Agricultural energy researchers from the Polytechnic University of Madrid (UPM) have carried out a study, through the use of geographic information systems, to evaluate the potential that the residual biomass of the bananas produced in the province of El Oro, in Ecuador, has for bio-energy applications.
Banana crops are one of the most important crops in the world. During harvest the plant is cut to lower the cluster, making the stem and leaves lignocellulosic waste. Once the cluster reaches the packaging plant another residue is generated: the cluster's rachis. The relationship between waste and product in bananas is 2: 1.
Energy or greenhouse gases
Lignocellulosic residues are left on the ground or taken to open-air landfills. In the first case, they help maintain soil moisture and provide it with organic matter. However, they pose a potential risk of spreading diseases. In both cases, this residues generate greenhouse gases when decomposing. The discarded fruit that has failed to meet quality standards for sale and export is another waste produced in banana crops. The rejection rate may vary between 8% and 20%. This residue is used for animal feed, but most producers prefer to leave it decomposing outdoors due to economic reasons.
The largest exporter of bananas in the world
Considering all this data, a team of researchers from the Polytechnic University of Madrid, led by Professor Maria Dolores Curt, analyzed the case study of Ecuador, as this country is the largest exporter of bananas worldwide (accounting for 29% of global exports). To conduct the study, researchers used geographic information systems; a methodology that is currently widely used for estimating crop production. The sampling and data survey was conducted in the field, in the province of El Oro, to determine the relationship between waste and product; while the biomass' chemical composition and lower heating values were studied in the laboratory.
With this information, researchers determined that Ecuador has 224,137 hectares under cultivation, 59,914 of which are concentrated in the northwestern part of the province of El Oro. Having the crops in one area facilitates the potential location of processing plants. Researches estimated, through secondary information, that it was viable to transport the biomass to a maximum distance of 20 kilometers, which allowed them to determine the area that could be used. They also assumed that 36% of the waste was going to be used for agricultural activities and restricted the amount of biomass that could be used for energy purposes. Finally, researchers chose two potential areas where two plants that generate power from lignocellulosic biomass and produce bioethanol from banana waste could be located.
Eighteen megawatts of electrical power
The study results show that the exploitable potential area amounts to 38,604 hectares, which would generate 190,102 tons of discarded banana (fresh matter) and 198,602 tons of lignocellulosic biomass (dry matter). With these amounts, the plants could potentially produce 19 million liters of bioethanol, and the installed capacity of both the power plants could reach 18 megawatts. According to the researchers, "these plants could cover 55% of the electricity demand in the province of El Oro and 10% of Ecuador's demand for bioethanol. It would also help diversify the country's energy matrix, generate jobs, boost the local economy, and contribute to rural development, which are some of the premises of bio-energy and bio-economy."
Source: Communication Office of the Polytechnic University of Madrid