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Agronomy industry

Environmental and energy gains

Innovative project of mini mills proposes total integration around alcohol production

A daring project, founded on the concept of agronomy industry integration, could transform sugarcane alcohol into a definite substitute for imported petroleum, used for refining into gasoline and diesel fuels. This is the expectation of professors Geraldo Lombardi and Romeu Corsini, of the Engineering School of São Carlos (EESC) of the University of São Paulo (USP), responsible for the conception of a network of Integrated Alcohol Mini Mills, named as Muai.

As yet unprecedented in Brazil and in the world, these mini mills are establishments of medium size that have as their primary goal the production of fuel alcohol. The Muai units will be using already proven technology, along with regeneration and recycling processes. They are being projected to produce alcohol, horticulture products, dry yeast used in animal feed, electrical energy, as well as leaving space for the rearing of cattle. “The Muai project is much more than a simple reduction of scale of a large sugar-alcohol mill”, explains Romeu Corsini, retired professor of the Transport Department of the EESC and co-author of the project. “The big innovation is in the concept of total integration, up until now not adopted by any company in this area.”

According to the researcher, the mini mill must produce 40,000 liters of alcohol per day in order to be competitive with oil fuels. Planned to operate on land of 4,310 hectares, the Muai project will generate one hundred and thirty one permanent jobs, 25% of those hired out to third parties. The traditional sugarcane agriculture is associated with the growing of saccharine sorghum, a plant with almost three meters in height and of the same family as the grasses, which contains sweet and succulent culm (stalk). With this plant it will be possible to raise to ten of the twelve months of the year, the time of the working of the mini mill, as against the eight months conventionally established.

In the Muai project 3,630 tons per year of agricultural products related to sorghum will be produced. The sugarcane and sorghum culms produce the juice and the bagasse. From the fermented juice 1,130 tons per year of dehydrated yeast will be produced, and by way of the distillery, alcohol and the liquid residue. The biodegraded liquid residue transforms itself into bio-fertilizer and biogas. In the 188 hectares destined towards cattle raising, there will be reared 2,800 head of cattle in a semi-confined regime, seven months in the corral and five months outside of it, fed by the tips of the sugarcane and the sorghum with other protein additives added to it.

The bagasse, 40% of the dry straw and the biogas (natural gas produced between crops) are burned in a furnace for the production of superheated steam at 450°C. The vapor runs a turbo-generator of high potential and efficiency, which produces 6.36 megawatts (MW) of surplus electrical energy at a cost of US$ 6.58 per megawatt/hour, which will make up the second source of income of the Muai project. “The project privileges the maximum thermodynamic efficiency, productivity, the environment and social within the concept of self-sufficiency”, explains the aeronautical engineer Geraldo Lombardi, professor at the Hydraulics and Sanitation Department of EESC.

Network of mills
In order to prove the economic viability of the Muai project, Lombardi and Corsini promoted, with the financial support of FAPESP, the visit of professor Pedro Antonio Rodríguez Ramos, of the José Antonio Echevaría Upper Polytechnic Institute of Havana, Cuba, for the period of one year. Ramos concluded, in November last, the project Economic Evaluation of an Integrated Alcohol Mini Mill. It concluded that, to make possible the substitution of 600,000 barrels of crude oil imported daily by Brazil, it would be necessary to install 3,870 Muai projects in the country.

Together they would produce 155 million liters of alcohol per day, a thermal potential equivalent to that of the imported petroleum, and would make available 24,600 MW of surplus electricity, the equivalent of a little less than two hydroelectric dams the size of Itaipu. The studies also demonstrated that the investment, estimated at US$ 12.1 million, would present a return period of 6.9 years, the same as that of a conventional mill that produces exclusively 200,000 liters of alcohol per day.Besides all of the economic and social advantages, such as the generation of 507,000 fixed jobs, the annual savings f US$ 5.5 billion on the importing of crude oil and the generation of US$ 5.8 billion in taxes per year, the Muai project has unparalleled environmental benefits.

The mini mill attends to the requirements of the Kyoto Protocol with respect to the emission of gases. “By substituting oil derivatives, it would avoid the cumulative emission of almost 2 million tons of carbon dioxide per day, a gas that adds to the greenhouse effect and to the quality of life on the Earth. It would further remove from the atmosphere 197 million tons of carbon dioxide (CO2) through the continuous growing of sugarcane”, explains Lombardi. And to finish, 680 hectares of the land for each Muai project, corresponding to 20% of the agricultural area, would be destined to forestry reserves, attending to the legal regulations of preservation.

How it would work
In function of its multiple activities, the flowchart of the Muai project is complex. Nevertheless, the thinking behind the mini mill is simple: everything must be reprocesses and recycled. For example, the sugarcane straw is used in the protection of the soil against damaging weeds, as well as being destined to the production of steam to generate electricity. The liquid residue and the animal droppings transform themselves into biogas for burning in the furnaces and also into biofertilizers for use on the canebrake.

The fact that it is anchored into a complete cycle of energy and agronomy industry production confers to the project good prospects for its implementation. Sugarcane producers have sought out the two researchers in order to obtain more details. Cuba would also benefit from the concept of the total integration in production. Professor Ramos has returned to his country, severely dependent on the importation of petroleum, with the promise compromise of presenting the Muai project to the Cuban government.

The project
Visit of Professor Pedro Antonio Rodríguez Ramos, of the José Antonio Echevaría Upper Polytechnic Institute , for the Economic Evaluation of an Integrated Alcohol Mini Mill; Modality Visitor research assistance; Coordinator Geraldo Lombardi – Engineering School of São Carlos – USP; Investment R$ 56,181.60