No 19 - April/May 2000
|ADDITION OF OXYGENATED COMPOUND TO GASOLINE AND THE PROALCOOL EXPERIENCE
Adailson da Silva Santos a,b
Maria Letícia Murta Valle a
Roberto Gomes Giannini a
a Escola de Química/ UFRJ - Rio de Janeiro.
firstname.lastname@example.org English Version
email@example.com Summary: This work has as objective rethinking the present situation of fuels used in the country specially the question of oxygenated compounds that are added to them. For this purpose it is carried out a bibliographic revision and a historical profile of the attempts to use alternative fuels as well as of the policy aiming at reducing fossil fuel consumption by mixing AEAF (anhydrous ethyl alcohol fuel) and other similar ones. Introduction
The use of ethanol as fuel in light vehicles was due to the strategic necessity of reducing the country's dependency on imported petroleum. After the first petroleum crisis the PROALCOOL was created, a very attractive program for sugar cane producers. Due to its structure, PETROBRAS became responsible for alcohol distribution (SANTOS)
Along the years, an extremely complex situation was established involving sugar cane producers, government organs, car assemblers, car component suppliers and PETROBRAS, that raised the point about the efficiency of the adopted model and the impossibility of its continuation.
The confirmation "nod" given by the present President
Fernando Henrique Cardoso to the Agriculture Minister Pratini de Morais will possibly
bring back the PROALCOOL program at the star of the coming millennium. The present article,
which has been partly presented at a Congress in Cuba, is inserted in this restart
From 1931 on the use of AEAF (anhydrous ethyl alcohol fuel) became mandatory for all gasoline commercialized in the country, initially at a proportion of 5% v/v. This percentage has varied along the years due to changes introduced in the energy policy guidelines and also as a function of the sugar and alcohol prices in the external market. Under governmental orientation, this mixture was adopted only when market prices of sugar (external), molasses and alcohol distillate (internal) were below the value expected by the producers. Therefore, alcohol fuel acted as an external market regulator (SILVA SANTOS).
The legislation was changed in 1996 increasing the addition limit from 5 to 10% v/v. Soon after the first petroleum crisis several measures were taken in order to reduce the Brazilian commercial deficit and among the programs proposed at that time was the substitution of gasoline as fuel in light vehicles by a renewable and national source, 3/4 of HEAF (hydrated ethyl alcohol fuel), considered the Brazilian solution for the petroleum crisis (GIANNINI). The National Alcohol Program - PROALCOOL - was established in 1975.
PROALCOOL was implemented with heavy governmental and government-subsided private investments and became a huge success in the seventies and eighties and was boosted by the second petroleum crisis in 1979. The national production increase and the use of alcohol as automotive fuel caused the decrease of petroleum import expenditure in the eighties (SILVA SANTOS).
A sharp decrease in the petroleum international market from US$ 36/bbl (imposed by OPEP between 1979 and 1980) to US$ 15/bbl (in the Rotterdam spot market) at the end of 1985, together with the recovery of sugar prices in the external market [from values below 5 cents/lb in 1985 to values above 15 cents/lb in 1995 (GIANNINI)], have demonstrated that PROALCOOL was not immune to failures and was becoming too expensive to produce surplus. Due to the recovery of sugar prices, ethanol production became less attractive which forced the government to subsidize the producers via PETROBRAS.
In spite of the car fleet increase in 1984-1985, this was not sufficient to consume all the alcohol produced. PETROBRAS started then a research program to evaluate the impact of increasing the AEAF content from 13% to 22% v/v. The last value was not mandatory but only a suggestion of maximum permissible limit. This provoked prompt reaction from the automobile industry represented by ANFAVEA (National Association of Automotive Vehicles Manufactures), that demanded the establishment of a long-term, fixed and constant content so that the vehicles could be optimized for the mixture alcohol-gasoline (MURTA VALLE).
At the end of the eighties the program was violently stricken by the reduction of the sugar cane crop together with the excessive alcohol cars in circulation. This caused a generalized shortage of the product in the country and a large impact on the credibility of the whole program. Naturally the sale of alcohol vehicles was affected and a sharp decrease in the last two years of the decade occurred. Due to this crisis the 22% plateau established at the start of the eighties for the alcohol content was reduced to 13% in 1990 and entirely suppressed in some regions (DAMASCENO). The situation remained confused in what regards the anhydrous alcohol content in gasoline until 1994 when the AEAF content of 22% v/v was again officially fixed according to the demand of vehicle manufactures. The legislation that defined this value was altered in 1997 to 24% v/v of AEAF and to 26% in November 1999 although the present gasoline engines can take 30% alcohol addition (PETROBRAS).
During the nineties the convenience of the model adopted by PROALCOOL was under discussion. The previous limitless fabrication of alcohol cars together with the fact that national production of this fuel could not follow the demand growth (even with the large subsides granted to the sector) made Brazil both the largest producer and the largest importer of ethanol in the world. The program created to decrease the external dependency on fuel became dependent on imports for its maintenance (GIANNINI).
An oscillating offer and a demand affected by constant changes in legislation that controls consumption resulted in the proposition of alternative solutions as for example the use of methanol and ethanol from other sources besides that from sugar cane and the use of oxygenated compounds from petroleum such as MTBE ( methyl ether terc-butyl), ETBE (ethyl ether terc-butyl) and TAME (methyl ether terc-amyl).
Methanol was used as alternative oxygenated fuel in Brazil in the 1989 alcohol crisis. At that time, besides reducing the content of anhydrous alcohol added to gasoline, the DNC (National Fuel Department) suggested the use of a new fuel to be used in vehicles driven by hydrated alcohol. This fuel was denominated MEG (60% v/v of ethanol + 33% v/v of methanol +7%v/v of gasoline). The use o MEG was approved in the city of São Paulo, where the pollution control problems are critical, with the intention of using it in other cities. The program was under pressure (one allegation was that methanol manipulation is dangerous) and it was abandoned even in the city of São Paulo. This program aimed at saving 4 billion liters of ethanol per year.
The importance of this Program for the country is mainly due to factors such as the capacity of reducing 200 thousand bbl of petroleum per day, move a fleet of 4.2 million vehicles and contribute with 16% of the renewable energy matrix of the country besides the possibility of developing a national technology for alcohol-driven cars. Even though there is a growing mechanization in farming, this is the segment that offers more jobs than any other, and it is estimated that there are 1.04 million workers connected to this sector in the Brazilian hinterland.
In this particular, besides helping fixing the less qualified worker in the land, it alters the direction of economic growth vectors, decentralizing the investments from the large urban centers to the hinterland. Good examples of this movement are some cities in the interior of São Paulo, such as Ribeirão Preto and Piracicaba, whose growth is due to not only the sugar-alcohol industry but also to that of citric fruits and soybean (GIANNINI).
In spite of divergence in
opinions, all those involved in the process are unanimous in recognizing that adding
ethanol to fuels was advancement in promoting reduction of emission of sulfur, CO and
particulate by cars, in the first place, and it ratified the substitution of tetraethyl
sulfur in the gasoline (in 1988) as an octane booster due to environmental questions
(MURTA VALLE), in the second place. However, even after two decades, the use of ethanol as
fuel is far from having a defined policy because it taxes all sectors involved (GIANNINI).