Environment
In Italy, geothermal power plants are creating electricity and heating homes. But this strategy faces challenges to becoming a widespread climate solution.
ByAgostino Petroni
Published February 2, 2024
LARDERELLO, ITALYOn a chilly autumn morning in the Italian countryside near Larderello, Tuscany, the misty landscape reminded me why the area is nicknamed Valle del Diavolo, or the Devil’s Valley. Supposedly the inspiration for Dante Alighieri’s Inferno, the land here is a web of natural cracks in the rock that let a mix of steam and gasses reach the surface. Volcanic vents called fumaroles and geysers sprayed white clouds into the air.
Unlike the rolling hills, vineyards, and cypress-lined roads of other parts of Tuscany, the landscape here is studded with dozens of gray cooling towers puffing white vapors. The deafening roar of a car-sized turbine at the Valle Secolo geothermal plant stamps out any sense of tranquility, but its violent spinning transforms steam rising from 3,300 feet below ground into energy for 150,000 families in the region.
“The more steam we manage to extract, the fewer oil tankers will travel,” said Geoffrey Giudetti, a geologist working for Enel Green Power, Europe’s largest geothermal operator, which runs Valle Secolo and 33 other Tuscan geothermal plants. About 30 percent of Tuscany’s electricity comes from this underground energy source. After the electricity production is done, the leftover steam heats water for nearby districts.
This energy harnessed from underground has recently proved a vital resource. Russia’s invasion of Ukraine underscored Italy’s dependence on Russian fossil fuels, and as the war raged on, Italian electricity prices skyrocketed. In 2022 Italians bore some of the world’s highest household electricity bills. Factories scaled down production, and households resorted to turning down their heaters.
But residents of the Larderello area spent the winter in warm homes, Giudetti says, thanks to the local geothermal plants harnessing boiling vapors 24/7.
Bruno Della Vedova, president of the Italian Geothermal Union, is convinced that other Italian regions could benefit from such a resource. According to a 2015 Italian government report, much of the country could run on energy converted from underground heat sources.
As the world looks to transition to renewable energy, Tuscany’s century-long history of harnessing geothermal resources stands as a beacon of hope for the country’s energy strategy.
Pulling energy from the Earth
While countries like Iceland and Kenya are taking advantage of their geothermal resources, the industry’s growth has stagnated in Italy. High set-up costs and difficulties in extraction—which, done incorrectly, can result in heavy economic and environmental loss—present significant barriers. And new plants often run into opposition from nearby communities over health concerns.
According to Della Vedova, Italy sits on a geothermal sweet spot. Situated where the African tectonic plate meets the Eurasian one, the Italian peninsula is atop a complex geological system where molten rock is pushed toward Earth’s surface.
Below Larderello, Giudetti says, a vast reservoir of steam and water, spanning 1,600 to 14,000 feet deep, is trapped between Earth’s interior heat and a layer of clay-heavy rocks that act like a pot lid. High temperatures lead to the formation of steam directly inside the reservoir, providing a significant source of energy.
But while heat from Earth’s core is practically endless, the fluids it heats within the planet are not.
“Overtime, [the reservoirs] lose pressure and flow rate, and therefore lose productivity capacity,” said Della Vedova. He says Larderello’s power capacity shrinks by 20 megawatts annually, even if much of the extracted water is reinjected underground. Most of such loss, he says, is compensated by the newer plants’ efficiency improvements, but restoring underground water supplies and using them sustainably is critical for the future.
“We can’t exploit a geothermal resource,” Della Vedova says. “We need to cultivate it.”
A history of geothermal
“We invented geothermal energy,” says Giorgio Simoni, a local technician who has worked in geothermal for the past 32 years. In 1904 Pietro Ginori Conti, an Italian aristocrat, turned on five light bulbs with a generator powered by heat escaping Earth’s surface in Larderello. A decade later he built the world’s first geothermal plant.
Today, Enel Green Power has drilled 507 extraction wells to feed its plants. The formerly state-run company was privatized in the 1990s, and the Italian government changed regulations in 2010 to allow other private companies to study and extract geothermal resources. But only Enel has constructed new plants.
Understanding where to find this underground resource and build a plant is easier said than done. Searching for a geothermal reservoir is like drawing blood from a patient, Della Vedova explains: nurses don’t randomly stick needles hoping for the best, but carefully search for specific veins. And studying a reservoir to see if it has the right temperature and pressure to produce enough electricity can cost millions of dollars, Giudetti says, with a 50 percent chance of a negative outcome.
This initial economic barrier stops several countries or private enterprises from starting geothermal exploration in the first place, even if, according to Manzella, long-term costs are “comparable or even lower than other renewable technologies.”
Vapors fuel worries
The vapors shooting off the Tuscan geothermal cooling towers have also raised health concerns among some locals.
“We do not have city traffic or chemical industries; still, we have high cancer and mortality rates,” said Velio Arezzini, a 75-year-old native of Abbadia San Salvatore, a hamlet a few miles from two geothermal plants.
Arezzini, the spokesperson for NOGESI, the network against speculative and polluting geothermal energy, bases his fears on a 2012 study by the Regional Health Agency that recorded local health anomalies. (A 2016 follow-up study dismissed any relationship between the cooling towers and a higher risk of mortality or hospitalization.)
Della Vedova points to an overlap of factors that could impact people’s health, particularly the fact that these valleys, a geothermal hotspot, have chemicals such as mercury embedded in the ecosystem naturally. He says that intercepting steam underground could even reduce surface emissions, since the steam doesn’t soak through rock layers where it can pick up pollutants.
Enel Green Power has installed emission abatement systems on their facilities to cut down the plants’ hydrogen sulfide and mercury emissions. Still, according to a 2019 study, the possible impacts of emissions from the plants in the area should be investigated further.
Community use
Mario Tanda, a 56-year-old farmer, pointed at a gray pipe running toward his cheesemaking facility in Monterotondo Marittimo. Half a mile away, the Nuova San Martino geothermal plant that Enel built on his family’s confiscated land spit out clouds of vapor.
“Every production cycle needs energy,” Tanda said. His father opposed the construction of the geothermal plants, but in 2007 Tanda connected his farm to the plant with a piping system to bring in cheap heat to process the milk of his 800 sheep into pecorino cheese.
A few miles away, in Sasso Pisano, 71-year-old Edo Volpi makes beer, and in Monterotondo Marittimo, Giacomo Anterminelli grows zucchini and cucumbers in greenhouses. They both run their productions by using leftover heat coming from nearby plants.
“If we do not use this energy, it would be wasted,” Tanda said. As Italy and other nations grapple with the transition to clean energy, the roiling innards of the planet may provide a critical lifeline.
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