Machine will help extract light from straw
Oscar Braunbeck coordinates energy generation project from
of sugarcane straw wasted in the fire

JOÃO MAURÍCIO DA ROSA

DIt should work like a shaver, scraping the surface without moving away from it or disturbing the soil. It also cannot be sophisticated, just a machine that is sufficiently robust and efficiently constructed from welded steel. Equipped with conventional transmissions that are easy to adjust and maintain, its price and performance make it competitive in the market. Therefore, certain electronic, hydraulic or laser cutting resources, no way.

This is the principle of the sugarcane harvester that is being developed by Unicamp's Faculty of Agricultural Engineering (Feagri) and which could enable the use of yet another source of biomass for energy production: sugarcane straw.

Initially designed to reduce harvesting costs and improve sugarcane quality, the machine gained a new dimension in light of the energy crisis in the country due to its potential for approximately 30 million tons/year of straw, which are currently burned outdoors.

“Bagasse has been the only residue used from sugarcane biomass, mainly because it is available spontaneously next to the industry’s boiler. To date, very little has been said about the use of straw, but there should be an appreciation of the energy embedded in straw in light of the current shortage crisis”, explains Professor Oscar Antonio Braunbeck, coordinator of the Agricultural Machinery Projects Laboratory at Feagri.

In fact, straw has only brought inconvenience to sugarcane producers and cutters. The former are targeted by a state law in São Paulo, which limits the traditional and harmful burning of sugarcane fields to facilitate cutting. The workers, because without burning the straw, cannot see the straw into which they stick the scythe and still run the risk of facing venomous animals – and losing jobs to the machines.

“The only way to cut sugarcane manually is to burn it. However, the law requires that a large part of the harvest areas be harvested without prior burning, which few obey, even subjecting themselves to fines. They do not comply because they cannot find a suitable harvesting technology; the known ones impose high investment and losses and low quality”, explains Braunbeck.
With a concept developed in Australia in the 50s, current harvesters used in sugarcane fields have another drawback. In addition to the loss of up to 15% of the raw material harvested, these machines drag along around 5 kilos of earth per ton of sugarcane”, recalls the researcher. And this land goes with the sugarcane for milling, compromising its quality. In the case of straw, contamination with soil exceeds 10 kg/t, which makes it unfeasible to burn it to produce energy.

Own technology – Having worked for eight years in the sugar and alcohol sector in the 80s, Braunbeck realized that Brazil needed its own technology for mechanical harvesting. “Australia conceived this technology 50 years ago, in a state of urgency, as it did not have the labor force to harvest. He didn’t think about other markets when he executed the project,” he explains.

For this reason, the professor decided to develop the national machine within Feagri's postgraduate program and the project was financed in several phases by Fapesp (Fundação de Amparo a Pesquisa do Estado de São Paulo). Today it is being carried out with the help of four scholarship students. “It’s a simple project, structured in three points: cutting the base, the pointer and the leaves. All this without harming the stem, where there is more sugar concentration; without damaging the ratoon to prevent the entry of pests or diseases; and without dragging earth, improving the quality of the raw material and protecting the longevity of the sugarcane field”, he details.

The project has been developed for four years, in partnership with a machining industry in Piracicaba. The prototype would be completed within three or four years, according to forecasts, but the worsening energy crisis led the team to incorporate a straw baling process into the harvester. “Now we cannot specify when the prototype will be consolidated as a commercial product”, he states.

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The industry doesn't move

Since the Unicamp prototype is the only technological research involving alternative principles for sugarcane harvesting underway in the country, what do Brazilian agromechanical industries do? The answer is little or nothing, as there is not a sufficiently attractive market. Braunbeck says that to meet the demand of all sugarcane fields in Brazil, the largest producer in the world, the factories would have to maintain around three or four thousand machines on the market. “The quantity is considered insufficient to justify investment in basic research and product development, if we consider that there are currently four manufacturers,” he says.

To give a better idea, the professor recalls that up to the current stage of work, Unicamp has not spent more than R$300 of the funds raised from various sources, in four years. The value of the survey must be equivalent to the maximum price of a machine already with a tractor. “A similar development, hypothetically carried out by the industry, using more physical and less analytical resources, would cost four machines”, he compares. Currently, an Australian model harvester is worth around R$450.

The lower initial price and higher yield of the machine promise to halve the cost of harvesting. Losses should fall by half, from 10% to 5%, with the same potential for reducing land dragged per ton harvested.

The greater yield (tons/day) of the proposed harvester arises fundamentally from the elimination of the logistics necessary to maintain synchrony between harvesting and transportation. “Conventional harvesters have to travel alongside a truck to launch the sugarcane that is harvested and cut into wheels. Our harvester cuts the entire stalks and deposits them in high-density windrows for later loading and transportation, thus separating harvesting and transportation operations.”

The time to complete the project, according to the researcher, must respect the University's priorities, which are undergraduate and postgraduate education. “The industry is in a hurry. It is certain that once it is ready and running, there will be people interested in transforming this research into a market product”, believes Braunbeck.
For the professor, burning will only be eradicated from Brazilian sugarcane fields when technology exists that makes harvesting with or without burning indifferent, in terms of cost and quality of the harvested product. “While crops such as wheat, corn and other grains have been fully mechanized for more than half a century, sugarcane, which offers the highest mass production per hectare, is still in its infancy and without viable technology,” he argues.

Therefore, he highlights two key factors in Unicamp's work to get the country out of this delay: the commitment of students and Fapesp's resources. “Resources are few, but sufficient. You don't need loads of money to research. The important thing is that we have a serious structure, so that the money always comes and the research continues”, he concludes.