This is one of the initiatives of a new laboratory that will develop
electrolytic reactors focusing on Brazil’s specific needs
Vinasse is a polluting waste resulting from the production of ethanol. It is generally used as fertilizer in crop fertigation, especially of sugarcane, because it is rich in potassium. “Transporting this waste material to the planted fields is an expensive and laborious process for the mills. Not to mention that if it is incorrectly distributed, the vinasse can damage the crop and the soil, as well as leak into the water table. It is possible to improve this process,” says Thiago Lopes, Professor in the Polytechnic School of the University of São Paulo (Poli-USP).
As the head of the new Cells and Fuel Laboratory, located in Poli-USP and within the programs of the Research Centre for Greenhouse Gas Innovation (RCGI), funded by Shell of Brazil and by the São Paulo Research Foundation (FAPESP), Lopes intends use the lab to develop an electrolytic reactor focusing on the special needs of the nation’s sugar and alcohol industry. “The composition of vinasse is 95% water. The goal is that through the application of this reactor we will be able to breakdown the water molecules and generate oxygen and green hydrogen,” he explains.
When widely applied, green hydrogen can be used, for example, in the production of ammonia that goes into the composition of fertilizers. “Today, ammonia is synthesized with hydrogen from natural gas, which generates a CO2 footprint,” says Lopes. But, on the other hand, pure oxygen can be used for the combustion of sugarcane vinasse. “By condensing water, pure CO2 can easily and economically be obtained either for storage or for conversion into products.”
One of those products is oxalic acid, a chemical that, together with a biomonomer, will go into the composition of the hydrogel under development by the Hydrogel Program, which is funded by Shell of Brazil with resources from the R&D Investment Clause of the Concession Contracts of the National Oil, Natural Gas and Biofuels Agency (ANP). The Hydrogel Program involves several USP research institutions under the leadership of the RCGI, as well as the Federal University of Rio Grande do Sul (UFRGS).
In this case, oxalic acid will be produced by the Fuel Cell Laboratory, in collaboration with the Institute for Energy and Nuclear Research (IPEN) and the Brazilian Agricultural Research Corporation (EMBRAPA). The hydrogel resulting from the entire research process will be applied in the form of granules, during planting, which will degrade and release carbon to be stored in the soil. “We plan to create a virtuous cycle and raise up new markets in the national sugar and alcohol sector.”
Another advantage of the reactor is that it makes the vinasse more concentrated – where for every liter of ethanal about 10 liters of vinasse are produced. “This is an enormous volume to be stored and transported. If it is more concentrated, free of a fraction of its water, the bagasse will take up less space and require less transportation. I should mention that the transportation is usually performed by diesel-powered trucks, which adds CO2 footprints to Brazilian ethanol,” Lopes points out.
According to Lopes, the concentrated bagasse would also minimize the addition of synthetic fertilizer to the crop. “The mixture of vinasse and synthetic fertilizer causes greater CO2 emissions. Not to mention that by reducing the volume of water we prevent excess liquid from reaching the water table and polluting rivers.”
Green hydrogen can also power vehicles having a fuel cell engine, which is one of the types of all-electric vehicles now circulating on the world’s highways, especially in Japan. The other mode is electric vehicles powered by rechargeable batteries via special hookup points. “In the engine of a fuel cell vehicle, hydrogen reacts with oxygen that comes from the environment. The electrical energy that is released powers the vehicle and the process leaves only heat and pure water as residues. Currently, this hydrogen is obtained worldwide from natural gas, which leaves CO2 footprints. Thus arises the importance of finding ways to produce green hydrogen. This is what we intend to do in the laboratory with the electrolytic vinasse concentrator. Everything is interconnected,” Lopes explains.
The researcher estimates that by 2040 the production of this type of vehicle will take off in Brazil. He states that “this will likely take place especially with regard to bus and truck fleets, because a fuel cell motor is lighter than the motor of a battery-powered electric vehicle. This is particularly true of vehicles that travel more than approximately 450 kilometers per day.” However, for this to occur, the technology needs to be improved in terms of performance and cost. He further explains that the other objective of the laboratory is specifically to develop more efficient and cheaper parts for the vehicles having fuel cell motors. “For example, the layers of the fuel cell can be optimized via advanced numerical models and topological optimization. Added to this, the catalyst, from the catalytic layer, is made of platinum, a rare metal, which is worth more than gold and does not exist in Brazil. The challenge is to find more accessible options.”
In search of these solutions, the laboratory will use a technique developed by Lopes during the time he spent as an associate researcher at Imperial College London, UK, between 2012 and 2014. “The motor of a fuel cell vehicle receives oxygen on one side and hydrogen on the other. On the side where the air enters, we make a mixture with about 1000 ppm of ozone. In the catalytic layer, where the fuel cell reaction takes place, we place a pigment that, when interacting with ozone, emits light. This helps us to use a camera to visualize what is happening, and then compare how the oxidizing agent is distributed in fuel cell motors made of different types of materials, with different properties, and under different conditions, thus enabling the development of advanced numerical fuel cell models and their topological optimization,” Lopes goes on to describe.
The laboratory’s transdisciplinary team, which includes researchers from USP’s Poli, Institute of Physics (IF), Institute of Chemistry, and Institute for the Environment (IEE), will work together with Imperial College London in developing the various layers that make up the fuel cells, as described above, and they plan to keep moving forward. For example, “in the catalytic layer, the purpose is to discover whether more accessible materials, such as a mixture of iron, carbon and nitrogen, can replace platinum and be used by the automotive industry,” says Lopes. “This is a worldwide demand. Today, there is a research consortium in the United States, along the lines of the RCGI, dedicated to the development of these materials. Because there is not enough platinum to switch the entire world fleet of vehicles to fuel cells, we scientists have a lot of work ahead of us,” he concludes.