For a more sustainable future

Publicado em 05/07/2018
Revista Diálogo Brasil – Alemanha (p. 46)

During the opening speeches of the 6th German-Brazilian dialogue on Science, Research, and Innovation, USP Professor Emeritus and President of Fapesp José Goldemberg stated that biomass has the potential for increasing its share as a worldwide energy source from its current 10% to 25% or 30%. Judging by the research of Mário T. Murakami, from the Brazilian Bioethanol Science and Technology Laboratory (CTBE), and of Jürgen Kern, from the Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), the prediction could be close to being fulfilled.

On the second day of the event, during a panel discussion moderated by Marie Anne van Sluys, Coordinator of Fapesp’s research program in Bioenergy and teacher at Institute of Biosciences of São Paulo University, Murakami opened the session on Biomass and Biorefinery Technologies by dealing with technologies and biological routes for producing advanced biofuels. He is a specialist in applied glycobiology and glycoscience and focused his presentation on emerging technologies, such as improving enzymes by applying biotechnology, as well as producing second-generation bioethanol (or cellulosic ethanol), is an energy source that can be obtained from sugarcane bagasse or straw, sorghum, corn, beets, etc.

2G bioethanol is seen as an alternative for expanding alcohol production in Brazil, without the need to increase planting and based on an abundant raw material: sugarcane straw and bagasse. The researcher explained that there are four main steps for producing second-generation ethanol: separating the raw material, pretreating it, performing enzymatic hydrolysis, and fermenting. “During the manufacturing process of cellulosic ethanol, the waste is pretreated, where the fibers are destructured and then it is transformed into soluble sugars via a process called enzymatic hydrolysis. This process, however, is handled by very few companies.”

One of the objectives of Murakami’s team is to develop enzymes that can improve this process in Brazil. “We have to increase the efficiency of the hydrolysis and reduce the cost of the enzyme,” he says. According to him, the objective is to create “tailor-made” enzymes for Brazilian biomass. “We developed the Enzyme Cocktail Program.

One of the missions of this program is to create a customized cocktail of enzymes for Brazilian biomass. Our country has mastered most of the technology for producing second-generation bioethanol, including industrial yeasts and a consolidated pretreatment process. The development of a Brazilian technology for producing enzymes will ensure that the country is technically autonomous along the entire production chain of 2G bioethanol.”

According to Murakami, the enzyme developed by his group, named CTBE X01, performs well, but still has not achieved good productivity goals. He explains that one of the challenges for producing new enzymes is that scientists still have a very limited understanding of nature’s repertoire for degrading biomass. “There is much to be learned about the architecture of plant cell walls,” he acknowledged. Other technologies developed in the CTBE and mentioned by Murakami were second-generation N-Butanol, enzymatic biodiesel, and biokerosene.

Biochar and lactic acid – Jürgen Kern’s group is investigating the material and energy uses of several types of biomass. “We study the entire biomass productive chain, from the harvest process to its fermentative conversion into biogas and lactic acid. We are especially interested in three different techniques for applying biomass: lactic acid, biogas, and “biochar”, which is formed from the words ‘biomass’ plus ‘charcoal’.”

According to Kern, the group’s objective is to develop technologies for providing valuable materials from a biological and fuel base, to be used sequentially like a cascade.

“For example: the leftovers from the process of producing biogas can go through a thermal trans-formation into biochar, which can finally be used as a fertilizer for farm crops and for other purposes,” he said. According to Kern’s assessment, this type of resource management is a way of closing the nutrient cycle – and it is a potential strategy for mitigating CO2 emissions. Kern presented the concept of integrated biorefineries, divided according to the input of biomass and the final product generated.

Plants that contain starch generate lactic acid for the chemical industry. Fibrous plants provide raw materials for the materials industry (the fibers) and biochar (from residues). Lignocelluosic plants generate raw materials for obtaining both biogas and biochar.

Little or nothing is wasted in the integrated biorefineries. For example, they can absorb residues in a reactor for producing not only biogas, but also a compound that, in turn, can be used as the basis for producing biochar. And this can be used in different ways in agriculture, to improve soil quality.

“Some input and output paths are already established. In the case of lactic acid, for example, production is carried out via grains or plant residues that contain starch. We are investigating the long-term stability of the fermentation processes, the selection and use of new bacteria that produce lactic acid, and other types of raw materials.”

In the case of biogas, the studies focus on developing reactors for both optimizing the conversion of solid biomass and the production of biogas from partially solid biomass, molecular markers for detecting relevant micro-organisms for these processes, and other subjects of great importance.

As for biochar, the group has been characterizing different types of charcoal from the physio-chemical perspective, with a special focus on stability. It also works on the interaction between the types of charcoal and the micro-organisms in the soil and the effects of biochar as a fertilizer. Finally, it evaluates the process of obtaining biochar in terms of function, performance, costs, and environmental impact. According to Kern, among advantages of using this material are the use of residues from the thermal-chemical conversion process, the improvement of degraded and poor soils, the improvement of water storage, and an increase in crop productivity.