Electricity to maintain a middle class house with television, computer, refrigerator, microwave and a small air-conditioning appliance, as well as other electronic equipment, audio, even a hairdryer, and lamps for all the rooms. This is the function of the most recent fuel cell produced by UniTech, a company located in the town of Cajobi, 450 kilometers from São Paulo’s capital city. The equipment produces energy from hydrogen, and it has the capacity for generating 5 kilowatts (kW) of maximum power in electricity. It is the company’s first model adapted for commercial use, and its should serve as a basis for scale production.
Previously, UniTech had produced several prototypes with a lower capacity and collaborated with a 1.5 kW cell produced by the Minas Gerais Energy Company (Cemig) (see Pesquisa Fapesp nº 70). The new cell is a stationery generator of electricity assembled in a rack that measures 1 meter and 30 centimeters (cm) in length by 84 cm in width and 1.10 meters in height. The heart of the equipment, which is the fuel cell itself, measures 47 cm in length by 30 cm in width and 30 cm in height. It is intended for a company from the energy area that financed the equipment. The company’s name cannot be disclosed yet, due to a non-disclosure agreement.
The cell has been prepared to use the hydrogen used from the reform of natural gas or of ethanol. To do so, the company that is going to operate the cell has now bought a reformer, a device that breaks down the molecules of the natural gas (it has molecules with one atom of carbon and four of hydrogen, CH4), separating the hydrogen and releasing the carbon, which binds with oxygen in the atmosphere and is transformed into carbon dioxide (CO2). “The quantity of this pollutant gas emitted by the cell is far lower than the standards established for combustion engines, for example”, says chemist Antônio César Ferreira, who conceived and owns UniTech.
The cell attains zero pollution when it is fed only with hydrogen. This gas can also be extracted from gasoline, from methanol, and from ethanol, the alcohol used in automobiles in Brazil. Researches carried out all over the world are testing prototype reformers for this kind of fuel, including at the Physics Institute of the State University of Campinas (Unicamp). Hydrogen can also be obtained from the electrolysis of water, when hydrogen and oxygen are separated by an electrical discharge. But this process is still regarded as very expensive, for requiring spending with electricity. Besides the total absence, or tiny fractions, of pollutants, the cells also do a silent job, unlike the generators that work with diesel or gasoline, and even the thermoelectric power plants, all of them excessively noisy. Silent and non-pollutant, fuel cells can be implemented in various environments that need electricity.
“To start with, mainly in hospitals and shopping centers, they should be used to lighten the load on the network. When production reached a large scale and the costs come down, cells may replace any electricity producing generator”, says Antônio César. Fuel cells supply clean energy without fluctuation, ideal therefore for running computers and electronic equipment, including surgical centers, which eliminates voltage stabilizers and UBS. “The United States recently installed five 200 kW fuel cells to run a credit card security system, precisely because it provides for a higher degree of reliability with a lower fall in energy.”
Even in areas distant from the major urban centers, fuel cells prove to be a reliable and important alternative. “The isolated populations of the northern, northeastern and central-western regions of Brazil, which today use generators that run on diesel (a fuel that is transported by trucks and even by boat) could stock and use to work the cells hydrogen extracted from water by means of electrolysis produced with solar energy. “An area of 100 square meters (m²) would produce sufficient hydrogen for a house, because it is possible to stock hydrogen in cylinders and use it at night, or when the capture of solar energy is insufficient, on cloudy days or in the winter. This would avoid the costly and difficult process or storing electricity obtained from solar of wind energy, traditionally done with the use of batteries. “The cost of the kilowatt hour (kWh) of electricity produced with the solar energy system, electrolysis and fuel cell should work out at around R$ 0.41. This complete system for generating electricity is also being developed by UniTech.
The price of a fuel cell is of course still higher, when compared with the traditional generators of energy. Antônio César calculates that the price of a typically residential cell with 5 kW would cost about US$ 4,500 (almost R$ 13,500.00). For the consumer, with cells coming off a production line, the installed kW would cost between US$ 1,000 and US$ 1,500, the same cost as the installation of a thermoelectric power. The price is expected to come down when the few companies producing this kind of equipment in the world reach large scale production.
“For the operation of the cell, the cheapest option is natural gas, which costs, at its lowest, R$ 0.76 the cubic meter (1 m³), a portion sufficient to produce 4 m³ of hydrogen and consequently 4 kWh of electricity. Accordingly, the kWh of energy would be R$ 0.19.” This amount would increase to R$ 0.65 should consumption rise to over 40 m³ per month. As a comparison, the price of the kWh of electricity supplied by the electricity companies in São Paulo, for residences, is R$ 0.30. At the moment, the option for buying hydrogen is more expensive, because the m3 of this gas costs about R$ 0.60, a price that varies according to the volume used.
Another factor that counts in favor of the cell is the supply of hot water. As this equipment works at a temperature of around 70ºC , it needs water to cool it down. From this process, hot water is left over, which can be used in showers and faucets, eliminating the use of electricity with these apparatuses. “The use of water to generate heat raises the cell’s energy yield to 70 to 80%. Without the use of water, this falls to a level between 45 and 55%”, says Antônio César. This yield is the result of the electrochemical transformation of hydrogen into electricity, and the losses with the generation of heat, As a comparison, the yield of gasoline in an automobile engine, for example, is 21%. With diesel, it goes up to 30.35%. The rest is lost.
Although they have so many attributes, fuel cells are still in a process of evolution and testing around the world. One of the results established is the periodic maintenance of the cell, which should have its electrodes changed every eight years. This is in the case of the kind of cell produced by UniTech, called proton exchange membrane, or PEM for short, in which the membrane is a polymer also known as a proton-conducting polymer (sulfonated polytetrafluoroethylene). The PEM is inside a sandwich, surrounded by catalytic agents and graphite electrodes with positive and negative poles, like a battery used in automobiles, which work like separating plates, conducting the electrons away from the plates and generating electricity. The hydrogen protons, in turn, produced at one of the electrodes (anodes) pass through the membrane and join the atmospheric oxygen at the other electrode (cathode), forming water.
Production in series
The electrodes and the catalytic agents are the main components to be manufactured by companies that intend to produce fuel cells. The membrane is already to be found on the market, to be purchased like an item of supply. That is why the manufacture of the electrodes in an automated manner and in scale is one of UniTech’s objectives. “We already have the technology for the components and assembly, now we have to automate the factory”, the entrepreneur says. The initial idea is to produce at least a thousand 5 kW units a year.
Antônio César, for the time being, is working with another two engineers and three technicians. He began in 1998, through a project of the Small Business Innovation Research Program (PIPE), after having spent nine years in the United States, working as a researcher at the University of Texas and in companies that were carrying out projects for the North American Space Agency and for the American army. “I returned to Brazil for good and to my home town because I got the scholarship and the project from Fapesp”, Antônio César says. “I had invitations to carry on working there, but I preferred to come to Brazil. Were it not for the PIPE, I wouldn’t have come back.” Later on, UniTech also received R$ 400,000 in financing for producing the dies of the separating plates from the Energy Sectorial Fund (CT-Energ), administered by the Financier of Studies and Projects (Finep), of the Ministry of Science and Technology (MCT).
Advanced materials for manufacturing bipolar separators for fuel cells with an ionic conducting polymer (nº 97/07401-6); Modality Small Business Innovation Research Program (PIPE); Coordinator Antônio César Ferreira – UniTech; Investment R$ 197,184.64 and US$ 77,482.00