Geothermal in agrifood
Federico Turrisi
Enea Cosentino, Production Manager of Parvus Flos.
uscany is famous for its food and wine tradition, for its artistic and cultural heritage, for its breath-taking landscapes. But this region is also known for being the cradle of geothermal energy. Here, the heat generated within the Earth was used for the first time in the world to produce electricity.
Over 30% of the energy needs in Tuscany is now covered by 35 geothermal plants, located in the eight cultivation concessions across the geothermal areas of Larderello-Travale and Mount Amiata, for a total of over 900 MW of installed power.
“It is certainly not an easy time. We must face the increase in the prices of electricity for raw materials, not to mention the increase in packaging materials, seeds, topsoil and fuel prices. Fortunately, geothermal energy can lend a hand".
These are the words of Enea Cosentino, 47, production manager of Parvus Flos, a social cooperative founded in 1999, that produces “zero impact” basil in the heart of Tuscany. We met him in late July.
The story of Enea and Parvus Flos is closely related to geothermal. The greenhouses, in which basil is cultivated, extend over 20,000 square meters of surface. All around the facility there is dense vegetation. In the background you can see the profile of the towers of one of the geothermal power plants in the municipal area of Radicondoli.
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Producing basil in a sustainable way
Zero impact, we said. But how? The peculiarity of Parvus Flos (which in Latin means “little flower”) is using geothermal fluid to heat the greenhouses during the cold season, reducing CO2 emissions.
"Outside the greenhouses there is a heat exchanger that uses steam from geothermal power plants. The steam releases heat by contact with the greenhouse heating water, which is pushed through the pipes", Enea shows us. "The water enters at 90-95°C and exits at 60-70°C after having transferred its heat to the spaces. Once returned to the heat exchanger, the water is brought back to the initial temperature and returns to the greenhouse. So the cycle restarts".
In this circular process, there is no combustion of gas or other materials. And this also implicates important economic savings: "For a company that deals with greenhouse cultivation, the first expense on the budget is personnel, and the second one is heating. The use of geothermal steam allows us to save about 30%".
Regarding the use of electricity, Enea underlines that Parvus Flos is powered 100% from renewables. “We have installed 100 KW of solar panels, which cover about a quarter of our needs. The remaining three quarters are covered by the nearby geothermal plants”, he adds.
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The cooperative produces about 45 tons of cut basil (leaves and twigs) and 650,000 units of basil in pots per year. The defense of the plants is conducted through integrated pest management, which involves a drastic reduction of pesticides ("we use chemistry only if we have no other alternatives").
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Despite being a small company, Parvus Flos has become the main supplier of basil for the large-scale retail trade in Tuscany. “For us it’s less profitable, but we have a guarantee on payments”, Enea says, motivating the choice. For him, sustainability is to be understood at 360 degrees: environmental, economic, but also social. Parvus Flos has 15 employees; one third of them are socially disadvantaged people, such as convicts, disabled and asylum seekers.
Geothermal energy: an ally to make Tuscany carbon neutral
Reducing our dependence on fossil fuels is necessary to face the current energy crisis and to achieve carbon neutrality by 2050. This is why geothermal energy is of great interest. As the International Energy Agency shows, this technology is not on track with the Net Zero Emissions by 2050 Scenario, which requires 13% annual increases in geothermal electricity generation globally over 2021-2030 (it increased an estimated 2% year-on-year in 2020).
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As for Italy, Tuscany represents a truly unique case for the geo-morphological characteristics of its territory, and here there is the greatest potential for development. "Tuscany has all the possibilities to be the first region to achieve a true ecological transition by fully utilizing its renewable energy potential: geothermal, solar, wind and hydroelectric", professor of the Department of Earth Sciences at the University of Pisa Paola Marianelli explains. “A recent study confirms that the production of electricity from geothermal sources by 2050 can double up with the use of geothermal resources located in the subsoil of our region, in particular in the area of Larderello and Mount Amiata without significant environmental impact”.
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Geothermal energy offers undoubted advantages and technological innovation promises to make it even more efficient. “It guarantees a constant production of electricity over time, unlike solar and wind power. Furthermore, with the new generation of plants (ORC - Organic Rankine Cycle), we’ll be able to have zero emissions of carbon dioxide and polluting gases", professor of the Department of Physical, Earth and Environmental Sciences at the University of Siena Marcello Viti explains.
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But reality is more complex and there is also the downside. "Among the weaknesses of geothermal energy there is certainly the fact that the development of new geothermal plants requires long times and high costs for exploration and drilling. Moreover, the geothermal activity could cause microseisms, which in any case are not perceived by the population, but are recorded by the instruments”.
Who says no
Not everyone is enthusiastic about the idea of witnessing a further expansion of geothermal energy in Tuscany. Among those who oppose the construction of new plants, for example, there is Genuino Amiatino, a collective born ten years ago in the Amiata area to protect the biodiversity of the territory. Its slogan is “for food sovereignty, against harmfulness”.
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“Nimby syndrome? We are against extractivism in general, not only against geothermal energy. The territory is not a mine to be exploited unconditionally”, two members of Genuino Amiatino tell us during a telephone interview. They ask not to be quoted by name, but to be quoted as a collective. "Under the pretext of the ecological transition, they want to promote the construction of other power plants, but we cannot tolerate this because it would mean transforming Amiata into an industrial district even more".
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Genuino Amiatino and other local committees created to oppose the construction of new geothermal plants are also concerned about the impact on the landscape and the release of harmful substances. "In addition to the danger for public health, geothermal energy is a type of production that puts at risk all other activities in the area, from agriculture to tourism. The only motivation is profit", the collective reiterates.
The InVetta epidemiological survey, conducted on over 2,000 inhabitants in the Amiata area, seems to dispel doubts about the harmful impact on human health of emissions from geothermal plants. The project was born as an in-depth activity that follows a series of studies on geothermal and health in Tuscany started in 2007-2008.
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"InVetta has not found a significant contribution of exposure to emissions from geothermal plants on the respiratory health of the resident population. No association was found with other health problems investigated, such as cancer, diabetes, cardiovascular and kidney disease", coordinator of the epidemiology observatory of the regional health agency Fabio Voller says.
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However, further research is still ongoing. The focus is now more on the metals issue. “On the one hand, InVetta has confirmed the widespread presence of arsenic and mercury, linked both to the geological nature of the territory and to anthropic activities. On the other hand, it has drawn attention on thallium, a metal that undoubtedly deserves more studies. We need to investigate the role of food exposure, linked to the use of surface water for direct use or irrigation and to the consumption of local products which, due to bioaccumulation, could contain relevant levels of metals”.
A fragile balance
Let’s come back to that expression mentioned at the beginning: zero impact. Indeed, every human activity has an impact. We need to weigh up pros and cons. Geothermal plants are the opposite of a beautiful landscape, of course, but at the same time they have a strong influence on the production of electricity and the employment rate in southern Tuscany.
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The main challenge is to combine various aspects: respect for environment, high quality agriculture, tourism, industry. But, first of all, never forget to listen to the local communities. “Building a new power plant near an area full of restaurants and agritourisms is non-sense”, Enea Cosentino says.
“We don’t step on somebody’s toes. Logistically we pay a higher price to transport and to distribute our goods but our headquarters is necessarily here, near the geothermal wells and far away from the medieval town of Radicondoli”.
The message of Enea is clear: “I lived here for 22 years. Tourism and geothermal energy can coexist harmoniously”.
December 2022