- Recent studies have shown that agrivoltaic systems, which combine solar power generation with food farming, can be a sustainable development strategy in water-stressed regions.
- A pilot project in Brazil’s semiarid northeast region consists of a series of solar panels, underneath which vegetables can be grown and fish and chickens raised, offering both food and energy security for users.
- If scaled up, agrivoltaics could also generate electricity for the whole of Brazil, according to the project’s proponents, while at the same time boosting food production and allowing for the restoration of degraded or desertified land.
- The pilot project of the system, known as Ecolume, has shown promising results, but there has been little interest among Brazilian policymakers to replicate it more widely or even promote it as a solution for food and energy production challenges.
High levels of food, water and energy insecurity brought on by socioeconomic issues and exacerbated by climate change have been driving research groups to find new solutions. A 2020 study from Brazil shows that agrivoltaic solar systems can be a solution with great potential. These systems combine food production and solar power generation in the same physical space to maximize results and reduce the use of natural resources.
Brazil’s first agrivoltaic system is called Ecolume. It was developed by a network of more than 40 Brazilian researchers and funded by CNPq, the National Council for Scientific and Technological Development. A pilot project was installed at the SERTA agroecology school in the municipality of Ibimirim, in Pernambuco state, in 2019 under the coordination of the Pernambuco Agronomy Institute (IPA).
IPA climatologist and Ecolume coordinator Francis Lacerda says the project evolved due to concerns over how to produce enough food in Brazil’s semiarid regions. These regions have historically experienced water shortages due to drought and rising temperatures, and ensuring year-round food production has become a problem.
Lacerda says researchers also wanted to prove that, despite having the lowest human development index in Brazil today, the northeastern region of the country is abundant in natural resources like sunshine and the biodiversity of the Caatinga scrub forest. “Ecolume helped us develop a production model that leverages [the region’s] potential and resources,” she says.
Food and water sustainability
The Ecolume Agrivoltaic System, which goes by the acronym SAVE, makes the most of the scant local water resources by reusing water and collecting rainwater. It consists of 10 photovoltaic panels that cover 24 square meters (258 square feet), installed at a height of 2 meters (6 feet) above the ground. An aquaponics system is installed below the solar panels for combined cultivation of produce and fish, together with a chicken pen.
Production engineer Heitor Sabino helped install the Ecolume system at the SERTA school. He says the model improves agricultural production in semiarid regions because the shade from the solar panels protects the crops from excessive heat, providing a milder, more humid microclimate that’s ideal for plant and animal development. The shade also helps reduce water loss from evapotranspiration, and the combined aquaponics and water reuse system allow for more sustainable irrigation than in conventional farming.
In simulations carried out by Ecolume researchers, the agrivoltaic system produced up to 70% more vegetables and lowered the need for water, depending on the crop and environment. A study carried out at the University of Arizona, in the southwestern U.S. — a region that also experiences water scarcity — showed yields two to three times higher for some fruits and vegetables planted under solar panels. The SAVE water recycling and treatment systems also showed a 90% savings in water used for irrigation.
Lacerda says SAVE is proof that farming can be adapted to the semiarid climate of Brazil’s northeast, where rainfall patterns have always been highly variable, and which is now becoming drier and hotter due to climate change. SAVE makes it possible to produce healthy food year-round with little water and no pesticides under these conditions, its proponents say.
Ecolume was developed for small-scale production of crops, mainly vegetables, and electricity. It can supply the basic needs of a family of about seven people or generate annual revenue of around 11,000 reais ($2,100). Sabino says that if the system were replicated as a network of small units distributed throughout Brazil’s northeast, it could help solve the region’s serious hunger, nutrition and power problems.
Lacerda says the system could also combat other issues in the region. Despite the Caatinga’s rich biodiversity of plant and animal life, 46% of its native vegetation has been destroyed, mostly for fuelwood and for farming and cattle ranching. Combining both energy and food production in a single area with an agrivoltaic system means reducing deforestation and land use while also freeing up land that can be reforested and restored. This can help mitigate the region’s climate crisis, Lacerda says.
“Today the Caatinga is being deforested to create photovoltaic power mega farms, but this is counterproductive,” Lacerda says. Not only is this type of electricity production environmentally unsustainable, she adds, it’s also less efficient and costlier than the agrivoltaic model.
Studies have shown that excessive heat causes solar panels to lose their power-generating efficiency. Farming beneath the panels is a potential solution because the water vapor generated by plant transpiration lowers the air temperature and keeps the panels from overheating. This, in turn, increases their efficiency.
Ecolume simulations showed an average increase of 75 kilowatt-hours in solar power production following the installation of aquaponic systems beneath the panels because of their cooling effect, Sabino says.
It’s also an inexpensive production model — the 24-m2 SAVE pilot project, for example, cost about 20,000 reais ($3,750) — which would make it economically feasible to farm degraded or desertified land while offering power security for those regions — or, indeed, the whole country, Lacerda says. “If we were to install similar small groups of solar panels [like those used in the Ecolume model] exclusively on existing degraded or desertified areas, we would produce enough energy for the entire country,” she says. At the same time, she adds, “creating shade for these areas makes it possible to recuperate the soil.”
Similarly, researchers at Oregon State University concluded that if agrivoltaic systems were installed on less than 1% of farmland in the U.S., they could supply 20% of the country’s electricity demand. This would have the added benefit of a significant reduction in carbon dioxide emissions.
Little interest from policymakers
“We have already proven that the Ecolume Agrivoltaic System promotes food, water and energy security,” Sabino says. “What we need now is investment, especially public funding, to be able to train more people and install more systems.”
But the Ecolume “family unit” model for small distributed units — which would generate environmental, social and economic benefits for a large number of people in the semiarid northeast and possibly other parts of Brazil — has still not caught the attention of policymakers. Lacerda says she has presented the project at hearings before both the lower and upper houses of Congress, and has discussed it with ministers. But to date, she says, “there is no interest.”
Even INSA, the National Semiarid Institute, which funded the network at the beginning of the project, has not invested in promoting it. There’s no mention of the Ecolume Agrivoltaic System on the Renova Semiárido digital platform developed by INSA in 2021 to publicize renewable and sustainable energy projects in the region.
Neither was the system mentioned during the digital event Conecta Semiárido recently organized by INSA to connect players and discuss opportunities in the renewable energy production chain. The institute’s current director, Monica Tejo, did not respond to Mongabay’s requests for comment.
According to Lacerda, current public policy continues to support the old paradigm of large-scale production and monocultures in models aimed at concentrating wealth. This ends up discouraging replication of projects like the Ecolume system, she says.
“We need public policy to incentivize this new system,” Lacerda says. “As soon as possible.”
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Banner image: An agrivoltaic system in Colorado in the U.S. Image courtesy of the U.S. Department of Energy.