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Energy

Electricity from the Sun

Brazil turns to a more wide-ranging use of solar panels

ISMAR INGBERG / MPXIn Tauá, in Ceará, the first large Brazilian solar power plant. ISMAR INGBERG / MPX

Solar energy still has a smaller than 0.01% share in the Brazilian energy matrix, but is expected to grow significantly over the next few years. The sector is building up its structure in the country and the price of equipment at the global level is beginning to fall in the wake of an increase in production worldwide. Between 2009 and 2010, the industrialization of solar energy or photovoltaic systems grew by 118%, reaching a total power production of 27.2 gigawatts (GW), as reported by the journal Photon International. This figure represents the installed power of almost two Itaipu power stations. Even with the recent growth levels, which have exceeded 40% every year since 2004, this type of energy source still represents less than 1% on the planet as a whole. Worldwide expansion, which increased by almost 50% because of China’s production last year, raises many questions.

One of the obstacles to Brazil and other countries increasing their share in this type of energy is the high cost of solar panels and other equipment. A lack of mastery of the technology and a shortage of factories are also considered responsible for the difficulty in the advance of solar energy in the country. What is promising is new technology for assembling photovoltaic panels that has been developed by researchers at the Solar Energy Technology Center (NT-Solar) at the Pontifical Catholic University of Rio Grande do Sul (PUC-RS), coordinated by Professor Adriano Moehlecke and Professor Izete Zanesco. By treating imported sheets of purified silicon, the researchers managed to achieve greater efficiency in converting solar radiation into electricity. “The technology was proved by the manufacture of more than 12,000 solar cells in a pilot plant and the assembly of 200 photovoltaic modules,” says Moehlecke, the coordinator of NT-Solar. Cells were produced in the mini-plant that were as much as 15.4% energy efficient – a figure that represent the quantity of solar radiation used up by the equipment – while the worldwide average is 14%. “One of the differences in our technology is that we use low cost raw material, which reduces the final price.” Solar cells can be made from various materials, but 90% of the panels produced in the world today are made from silicon.

After proving that the national technology is viable for large-scale use,  efforts are being concentrated on establishing an industry in Brazil. “Since the end of last year a business plan is being prepared with this objective,” says Moehlecke. Development of the technology and the business plan was supported by the Research and Projects Financing Agency (Finep), Eletrosul and the Companhia Estadual de Distribuição de Energia Elétrica [State Electricity Distribution Company], a privately and publicly held company from Rio Grande do Sul. “The expectation is that over the next five months, we will have something definite including an agreement with investors for the construction of the industry.”

The horizon for new innovative products in this sector also includes solar cells that are sensitized with inorganic or organic dyes, the latter extracted from fruit, flowers and vegetables, as has been shown by research carried out by the University of São Paulo (USP) and the State University of Campinas (Unicamp). The group of Professor Neyde Murakami Iha, from the Photochemical and Energy Conversion Laboratory at USP, has focused on developing systems for storing and conserving solar power that have in their composition extracts of assai, jabuticaba (Brazilian grape) and mulberry, all fruits that have antioxidant pigments called anthocyanins. “The whole assembly concept of these systems is different, because this is not a semiconductor that absorbs light like silicon, but a dye that prevents the semiconductors from deteriorating,” says Neyde. The advantage of this system is that the processing is cheap and does not need special manufacturing plants. However, the efficiency of these cells is still only around 8%, which is well below that of current panels, which reach as much as 15%.

This line of research received a boost in 1988 when Professor Michael Gräetzel, from the Federal Polytechnic School of Lausanne, in Switzerland, created a cell that, instead of a single layer of titanium dioxide, was formed from small particles of the metallic oxide almost 20 nanometers in diameter, covered with a layer of pigment, which increased the absorption of solar light. Since then, various groups have dedicated themselves to transforming the invention into a product, the case of Bell Labs from the United States, as well as of European and Japanese institutions. The technology developed at USP was tested in demonstration cells, with funding of R$400,000 from Petrobras.

Solar panels on the roof of Munich airport, in Germany.

WERNER HENNIES/CORBIS/LATINSTOCKSolar panels on the roof of Munich airport, in Germany.WERNER HENNIES/CORBIS/LATINSTOCK

At Unicamp, the research group coordinated by Professor Ana Flávia Nogueira from the Institute of Chemistry is also working with organic or plastic solar cells in the laboratory, using polymers and other conducting materials. Another of the group’s lines of research that is fairly well advanced concerns titanium oxide cells sensitized with inorganic dyes. “To boost and continue this line of research, former members of the group founded the company Tezca, which has been installed in the Campinas High Technology Center,” says Ana Flávia. The proposal is to produce flexible solar cells in a few years time for application in laptops and smart phones, as well as in highway and urban road signs. The laboratory is also working on a project in partnership with Rede Energia, an electricity generator and distributor, for the development of solar cells of titanium oxide sensitized with chemical dyes, for application in windows and building façades, which is counting on collaboration from the Renato Archer Information Technology Center in Campinas. The company has invested around R$480,000 in the initial project.

Isolated battery
One of the main problems of the photovoltaic universe is that an efficient and cheap method for converting photovoltaic energy into chemical energy is yet to be found. “It’s the same path as photosynthesis when it transforms the sun’s rays into biomass, which is the natural way of storing chemical energy and that later results in ethanol, in the case of sugarcane. This way of storing for subsequent use still doesn’t exist for photovoltaic solar energy,” says the physicist from Unicamp, Cylon Gonçalves da Silva, CEO of Ceitec, a semiconductor company linked to the Ministry of Science and Technology, and author of the book, De Sol a Sol, a energia do século XXI [From Sun to Sun, the energy of the 21st Century] (Oficina de Textos), which focuses on renewable energy. It is precisely because of the lack of storage that solar energy has to be used throughout the day, continuously. The use of batteries for accumulating electricity is only justified in isolated areas in the countryside, for example, because they make the system much more expensive.

Less lacking in innovation and already present in various countries, such as Germany, Portugal and Spain, solar power stations or solar farms are reaching Brazil. These are panels installed alongside each other in rural areas, on the top of buildings, or on the roofs of parking lots or free areas in airports, which produce energy for the conventional electricity distribution network. Two Brazilian companies, MPX and Eletrosul, have taken the lead and are going to place the energy captured by thousands of solar panels on the national grid. On June 3, MPX, a company from the group that belongs to the businessman Eike Batista, announced the inauguration of a development in the municipality of Tauá, some 350 kilometers from Fortaleza, in Ceará state, that has initial power of 1 megawatt (MW). The plant has 4,680 photovoltaic panels made by the Japanese company Kyocera. MPX already has authorization from the National Electricity Agency (Aneel) to expand the capacity of the power plant to 5 MW. The energy generated will be connected to the national grid and will be sufficient to supply as many as 1,500 homes in the region. Overall, some R$10 million is being invested by the company, in addition to US$700,000 from the Interamerican Development Bank (BID).

In Florianópolis, photovoltaic cells, covering a total area of 8,000 square meters, will be installed on the roofs of the headquarters of Eletrosul and its parking lots to generate 1 megawatt of power, sufficient to supply the consumption needs of 570 of the city’s homes. A German government development agency, GIZ, in addition to contributing the concept of the project, managed to get funding from the KfW Bank of € 2.8 million to set up the power plant, which is also being supported by the Federal University of Santa Catarina (UFSC). “The public tender notice should be published by June to choose the company that is going to supply the equipment and do the installation,” says Jorge Alves, manager of the R & D Department at Eletrosul. The company also wants to sign partnership agreements to obtain efficient ways for purifying and laminating silicon. To do so, it plans to invest around R$20 million. “We want to mobilize researchers and enable laboratories to find efficient and low cost routes to obtain purified silicon that can be reproduced on an industrial scale,” says Alves.

064-069_energia solar_184-01The Brazilian solar energy agenda also provides for the possibility of installing photovoltaic panels on the roofs of the stadiums that are being prepared for the 2104 World Cup. Companies such as Cemig, in Minas Gerais, with Mineirão, and Light, in Rio de Janeiro, with Maracanã, are studying the installation of panels on the roofs of these stadiums, as happens in Germany and Switzerland. Professor Ricardo Rüther, from the UFSC, a photovoltaic energy expert, is also proposing the adoption of solar panels in airports. “Airports are large horizontal areas, free from shade that would serve as a showcase for other uses, functioning as a marketing tool for solar energy in the country, as happens in various airports in Germany, in the cities of Munich and Cologne,” says Rüther, whose research project into solar panels for airports is being funded by the National Council for Scientific and Technological Development (CNPq). If solar panels were installed in 66 Brazilian airports, it would be possible to have a total power output of 300 MW, enough to supply the whole of their power needs. A large part of the electricity in such places is spent during the day on air-conditioning systems.

In a country that has so much sunlight, photovoltaic technology is beginning to draw interest, because with use the learning curve is rising, costs are coming down and the world situation has changed. These are just some of the results gleaned from the workshop, “Innovation for Establishing the Photovoltaic Solar Energy Sector in Brazil,” held by the Energy Planning Interdisciplinary Center (Nipe) of the State University of Campinas (Unicamp), in March of this year. For Professor Gilberto Jannuzzi, the coordinator of Nipe, solar energy is growing in the world because China, which did not make photovoltaic panels until a few years ago, is now a great global producer and countries such as Germany, Portugal and Spain, which invested a lot in solar energy, either abandoned or modified their subsidies for this sector with the crisis of 2008. “This scenario made Brazil enter the circuit of equipment manufacturers once and for all,” says Jannuzzi. He also says that another factor is that the price of electricity is rising and the costs of photovoltaic energy falling. “This may lead to tariff parity in 5 to10 years time.” According to information from Professor Roberto Zilles, from the Institute of Electronics and Electrotechnology (IEE) at USP, the photovoltaic energy tariff is one and a half times more expensive than that charged for the electricity supplied by Eletropaulo, in São Paulo, and almost the same in Belo Horizonte. This calculation was done taking into account the 25-year life cycle of a panel, plus the cost of maintenance and the incidence of sunlight in the location (which changes according to the month and region of the country). The result is a figure to be compared with the cost of energy from the distribution companies.

In Brazil, the installed kilowatt (kW) costs about R$8,500. The average consumption of a four-person household is around 2.5 kW, which increases the figure to more than R$20,000. The increase in the scale of production of new materials and the need to generate greater levels of electricity without using fossil fuels really open up the way for solar energy. According to an information bulletin from the United Nations Intergovernmental Panel on Climate Change (IPCC), published in May, 80% of the energy produced in the world in 2050 will have to be renewable to comply with the carbon dioxide (CO2) emission reduction targets – and solar energy appears to be one of the most suitable alternatives for this purpose.

Natural environment
Researcher Enio Bueno Pereira, from the National Space Research Institute (Inpe), coordinator of the Atlas brasileiro de energia solar [Brazilian Atlas of Solar Energy], did some simulations that show how its use contributes to mitigating the greenhouse effect. In one of them he took as the basis one square kilometer in the Northeast Region, where the level of sunlight is very high, with few cloudy days. “Using photovoltaic panels that are just 10% efficient we would emit 98,500 tons of CO2 a year if we used natural gas,” says Pereira. In comparison with coal it would be 216,000 tons less into the atmosphere.

Even with the environmental advantages and the price of photovoltaic energy equipment in Brazil falling to levels that are more attractive to the consumer there still needs to be regulation to make shared generation feasible, when a residence or industrial or commercial establishment generates electricity for its own consumption via solar panels and sells any surplus produced to the grid. Thus, the owner of the equipment could generate this energy when he is not at home, for example, and get paid for it. In countries such as Spain, Portugal, Germany and the United States this possibility already exists. In Brazil, broader regulation that allows the connection of small producers to the electricity distribution network is being developed by Aneel.

Efficient house in Florianópolis: experiment at UFSC.

RICARDO RüTTER / UFSCEfficient house in Florianópolis: experiment at UFSC.RICARDO RüTTER / UFSC

According to Professor Rüther, with reimbursement for solar energy it will be easier for the owner of a residence or a commercial establishment to put his hand in his pocket to buy and install equipment on the roof of his house or company. He needs to be certain of receiving for any surplus produced. Around the world, 95% of the photovoltaic systems are connected to the electricity network of a city or region. In a study produced by the Center for Management and Strategic Studies (CGEE), which is linked to the Ministry of Science and Technology, and presented in 2010, called “Photovoltaic solar energy in Brazil: information for decision-making,” proposals were put forward for solar energy to gain new supporters in the country. After hearing hundreds of collaborators, including researchers and executives from institutions and companies, the authors, Moehlecke, from PUC-RS, Paulo Roberto Mei, from Unicamp, Rüther, from UFSC, and Zilles, from USP, also indicated the preparation and funding of Research, Development and Innovation (RD&I) programs that will make it possible for Brazilian industry to gain in competitiveness, in addition to encouraging the photovoltaic generation to be distributed by being connected to the electricity network.

Even though Brazil has the biggest reserves of good quality quartz, which is essential for obtaining ultra-pure silicon, for the time being the country only produces metallurgical silicon on an industrial scale, which is 98% to 99% pure and is used for the manufacture of steel, aluminum alloys and silicones. “Brazil has to get into manufacturing purified silicon,” says Mei. The main reason for this is its extremely high added value. While metallurgical silicon is sold for between US$1 and US$2 a kilo, purified silicon reaches more than US$60 a kilo in its crystalline form and as much as US$250 a kilo in the form of sheets used in the manufacture of panels.

In the 1980s, Heliodinâmica, from Vargem Grande Paulista, in São Paulo state, manufactured solar cells for export. In 1986 it accounted for almost 6% of global production. It was unable to stand international competition, whose prices were more competitive, and it closed its doors. In July last year, a team coordinated by physicist Bruno Topel, the founder and majority shareholder of Heliodinâmica, set up a partnership with Tecnometal Solar, from Campinas, one of the arms of the group from Minas Gerais, Tecnometal, which is involved in various segments of the equipment industry, for the development and introduction of a Brazilian photovoltaic project. In the first stage, sheets will be produced using imported silicon cells. “We’ve started a project that will lead to the complete vertical integration of the company within a year,” says Topel.

Possible good news for the future of solar energy in the country also appears in the Solar Technology Center at PUC (RS). There, 20 researchers are devoting their time to developing eight R&D projects. One of these projects’ partners is DuPont. “We signed an international agreement with the company to develop products for the photovoltaic area,” says Moehlecke. Du Pont announced in January this year that it will invest in a pilot R&D project in Brazil for producing fine films and other materials that go into solar panels.

The global expansion of solar energy is reaching not only roofs and open and desert areas, but also locations such as lakes and reservoirs. An example of this advance into water is happening in the State of California, as shown by The New York Times of April 19. Anchored and floating solar panels are installed on two lakes in Napa and Sonora. Surrounded by vineyards, these lakes, each of which covers less than two hectares, have 144 panels in Sonora and 994 in Napa. SPG Solar, from California, a company that installed the two aquatic solar energy farms and, according to the newspaper, Australian Sun Energy and Israeli Solaris Synergy, are betting on a global market for solar panels in reservoirs, hydroelectric dams and mines. The new development has already attracted the attention of possible customers in India, Australia and the Middle East. In Brazil there is still no project for dams, but Professor Rüther, from UFSC, has already carried out studies on taking advantage of the Itaipu dam. “It would be possible to generate almost 183 terawatts/hour per year (TWh), which represents 40% of the energy consumed in Brazil, if the 1,350 square kilometer dam were covered with solar panels,” says Rüther. “In Itaipu, for example, if the dam were covered it would be possible to save the energy of the hydroelectric power station by day, or substitute part of the thermoelectric power station operation that works with natural gas with that surplus energy.”

In the future, organic cells are likely to substitute silicon.

EDUARDO CESARIn the future, organic cells are likely to substitute silicon.EDUARDO CESAR

Hot radiation
The energy that comes from the Sun is electromagnetic radiation. It is formed by thermonuclear reactions that take place inside the stars and spread to the surface and from there into space. Temperatures reach 6,000º K on the surface of the Sun. “Models of solar evolution show us that the sun will continue producing this radiation for at least hundreds of millions of years or more,” says Professor Pierre Kaufmann, from the Radioastronomy and Astrophysics Center at Mackenzie Presbyterian University. Some 150 million kilometers from Earth, radiation makes the whole of this journey until it reaches the Earth’s atmosphere. “The radiation weakens in the atmosphere and because of this solar energy is more efficient in desert areas, where cloudless, dry weather predominates,” says Kaufmann.

He also says that the natural swings in solar activity that occur every 11 to 14 years have no significant influence on solar energy. “Variations in the radiation that reaches Earth are less than 0.1%.” In Brazil alone solar radiation is responsible for a theoretical potential of 115 million terawatt/hour of electricity generation capacity per year. “These are preliminary calculations, but show the astronomical potential, which is thousands of times greater than the national energy demand,” says researcher, Enio Bueno Pereira, from the National Space Research Institute (Inpe). This already takes into account preservation, inhabited and flooded areas and areas that are mountainous.

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