Ethanol Plant

Today, we visited Tono, an ethanol plant located about 3 hours from the city of Sao Paulo. We were received by a group of employees of the plant, who were going to give us a tour of the plant. They offered us breakfast, which was really nice, considering that we had to leave at 6:30 am to get to the plant and got a very light breakfast. They continued to explain the process to get ethanol out of sugar cane, and produce biomass energy.

First, they harvest and collect the sugar cane. They use machinery for harvesting most of the crops, but there are some places that cannot be accessed by the trucks and have to be harvested manually. The cane is carried into the plant and goes through the extraction process. In this step, the cane is shredded with blades and the juice is extracted from it. The cane goes through this process 5 times. 70% of the juice is extracted in the first station, and then water is added in the other 4 stations to extract the remaining 30%. The water consumption is very high, they need 230% of the amount of cane that they have. However, it can be reused, and they recycle water from other processes.

The solid residues of the process are called bagasse, which is then used to fuel boilers and generate energy, making the plant self sustainable. The juice is then taken through the evaporation process to take the water out and get a concentrated syrup called Molasses. They are able to capture the water through condensation and use it in other processes, such as irritation for the crops or adding it in the extraction stage. The Molasses is then further processed and some sugar crystals are created, which are then separated from the syrup through centrifugal. This is the process for making raw sugar, which they can sell to be processed into white fine sugar.

The molasses then goes through a fermentation process by adding yeast. This process is very similar to the fermentation of different alcoholic beverages such as wine, beer and cachaça. The difference is that for making ethanol, the yeast can be reduced, and the final product has a higher percentage of alcohol. It is then distilled to get ethanol.

They took us to the lab where they simulate the process in a smaller scale. Samples are taken to estimate how much ethanol they will produce and to make sure that there isn't anything wrong in any step of the process. They showed us a sample of ethanol with 93.8% pure, and we saw yeast in a microscope.

After that, we had lunch in the company's dinner and when we finished eating, went to a sugarcane plantation. We saw the special trucks used to cut the sugar cane, and our professor got to drive it. It has an arm with blades to take the leaves at the top of the cane and then uses some cylinders to get the cane which is cut with blades and thrown into a truck driving beside it. The residues of the leaves are on the ground and have to be cleaned up to prevent fires from occurring. They also clean the blades of the trucks every 3 hours and add water to prevent fires. Every truck has a fire extinguisher and there are water tanks nearby. We thanked our tour guides and translators for everything and headed back. This was another trip where I learned a lot.

The plant produces 1200 MWh per day and 300,000 liters of ethanol per day. There is very few waste in the process and the plant is pretty much self sustainable. However, it still has many issues. Big areas of nature have to be cut down to plant sugar cane. Besides hurting the environment, it takes a lot of space and all that land could be used for something else. The process is not too safe, since fires are quite common and when we got to the plant, there was a board that counted the days since the last accident in the different areas, and for some departments, the numbers weren't too high. Also, the plant had big chimneys, and looked like there was CO2 emission. Which makes me wonder if the production of ethanol damages the environment in some scale. There is still a lot of room to improve the processes of alternative energy.