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| Fig. 1: Explanation of the Bioethanol Process. Source: EERE (Courtesy of the U.S. Department of Energy) |
In Brazil, sugar canes have been grown for 500 years, and such a country can be considered by far the world's biggest exporter of it. However, sugar to today's economy is not only used for its edible sub products, nowadays, it also forms a renewable-energy complex. Biofuels, which are mainly derived from sugar, are Brazil's most meaningful source of energy after oil. For a unit of energy, the production and use of sugar-based ethanol generates only two-fifths of the carbon emissions of petrol, and half those of corn-based ethanol, according to the United States Environmental Protection Agency. Furthermore, bioplastics made from sugar cane are poised to move from the laboratory to the corner store, with the launch of soft-drink bottles. [1] Thus, one can understand the importance of sugar's ethanol - throughout Brazil's history. However, is that energy sustainable? That is, can Brazil actually have most of its energy generated by the extraction of ethanol from sugar canes? Before one can answer it is important to first delve into what is bioethanol and how one obtains it.
Bioethanol is an alcohol made by fermenting the sugar components of biomass. Nowadays, it is made mostly from sugar and starch crops. Due to advanced technology being developed by the Biomass Program, cellulosic biomass, like trees and grasses, are also used as an fuel for cars in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol production is highly associated with fermentation - a series of chemical reactions that convert sugars to ethanol. The fermentation reaction is caused by yeast or bacteria, which feed on the sugars. Ethanol and carbon dioxide are produced as the sugar is consumed. The simplified fermentation reaction equation for the 6-carbon sugar, glucose, is:
The basic processes for converting sugar and starch crops are well-known and widely used commercially today. While these types of plants generally have a greater value as food sources than as fuel sources there are some exceptions to this. For example, Brazil uses its huge crops of sugar cane to produce fuel for its transportation needs. [2] Now, we shall analyze the advantages and disadvantages of ethanol use as a source of energy.
The advantages of ethanol use for energy production in Brazil are diverse. The most important and widespread by the media is definitely the reduction of emissions: environmental officials estimate the use of sugarcane ethanol in Brazil has reduced the country's greenhouse gas emissions by 600 million metric tons of carbon dioxide since 1975. Furthermore, one can also take into account the prospective economic growth that Brazil can have due this source of energy: economists estimate that Brazil's total economic output is 35% higher today than it would be had it been without the country's focus on diverse energy production from offshore oil to sugarcane ethanol production.
Even though sugar cane production is concentrated mainly in two geographic regions of Brazil, the Northeast and the Southeast, dramatic land use changes have been evident in both those regions since the establishment of Proalcool - which can be described as a program that stimulates the production of alcohol as an energy source in Brazil. Less than 1% of Brazil's total territory would be needed to reach production of 30 billion liters of alcohol per year. Nevertheless, the area in which sugar cane production is most concentrated has been subjected to the negative effects of a large monoculture crop. A monoculture is the growing of only one species of crop, grown densely over a large land area. As such, monocultures require increased use of pesticides, since the area would be an ideal location for crop pests and diseases to grow. Furthermore, it requires vast areas of land, and therefore can lead to the destruction of natural habitats. By allowing very fertile agriculture production areas, such as Sao Paulo, to be devoted to sugar cane necessarily drove other crops out of the area, driving up the price of traditional food crops. Thus, not only are traditional food crops forced to move to other areas, the price of land surrounding sugar cane plantations has seen a dramatic increase since the creation of Proalcool. Furthermore, the practice of subsidizing one primary crop for ethanol production, especially a crop that is dominated by a relatively few large-scale farmers, implies the denial of similar subsidies to other crops or producers. [3]
As one can see there are many advantages and disadvantages to the use of ethanol as an energy source. Thus, one might wonder what is the political and economical take on the subject. As described before Proalcool (Programa Nacional do Alcool) was created in 1973 at a time of great flux in the international sugar industry. The oil crisis of 1973 had sent gasoline prices soaring internationally and the Brazilian government decided to look to possible domestic sources of fuel production in order to insulate itself from the chaotic market. The program was aimed at bolstering Brazil's national sugar economy by safeguarding the privately owned sugar industry. The Proalcool mandate was simple enough to implement as alcohol plants already in operation required only simple modifications to produce ethanol. Proalcool's specific mandate was to produce 3.5 billion liters of ethanol from sugar cane by 1980. For comparisons sake: in the year before Proalcool was initiated, 1974, the nation had 130 ethanol distilleries, which produced 625 million liters of ethanol from sugar cane. [4] In the first years after the creation of Proalcool, sugar prices were stabilized as many existing sugar plants expanded or constructed alcohol fermentation and distillation processes, turning millions of tons of surplus sugar into ethanol. Even though at the inception of Proalcool the Brazilian sugar industry was the largest in the world, the continued mandate to increase production of ethanol required substantial subsidies for farmers and producers. However, nowadays with the prospect of large amount the of oil in the Brazilian pre-salt layer that would eventually raise Brazil's oil stock to the greatest in the world, the excitement regarding ethanol based energy has substantially decreased. Furthermore, due production shortfalls Brazil has had to import unprecedented volumes of the biofuel. The country reportedly imported an estimated 80 to 200 million liters (21.1 to 52.9 million gallons) of ethanol during the first quarter of 2011. [5]
Thus, given its environmental benefits, sugar-based ethanol has the potential to be a global industry. But while Brazil exports 70% of its sugar production, 75% of its ethanol output is still sold at home. That can be explained mainly because the United States and Europe see ethanol as an agricultural commodity and protect their own producers (mainly of corn ethanol). Furthermore, the world market for Brazilian ethanol will grow and that the sugar industry can triple its electricity co-generation capacity to 15,000MW (around 27% of Brazil's demand today) from its present acreage of cane. [1] However, due to more economically viable and stable forms of energy, sugar canes have not such a sweet perspective as a form of energy in the foreseeable future.
© Cibele Montez Halasz. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Energy in Brazil: Ethanol's Mid-life Crisis," The Economist, 2 Sep 10.
[2] R. B. Gupta and A. Demirbas, Gasoline, Diesel, and Ethanol Biofuels From Grasses and Plants (Cambridge, 2010).
[3] M. Roehr, The Biotechnology of Ethanol: Classical and Future Applications (Wiley-VCH, 2001).
[4] I. Almeida and T. C. Dreibus, "Brazil to Become Net Importer of U.S. Ethanol, Czarnikow Says," Bloomberg Businessweek, 22 Nov 11.
[5] Reuters, Da, "Brasil Vai Importar 1 Bi de Litros de Etanol, Diz Associação," Folha de São Paulo, 12 Sep 11.