
The use of energy in the Transportation Sector is identified with the use of driving power and with gasoline, kerosene, diesel and alcohol fuels, so that the observed modifications are in large part associated with the improvement on motor efficiency.
The reduction on the average yield of the 2nd and 3rd columns is due to the increase on the participation of gasoline and alcohol in the sector whose efficiencies are smaller than that of diesel.
Industrial Sector
In the Industrial Sector the average yield changed from 61% to 67%. About 4% is due to the increase of the equipment’s efficiency and the other 2 percent points are due to structural alterations on consumption.
These gains had contributions, for example, from the larger use of natural gas and electricity and also the growth of industrial segments that are more efficient in energy terms. It is important to emphasize that the expansion in the Industrial Sector has occurred with the installation of industrial plants that are more efficient than the existing ones.
CONCLUSIONS
The results of the studies show that there was a significant improvement on the average yield of energy use in the Brazilian Productive Sector. Therefore, it is verified that from 1983 to 1993 there has been an increase of only 28% (2.5% annually – electricity = 860 kcal/kWh) in terms of final energy, even though the increase on useful energy is estimated to be 51% (4.2% annually).
The GNP increase in the same period nevertheless was only 31% (2.7% annually) which seems to better correlate with the variation of final energy than that of useful energy.
In order to explain the elevated increase on useful energy consumption by GNP unit it is convenient to remember initially that not all of the useful energy is destined to productive activities. So, the useful energy share destined to the residential sector is not directly linked to the productive sector. This occurs also with part of useful energy destined to the public and transportation sectors. This energy is consumed to generate well being to the population, it is not linked to the productive activity.
Other fact that explains the increase in the energy intensity was the Brazilian option for the strong growth of energy-intensive segments with the capacity of generating Aggregated Value not proportional to the energy consumption (aluminum, steel, soda-chlorine, paper, and cellulose, fertilizers, etc.)
The present context of world economy in which some products had drastic price reductions have also contributed to this increase on intensity.
The following files are available for downloading:
Balanço de Energia Útil (Useful Energy Balance) only in Portuguese
Text - beutexto.zip 265 KB – generates Word files
Data 1993 beu93.zip 285 KB - generates Excel files
Data 1983 beu83.zip 384 KB - generates Excel file