Ethanol fuel in Brazil
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In Brazil, ethanol fuel is produced from sugar cane which is a more efficient source of fermentable carbohydrates than corn as well as much easier to grow and process. Brazil has the largest sugarcane crop in the world, which, besides ethanol, also yields sugar, electricity, industrial heating and cachaça. Sugar cane growing requires little labor, and government tax and pricing policies have made ethanol production a very lucrative business for big farms. As a consequence, over the last 25 years sugarcane has become one of the main crops grown in the country.
Ethanol production basics
Sugarcane is harvested manually or mechanically and shipped to a processing plant, which is typically owned and run by big farms or farm consortia and located near the producing fields. There the cane is roller-pressed to extract the juice (garapa), leaving behind a fibrous residue (bagasse). The juice is fermented by yeasts which break down the sucrose into CO2 and ethanol. The resulting "wine" is distilled, yielding hydrated ethanol (5% water by volume) and "fusel oil". The acidic residue of the distillation (vinhoto) is neutralized with lime and sold as fertilizer. The hydrated ethanol may be sold as is (for ethanol cars) or be dehydrated and used as a gasoline additive (for gasohol cars). In either case, the bulk product was sold until 1996 at regulated prices to the state oil company (Petrobras). Today it is no longer regulated.One tonne (1,000 kg) of harvested sugarcane, as shipped to the processing plant, contains about 145 kg of dry fiber (bagasse) and 138 kg of sucrose. Of that, 112 kg can be extracted as sugar, leaving 23 kg in low-valued molasses. If the cane is processed for alcohol, all the sucrose is used, yielding 72 liters of ethanol. Burning the bagasse produces heat for distillation and drying, and (through low-pressure boilers and turbines) about 288 MJ of electricity, of which 180 MJ is used by the plant itself and 108 MJ sold to utilities.
The average cost of production, including farming, transportation and distribution, is US$0.63 per US gallon (US$0.17/L). The alcohol industry, entirely private, has invested heavily in crop improvement and agricultural techniques. As a result, average yearly ethanol yield increased steadily from 300 to 550 m³/km² between 1978 and 2000, or about 3.5% per year.
Electricity from bagasse
Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant; 35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in the fibrous material (bagasse) left over from pressing.
Part of the bagasse is currently burned at the mill to provide heat for distillation and electricity to run the machinery. This allows ethanol plants to be energetically self-sufficient and even sell surplus electricity to utilities; current production is 600 MW for self-use and 100 MW for sale. This secondary activity is expected to boom now that utilities have been convinced to pay fair price (about US$10/GJ or US$0.036/kWh) for 10 year contracts. The energy is especially valuable to utilities because it is produced mainly in the dry season when hydroelectric dams are running low. Estimates of potential power generation from bagasse range from 1,000 to 9,000 MW, depending on technology. Higher estimates assume gasification of biomass, replacement of current low-pressure steam boilers and turbines by high-pressure ones, and use of harvest trash currently left behind in the fields. For comparison, Brazil's Angra I nuclear plant generates 600 MW (and it is often off line).
Presently, it is economically viable to extract about 288 MJ of electricity from the residues of one tonne of sugarcane, of which about 180 MJ are used in the plant itself. Thus a medium-size distillery processing 1 million tonnes of sugarcane per year could sell about 5 MW of surplus electricity. At current prices, it would earn US$ 18 million from sugar and ethanol sales, and about US$ 1 million from surplus electricity sales. With advanced boiler and turbine technology, the electricity yield could be increased to 648 MJ per tonne of sugarcane, but current electricity prices do not justify the necessary investment. (According to one report, the World bank would only finance investments in bagasse power generation if the price were at least US$19/GJ or US$0.068/kWh.)
Bagasse burning is environmentally friendly compared to other fuels like oil and coal. Its ash content is only 2.5% (against 30-50% of coal), and it contains no sulfur. Since it burns at relatively low temperatures, it produces little nitrous oxides. Moreover, bagasse is being sold for use as a fuel (replacing heavy fuel oil) in various industries, including citrus juice concentrate, vegetable oil, ceramics, and tyre recycling. The state of São Paulo alone used 2 million tonnes, saving about US$ 35 million in fuel oil imports.
Program statistics
Except where noted, the following data apply to the 2003/2004 season.
| land use: | 45,000 km² in 2000 |
| labour: | 1 million jobs (50% farming, 50% processing) |
| sugarcane: | 344 million metric tonnes (50% sugar, 50% alcohol) |
| sugar: | 23 million tonnes (30% is exported) |
| ethanol: | 14 million m³ (7.5 anhydrous, 6.5 hydrated; 2.4% is exported) |
| dry bagasse: | 50 million tonnes |
| electricity: | 1350 MW (1200 for self use, 150 sold to utilities) in 2001 |
The labour figures are industry estimates, and do not take into account the loss of jobs due to replacement of other crops by sugarcane
Effect on oil consumption
Most cars in Brazil run either on alcohol or on gasohol; only recently dual-fuel ("Flex Fuel") engines have become available. Most gas stations sell both fuels. The market share of the two car types has varied a lot over the last decades, in response to fuel price changes. Ethanol-only cars were sold in Brazil in significant numbers between 1980 and 1995; between 1983 and 1988, they accounted for over 90% of the sales. 80% of the cars produced in Brazil in 2005 were dual-fuel, comparing to only 17% in 2004.Ethanol-fuelled small planes for farm use have been developed by giant Embraer and by a small Brazilian firm (Aeroálcool), and are currently undergoing certification.
Domestic demand for alcohol grew between 1982 and 1998 from 11,000 to 33,000 cubic metres per day, and has remained roughly constant since then. In 1989 more than 90% of the production was used by ethanol-only cars; today that has reduced to about 40%, the remaining 60% being used with gasoline in gasohol-only cars. Both the total consumption of ethanol and the ethanol/gasohol ratio are expected to increase again with deployment of dual-fuel cars.
Presently the use of ethanol as fuel by Brazilian cars - as pure ethanol and in gasohol - replaces gasoline at the rate of about 27,000 cubic metres per day, or about 40% of the fuel that would be needed to run the fleet on gasoline alone. However, the effect on the country's oil consumption was much smaller than that. Although Brazil is a major oil producer and now exports gasoline (19,000 m³/day), it still must import oil because of internal demand for other oil byproducts, chiefly diesel fuel (which cannot be easily replaced by ethanol).
Environmental effects
The improvement in air quality in big cities in the 1980s, following the widespread use of ethanol as car fuel, was widely evident; as was the degradation that followed the partial return to gasoline in the 1990s.However, the ethanol program also brought a host of environmental and social problems of its own. Sugarcane fields were traditionally burned just before harvest, in order to remove the leaves and kill snakes. Therefore, in sugarcane-growing parts of the country, the smoke from burning fields turns the sky gray throughout the harvesting season. As winds carry the smoke into nearby towns, air pollution goes critical and respiratory problems soar. Thus, the air pollution which was removed from big cities was merely transferred to the rural areas (and multiplied). This practice has been decreasing of late, due to pressure from the public and health authorities. In Brazil, a recent law has been created in order to ban the burning of sugarcane fields, and machines will be used to harvest the cane instead of people. This not only solves the problem of pollution from burning fields, but such machines have a higher productivity than people.
Many nations have produced alcohol fuel with no destruction to the environment. Advancements in fertilizers and natural pesticides have eliminated the need to burn fields. With condensed agriculture, like hydroponics and greenhouses, less land is used to grow more crops.
Social implications
The ethanol program also led to widespread replacement of small farms and varied agriculture by vast seas of sugarcane monoculture. This led to a decrease in biodiversity and further shrinkage of the residual native forests (not only from deforestation but also through fires caused by the burning of adjoining fields). The replacement of food crops by the more lucrative sugarcane has also led to a sharp increase in food prices over the last decade.Since sugarcane only requires hand labor at harvest time, this shift also created a large population of destitute migrant workers who can only find temporary employment as cane cutters (at about US$3 to 5 per day) for one or two months every year. This huge social problem has contributed to political unrest and violence in rural areas, which are now plagued by recurrent farm invasions, vandalism, armed confrontations, and assassinations.
Some question the viabiliy of biofuels like ethanol as total replacements for gasoline/crude oil. One concern is that sugarcane cultivation will displace other crops, thus causing food shortages. However, these concerns seem to be groundless despite having the world's largest sugarcane crop, the 45,000 km² Brazil currently utilizes for sugarcane production amount to only about one-half of one percent of its total land area of some 8.5 million km². In addition, the country has more unused potential cropland than any other nation. Some authors, like George Monbiot, fear that the marketplace will convert crops to fuel for the rich, while the poor starve and biofuels cause environmental problems. It is unclear how this would be different from the current situation, as most food crops are grown and exported to richer nations. In any, case the cultivation of sugarcane for energy production is only likely to increase as fossil fuels become increasingly scarce and more expensive.
Exports of Brazilian ethanol
On 19 December 2005, the government-based Petrobras announced a contract with the Japanese Nippon Alcohol Hanbai for the creation of a joint-venture based in Japan to import ethanol from Brazil. The company, Brazil-Japan Ethanol, will have as its main object the creation of an ethanol market in Japan.The U.S., potentially the largest market for the Brazilian ethanol, currently imposes a trade restrictions on the product in order to encourage domestic production of corn ethanol, which is, however, much less efficient than its sugarcane counterpart.
External links
- [Cogeneration in Ethanol Plants by P. M. Nastari]
- [CDM Potential in Brazil, by S. Meyers, J. Sathaye et al.]
- [UNICA - Brazilian Sugarcane growers assoc.] (in Portuguese) and its [machine translation]
- [BBC News video segment on ethanol in Brazil]
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