The Smell of Ethanol Production

After a long bus ride to Brotas, our bus hit a bump and I awoke to see a huge factory surrounded by fields of sugarcane – in my dreamlike state, I immediately drew a comparison to Wizard of Oz. Coming into this alternative energy field trip, I had never seen an ethanol plant and thus had no expectations. Upon arrival to Tonon Bioenergy, we were taken to a room to meet the heads of the various departments– including agriculture and industrial – and to determine the involved processes and sequential steps. There we also learned that Tonon is producing 300,000 liters (L) of ethanol per day and 1200 megawatts hours (MWh) of energy per day. While the plant utilizes 400 MWh of this energy, the excess is sold and the plant has the ability to produce 150,000 L/day more at full capacity. Surprisingly, the plant produced other byproducts beyond ethanol, including biogas and raw sugar. Likely, their exportation of raw sugar to Europe and Asia is a large source of income for the company.

While ethanol production begins with agriculture, we first explored the power plant. The industrial head at Tonon Bioenergy compared the ethanol production process to a winery – something I could wrap my mind around. Despite the smell common to wineries, they reuse the yeast for other fermentation processes and for the purpose of energy production. The ethanol plant had all the characteristics of a factory – the strange smells, loud noise pollution, protective gear, large stacks emitting emissions into the air. This plant broke up its procedures into the following: sugarcane preparation and reception, extraction of the “juice” fro the sugarcane, sugar mill, ethanol distillery, bagging and storage, and electricity generation. The first industrial step in the extraction of the ethanol, removes 70 percent of the “juice”, whereas four more steps and many liters of water are required to get the remaining 30 percent. During this extraction, biogas is produced and turned into steam for electricity generation. The steam from burning unusable parts of the sugarcane in the boilers is used for powering sugar extraction. After this, the juice is sterilized and transported to fermentation tanks, where yeast converts the sugar to make a “wine” that is then taken to distillery towers to remove the ethanol.

Eventually, we left the factory and drove to the sugarcane fields, where the setting dramatically changed, although you could still distinctly see the smoke stacks on top of the hill chugging away. The typical agricultural procedures are required to produce the crop, such as good quality soil, planting, fertilization, harvesting and maintaining the land. While watching the machines cut the sugarcane, straw flew in every direction, eventually settling back on the ground. Since 10 percent of the sugarcane is straw, the plant litter is either burned in the boiler or used to re-fertilize the land. Tonon was notified ahead of time that an environmental science major would be in the group and was eager to answer any questions I might have. Upon speaking with the head of the environmental processes at Tonon, I learned that they let fields regrow for at least five years and sometimes up to 10 years, in order to preserve the viability of the land. Furthermore, they have carbon emission standards they are required to meet and have procedures in place to prevent or address fires. Still, I couldn’t help but notice the clear environmental impacts stemming from the overall process in ethanol production and question how “clean” it was in comparison to wind or solar energy.  

By our third field trip to Tonon Bioenergy, I could easily draw two clear themes from these visits: the role of language (or cultural) barriers and the integrated use of old and new processes in Brazil’s industry. While at CPFL the tour guides struggled at times to explain complex topics in a foreign language, we had translators for our guides at the hydroelectric plant and Tonon. In the latter cases, words were often loss in translation, resulting in the oversimplification of processes by the translator. Additionally, the solar plant at CPFL contained a mix of first generation solar technology and more modern technology. Both the hydroelectric plant and ethanol plant combined manual labor and machinery to produce energy. Although they are in the process of transitioning from manually to mechanically, they are not 100 percent there. These themes have greater implications for the breakdown of Brazil’s energy mix and possibly its industrial sector as a whole. In addition to the abundant resources in Brazil – having high energy potentials in wind, solar and hydropower – the developing country is still experiencing globalization and modernization.