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Biorefineries: a decentralized solution

A project developed at UFRGS seeks way of better using residual products and of ending monocultures
Biorefineries: a decentralized solution

Process of cultivation of microalgae, grown from linseed - Photo: Rochele Zandavalli/UFRGS

By Yuri Correa

In the traditional configuration of refineries, a central facility is surrounded by many hectares of a monoculture that supplies it. Thus, quantity is synonymous with profitability – the more sugarcane plantations around a mill, for example, the better supplied it will be to produce ethanol. Since 2008, the Group of Enhancement, Modelling, Simulation, Control and Optimization of Processes (Gimscop, for its acronym in Portuguese), formed by researchers of the Department of Chemical Engineering of UFRGS, has been working on a new idea that, according to them, is ready to be implemented: the biorefineries. Smaller, decentralized facilities that allow for greater integration with local productions and prevent monopolies.

In order to do so, professors Marcelo Farenzema, Luciane Trierweiler and Jorge Trierweiler devoted themselves in the last few years to researching ways of better using residual biomass of various crops. Trierweiler, for example, focused on sweet potatoes, which are rather produced in Rio Grande do Sul and whose bark can be refined to extract ethanol. This product, in turn, can be used to prepare a Japanese drink called Shochu (the most consumed distillate in Asia), whose Gaucho version Professor Trierweiler calls Tchêchu (playing with the local expression ‘tchê’ and the name of the drink). Linseed, the resulting product of the production of ethanol, can be subjected to a fermentation process that makes microalgae grow – an area that is already being studied by Professor Farenzena. The study of microalgae is interesting because they can be subjected to rapid pyrolysis, that is, the fast heating of biomass that generates residues such as bio-oil and biochar.

In addition to microalgae, rapid pyrolysis is still applied by the group in the rice and eucalyptus bark, which also generates the synthesis gas that is reused to burn other pyrolysis. The substances left over from this process have several usages. Bio-oil, for example, may be employed in the composition of cosmetics, medications, and flavorings. Whereas biochar, a powder-like substance, has favorable structures to be used in soil stabilization, and because of the burning of biomass, its molecules are large and have a high surface area, like hollow structures, forming a kind of empty cocoon inside. Therefore, they can easily apprehend other molecules within themselves, such as water molecules, which makes them great for maintaining soil moisture, as well as toxins, which make them adequate for fluid cleansing applications.

One of the objectives of this project, therefore, is to make the most of the residual waste produced. However, biorefinery is also a project that seeks, in parallel, to go against the monocultures in the traditional scheme of refining. Normally a refinery is centralized; it has an industrial facility around which many hectares of a single crop are planted. In the case of sugarcane, a plantation takes an average of three years to pay off. After the initial investment is made, the first 24 months will be to cover costs, and it is only in the third year that cultivation starts to be profitable. However, the plantation lasts at most five years, because the harvesting begins to deteriorate the seedlings and prevents the planting of generating profit as in the first time. So that the cane grows again, it is necessary to leave in the soil a piece of the main stem of the plant, a seedling that will generate another cane. Harvesters often pull out these new seedlings, but there are also those plants that do not grow back. That is why after a number of times being reused, the plantation needs to start from scratch to yield as much as before. So, in the fifth harvest, it is necessary to restart the planting, which implies an investment similar to the initial one.

Diverging form this approach, biorefineries seek to decentralize production by taking facilities to places where several crops could be harnessed at the same time. In 1997, Gimscop was created with a focus on control area and even though this is still its main function, since 2008, the group began to work on the new project as well. In addition to rapid pyrolysis and the usages of the resulting materials, another of the researchers' focus was the development of optical sensors to supply waste product analyzers. That is, custom, low cost sensors have been created that analyze the refined substances at the facility. This was a vital part of the idea's viability, otherwise all biorefineries would require specialized professionals to operate – which is not the reality. With the sensors, a minimally trained team can already start the production.

None of this, however, has left the labs of the Department of Chemical Engineering yet. Professor Jorge Trierweiler explains that the group has everything ready to put the project into practice (statistics, projections and technology), but still needs partnerships and funding.

Keywords: Biofuels, Biorefineries, Chemical Engineering

Translated by Vitória Coelho Tarouco, under the supervision and translation revision of Professor Elizamari R. Becker (PhD/UFRGS).

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