Economy & Energy
  Year  I  - No 5
Nov/Dec 1997


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MAK
Editoração Eletrônic
a
marcos@rio-point.com
Revised:
Tuesday, 22 July 2003

Biomass and Electric Generation
Coordenadoria-Geral de Estudos Integrados
             MME/Brasil

João Antônio Moreira Patusco

patusco@mme.gov.br

BIOMASSA FOR COMBUSTION

At the start of the forties, biomass was responsible for about 83% of the Brazilian Internal Energy Offer- IEO, of which 81% corresponded to wood and 2% to sugar cane bagasse . Due to the growing use of petroleum products, together with hydroelectricity expansion, biomass contribution decreased decade after decade.

In 1970, starting year of the present National Energy Balance data base, biomass participated already with 47% in the IEO ( 42% with wood and 5% with bagasse). While wood was being substituted by petroleum products, mainly by LPG in the residential sector, sugar cane bagasse increased its importance in the energy matrix as a function of the increase of sugar and alcohol production, the latter from 1975 on.

INTERNAL ENERGY OFFER - %


Figure
Internal Energy Offer - 1940/96 10^6 tep
Mineral Coal and other Sugar Cane Products

wpe3.jpg (14964 bytes)


In 1996, the IEO was composed of 21.4% of biomass, of which 9.6% of wood, 10,2 % of sugar cane products (sugar cane juice, molasses and bagasse), 1.6% of leachates and other residues.

 Of the total biomass offer of 47 million tep in 1996, only 1.2 million (2.5%) were used in electric power generation. The details of this generation are shown in the following topic.

BIOMAS IN ELECTRIC GENERATION

According to data from the 1997 National Energy Balance, the electricity self production in 1996 was 16 TWh ( 3.9 hydro and 12.1 thermo), corresponding to 5.5% of the total generation in the country (290 TWh) and 12% of the industrial electricity consumption.


The metal works industry, with 28% of self generation, is the main electricity self producer, followed by the paper and cellulose industry, with 25%, the sugar - alcohol industry, with 12% and the chemical industry, with 11%. Other unspecified segments are responsible for the remaining 6% (mining, cement, etc.)

The following table shows that the sugar- alcohol industry produces about 80% of the electricity it consumes, followed by the petroleum sector, generating 54% of its needs and paper and cellulose, with 40%.


ELECTRIC ENERGY SELF PRODUCERS 1996

Sector Total Electricity
Consumption
(a)
TWh
Self Generation (b)
TWh
         (b)/(a) %
Metallurgy 50,5 4,5 8,9
Aluminum 19,2 2,3 12,0
Pig Iron and Steal 14,7 2,1 14,3
Ferroalloys 6,6 0,1 1,5
Others 10,0 0,0 ...
Paper and Cellulose 9,9 4,0 40,4
Sugar - Alcohol 3,7 2,9 78,4
Petroleum 3,5 1,9 54,3
Chemistry 15,1 1,7 11,3



Of 12.1 TWh thermal generation, biomass was responsible for 49.2% (6 TWh) of which 48% were generated from sugar cane bagasse (2.9 TWh), 38% from leachates (2.3 TWh) and 14% from wood and other vegetable residues ( barks, branches and leaves, 0.8 TWh). The sugar - alcohol sector is responsible for the use of bagasse and that of paper and cellulose, for the use of leachates, wood and residues.


The participation of bagasse in the thermal self generation has been following the sugar and alcohol production and the participation of leachates that of cellulose. As to wood and other residues, they showed a large increase between 1980 and 1985 due to the substitution of fuel oil in the cellulose industry. From 1986 on, due to the decrease of fuel oil prices, these energy source were less used.

THERMAL AUTO-GENERATION

SOURCES

1980

1985

1990

1996

Total - GWh

5539

6285

8793

12156

Biomass - %

33,5

51,4

43,3

49,2

Sugar cane bagasse-%

18,1

27,7

20,4

23,7

Leachates %

10,9

10,8

13,0

18,6

Wood and others %

4,5

12,9

9,9

6,9

PHYSICAL PRODUCTION OF SOME PRODUCTS

PRODUCTS

1980

1985

1990

1996

Alcohol - 1000 m 3

3676

11563

11518

14134

Sugar - 1000 ton

7844

7995

7451

13507

Cellulose - 1000 ton

3096

3716

4351

6201

A study made about the potential surpluses of self generation in the sugar-alcohol sector (Walter, 1996), based on the present volume of crushed sugar cane (about 284 million of tons) presents the values of 6.4 TWh (vapor turbines of 21 bar in the grinders and 62 bar in the turbo generators) and 25.7 TWh ( VAPOR VIVO of 80 bar and turbines with double extraction and condensation). These data indicate technical potential that do not take into account any economical viability assessment.

The referred surpluses correspond to 0.8 and 3.1 GW of installed capacity, that is, approximately between 1.3 and 5.1% of the present Brazilian installed generation capacity (60.8 GW) and between 23 to 89% of the present installed capacity of the self producers (3.5 GW).

This potential surpluses has been evaluated by some electric power utilities such as Companhia Paulista de Força e Luz - CPFL, in whose distribution area is located most of the sugar and alcohol plants in São Paulo state. The expansion of the cogeneration systems in the CPFL area will add 180 MW from the sugar-alcohol sector until 1999.

In the cellulose sector, according to studies by Carpentieri, 1995, it is estimated a potential surplus of 1 GW in the medium term ( considering the expansion plans of the sector)

TECHNOLOGICAL DEVELOPMENT

ELETROBRAS together with CHEF has been developing the WBP/SIGAME Project, aiming at demonstrating the technical and economical viability of using biomass as a fuel in gasification systems associated with a combined cycle of electricity generation.

The project was started in 1997 and will be extended over 2002 with total
investments of 124.8 million dollars.

GENERAL CHARACTERISTICS OF THE PROJECT
Fuel : Forest biomass
Atmospheric Generation System : low pressure
Installed Capacity : 32 MW
Thermal Efficiency :41%
Specific Consumption:0.98 m 3 solid/MWh
Capacity Factor: > = 80%
Interconnection to the Transmission System : 69 KV