Globally, there has been a growing demand for sustainable energy sources in recent years. Also known as clean energy, essa geração ocorre quando há preocupação com redução dos impactos ambientais relacionados a atividade. Assim, utiliza-se como fonte, recursos renováveis, como o sol, o vento, a água, o hidrogênio verde, a biomassa, dentre outros.
In general, the Brazilian energy matrix is expanding and exceeds 7 Gigawatt (GW) em 2023. Destaca-se que uma fração de geração de energia no país, em operação, é proveniente das Usinas Hidrelétricas (UHE) com percentual de 52,27%, já as Usinas Fotovoltaicas (UFV), correspondem a 5,26%. Em contrapartida, em relação as usinas em construção, as UHE indicam apenas 0,26% e as UFV 37,30 %. Em relação as em construções não iniciadas, as UHE indicam 0,23% e as UFV 82,33% (ANEEL, 2023).
Therefore, there is a significant forecast of future investments in UFVs. The conventional photovoltaic system typically uses land for deployment and, in some cases, requires the removal of native vegetation.
According to the World Bank Group(2018), the implementation of floating photovoltaic systems in water reservoirs is a relatively new technology, initiated in 2007 in the city of Aichi, Japan. Over the years, various countries have invested in this system on a small scale, including France, Italy, the Republic of Korea, Spain, and the United States. Large-scale floating installations, exceeding 1 Megawatts-peak (MWp), began to emerge in 2013. In a short period, the floating solar market spread worldwide, including Brazil, with a strong presence in China, Japan, and the United Kingdom.
Therefore, the overall layout of a floating photovoltaic system consists of modules connected in series, with materials designed to support the weight of the panels and the workers who perform maintenance. This structure also includes anchoring systems and electrical cables interconnected to the power center, where the energy is inverted for distribution.
Floating UFVs in hydroelectric reservoirs offer several advantages over conventional land-based systems, including 1) utilizing a portion of the available water surface instead of land; 2) the possibility of solar tracking; 3) reducing evaporation, dust on the panels, and the growth of microalgae in the reservoir; 4) even during significant drought periods, photovoltaic generation continues; and 5) utilizing existing reservoir infrastructure such as substations and transmission lines that carry the energy produced by the hydroelectric plant.
On the other hand, before installing floating UFVs, there are some key considerations: 1) comparing costs with land-based systems; 2) assessing historical data on potential adverse conditions such as strong winds (which can cause structural damage) and ensuring optimal positioning and sunlight exposure for maximum electromagnetic radiation (light and heat) capture; 3) conducting specialized on-sitesocio-environmental studies in advance; and 4) obtaining relevant environmental permits and licenses.
Turning our focus to investments related to floating UFVs in Brazil, the largest project installed in a reservoir is located in Sobradinho, Bahia. The first phase of this project was inaugurated in August 2019 by the São Francisco Hydroelectric Company (Chesf) in partnership with the federal government. Segundo a Chesf, 2019, o projeto conta 3.792 módulos de placas solares e área total de 11 mil m², com geração de 1MWp, o que equivale ao abastecimento de até 2.000 residências populares. Prevê-se uma segunda etapa com projeção de geração de 2,5MWp e investimento total de R$ 56 milhões.
According to Thadeu Carneiro da Silva, director of the Companhia Energética de Minas Gerais (Cemig), Geração e Transmissão, investimentos que envolvem a combinação de duas fontes energéticas diferentes (projetos híbridos), são uma tendência atual, pois permitem o melhor aproveitamento dos recursos (CEMIG, 2021).
Looking towards the near future, Cemig plans to invest in the implementation of floating UFVs in some of its reservoirs. The most advanced project to date is the Três Marias power plant. Other floating UFVs will be installed in the Cajuru, Theodomiro Carneiro Santiago (formerly Emborcação) reservoirs, and a hydroelectric plant yet to be announced. On September 20, during the Ecoenergy Congress, director Thadeu Carneiro mentioned, "We are using less than 1% of our water surface to generate these 350 MWp. It's a very small, almost negligible ratio between the covered area and generation compared to our total water surface” (EPBR,2023).
Therefore, the importance of investing in hybrid projects, such as floating photovoltaic systems in hydroelectric reservoirs, is evident. This combination brings significant advances in sustainable energy generation in Brazil and around the world.
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