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Geothermal energy

Geothermal energy

From the Etruscans to the hamlet of Larderello, straight to Dante: geothermal energy owes a lot to Italy. The heat from earth’s crust has been harnessed to serve many purposes since the dawn of mankind. The real breakthrough though came at the start of the nineteenth century when a puff of steam turned on five light bulbs…

About geothermal energy

From the Earth’s heat comes energy

The Greek etymology of the term says it all: geō, Earth, and thermós, heat. The heat coming from deep within Earth’s crust transforms water in steam, which has accompanied mankind along its evolution to serve many different purposes: to heat, to cook, to power spas. In the eighteenth century, men pioneered the first industrial uses of geothermal energy and by the start of the nineteenth century, it opened the door for electricity.

Right until the sixties, the world’s hotspot of geothermal energy was the small Tuscan hamlet of  Larderello, which held the world record for installed capacity until the eighties, when this kind of energy sources went global on a large scale. In the last decade, countries like the United States and Iceland made the most of their own large geothermal resources, exploiting steam for household heating purposes. Suffice to say that 95% of Icelandic households are heated thanks to steam collected straight from the earth’s crust.

According to data from the 2019 IRENA report, geothermal energy’s contribution to the global renewable capacity amounts to 13 GW. Geothermal energy is less spread out than other renewable sources since not all territories hold large pockets of trapped heat in their subsoil. Fortunately, these constraints don’t hamper the development of its potential. Following the 2015 COP21 (Conference of Parties) conference in Paris, the Global Geothermal Alliance was established with the UN’s blessing to fast-track this renewable resource in a quest to hasten the energy transition process.

The history of geothermal energy

Going along with literature, medicine, and technology

The dawn of geothermal energy

The relationship between mankind and the Earth’s energy has primeval roots. Since the stone age, men built their own dwellings near active geothermal areas to use by-products of volcanic activities, harnessing heat to cook and… enjoying the benefits of thermal baths!

From Etruscans…

Etruscans built most of their villages near geothermal vents and used their by-products like alabaster, travertine, iron oxides and, thermal muds as bargaining chips. The oldest remains of the Sasso Pisano Etruscan thermal complex in Tuscany, actually date back from the III century BC.

…to Romans

The passion for spas and baths is one of many quirks the Etruscans passed on to the Romans. Tuscany and its “Valley of the Devil” came to prominence for its natural geysers and fumaroles. Aquas Volaternas and Aque Populanie – today’s Larderello and Sasso Pisano – feature as major thermal baths in the “Tabula Peutingeriana”, the Roman Empire’s own road map.

The decline

After the demise of the Roman Empire, thermal baths and the use of by-products of geothermal energy experience a strong decline for a good part of the Middle Ages.

An “infernal” inspiration

Versan le vene le fummifere acque / per li vapor che la terra ha nel ventre / che d'abisso li tira suso in alto”. Such a poetical description of Larderello’s environs was crafted by none other than Dante in his book of rhymes. Was Dante probably inspired by its own native land to create his masterpiece - the Inferno?

The Tuscan renaissance

Balneotherapy and the use of hydrothermal minerals and other by-products of earth’s heat saw a gradual comeback in Italy, especially in Tuscany. Following a period of local skirmishes between the towns of Florence and Volterra in what is known to this day as the “Borax Territory”, the Medici Family took control of this piece of land and its geothermal resources.

Giving health a chance

In the Tuscan geothermal hotspots of Monterondo Marittimo and Castelnuovo Val di Cecina, Boric acid is discovered, representing a breakthrough for its widespread medical application in the treatment of eye diseases. Hence, the fine-tuning of the extraction process becomes an important task to be performed.

De Larderel’s covered lagoon

French engineer and entrepreneur François Jacques De Larderel develops a technique to collect steam from the lagoons - large ground cracks filled with boiling water seeping from hot underground rocks - through the use of a “covered lagoon”. A brick hemispheric cupola placed over the lagoon is able to capture the steam to use it as a heat source to power the boilers needed to extract boric acid from muds and slushes.

A journey through the subsoil

To build up from De Larderel’s work came the Italian engineer Vincenzo Manteri. He’s the man in charge of the first drilling operations to increase the extraction rate of steam from the subsoil.

Larderello is up and running

The Grand Duke of Tuscany - Leopold II - recognizes the merits of De Larderel and appoints him Count of Montecerboli. The burgeoning industrial complex associated with geothermal energy was then named after him to Larderello.

The heat is on

The industrial use of geothermal energy goes beyond Italy. In the American town of Boise, the first urban heating system is inaugurated.

Geothermal energy becomes electricity

Pietro Ginori Conti, General Manager of the Larderello facility in 1894, manages to turn on the first five geothermal-powered light bulbs, thanks to a contraption made up of a reciprocating engine coupled to a dynamo. 

The Italian record

The world’s first geothermal power plant goes online: Italy’s Larderello 1.

Japan, the United States, and Iceland

Italy’s example is soon followed by other countries. Japan’s first geothermal drilling is performed in 1921 near the town of Beppu. The United States follow suit in 1921 with California’s The Geysers power plant. Around 1928, Iceland starts harnessing geothermal fluids - especially hot water - to heat its households.

Destruction and reconstruction

The Larderello 2 power plant goes online. During WW2, all infrastructure in the Borax territory was destroyed. After the reconstruction period, the third power plant in Larderello becomes the world’s most powerful. Installed power reaches 127,650 kW.

Geothermal energy in the world

Geothermal energy is in full expansion mode. New Zealand opens its first geothermal power plant. Mexico follows suit the next year and many other countries go along this route.

The binary cycle breakthrough

The Soviet Union showcases its binary cycle power plant model: the geo-fluid transfers heat to a second fluid that works in a closed cycle inside the power plant, operating as a boiler. Once cooled, the geothermal fluid is re-injected in the subsoil. This technology allows generating electricity from hot rocks at lower temperatures, hence fostering the widespread use of geothermal power, albeit at lower yields. 

The Geysers are record-breaking

California’s The Geysers geothermal power plant breaks the world’s geothermal energy production record, with a total installed capacity of 2,043 MW.

Multi-purpose Geothermal energy

Geothermal energy is a renewable source with great potential and a well-established track record.  It also finds good use in heat pumps: from balneology to indoor heating, to greenhouses, aquaculture, and other industrial uses.

How geothermal energy works

Journey to the center of the Earth

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A geothermal power plant is able to harness the Earth’s heat and transform it into electricity. In some of the planet’s best-suited zones, where the Earth’s crust is thinner and jagged, this heat flow is trapped via an extraction well 3 km deep, allowing for steam to flow naturally towards the surface and the turbine.

The turbine transforms the kinetic energy of high-pressure steam in a mechanical movement which is in turn transferred to an alternator to become electricity. The electrical current is then relayed to a transformer which increases the voltage to have it grid-ready.

After being used to jump-start the turbine, steam is then channeled to a condenser (or heat exchanger), which in turn lowers its temperature and transforms it into water. Thanks to a cooling tower, temperatures are further lowered.

This is when cooled water is presented with two alternative routes: it could either be used in the condenser, where it lowers the temperature of steam, or it could be re-injected in the subsoil where it will transform in steam once again, starting off a new cycle that generates clean energy. 

Natural manifestations of geothermal energy

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Geothermal plant

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Strong points of geothermal energy

Heat becomes green energy

An incredible potential

Since 2006, a report from the Massachusetts Institute of Technology highlights how the planet’s potential for geothermal energy could provide clean energy for roughly 4000 years.

Unlimited and constant

Day, night, sun or rain: none of these conditions has any impact on geothermal operations. Hence, the Earth’s heat is always fully and readily available.

Low management costs

Once a geothermal plant goes online, its management costs are significantly lower compared to other technologies.

Did you know?

Geothermal power, culture, food, and wine: Tuscany’s winning gamble

How could a handful of hamlets perched on Tuscany’s hillsides attract over 60 thousand visitors each year, with a continuously growing trend? With a diverse and enticing cultural offer for both kids and grown-ups, excellent food and wine products, and last but not least with the highlight of geothermal vents. Larderello houses the appealing Museum of Geothermal Power, and with its 30 thousand tickets sold each year, it surely is the local highlight, while inside the Larderello 3 power plant, a concert arena was set up in 2017 to house musical and theatrical performances. The wide and varied sustainable tourism offer is completed with nature treks twisting along the Biancane di Monterotondo Marittimo and the Fumarole di Sasso Pisano natural parks.

Tuscany served tourists another tasty encore in 2009 with the world’s first Renewable-power Food community: a food farming association uniting several businesses and entrepreneurs. What do they have in common? A varied, world-class range of foodstuffs like cheese, olive oil, vegetables, beers and wines, all produced with geothermal energy.

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