frazione
A ''frazione'' (plural: ) is a type of subdivision of a ''comune'' (municipality) in Italy, often a small village or hamlet outside the main town. Most ''frazioni'' were created during the Fascist era (1922–1943) as a way to consolidate territ ...
'' of the ''
comune
The (; plural: ) is a local administrative division of Italy, roughly equivalent to a township or municipality. It is the third-level administrative division of Italy, after regions ('' regioni'') and provinces (''province''). The can also ...
'' of
Pomarance
Pomarance is a ''comune'' (municipality) in the Province of Pisa in the Italian region Tuscany, located about southwest of Florence and about 60 km southeast of Pisa.
Pomarance borders the following municipalities: Casole d'Elsa, Castelnuovo ...
, in
Tuscany
Tuscany ( ; it, Toscana ) is a Regions of Italy, region in central Italy with an area of about and a population of about 3.8 million inhabitants. The regional capital is Florence (''Firenze'').
Tuscany is known for its landscapes, history, art ...
in central
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
The region of Lardarello has experienced occasional
phreatic eruption
A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground water or surface water. The extreme temperature of the magma (anywhere from ) causes near-instantaneous evapo ...
s, caused by explosive outbursts of steam trapped below the surface. The water is contained in
metamorphic rocks
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
where it is turned to steam which is then trapped beneath a dome of impermeable shales and clay. The steam escapes through faults in the dome and forces its way out in the hot springs. It possesses a dozen explosion craters 30–250 m in diameter. The largest is the
Lago Vecchienna __NOTOC__
Lago, which means "lake" in Italian, Portuguese, Spanish and Galician, may refer to:
Places
*Lago, Calabria, a ''comune'' in the Province of Cosenza, Italy
*Lago, Mexico, a municipality zone in the State of Mexico
*Lago District, a ''dis ...
crater which last erupted around 1282, now filled by the Boracifero Lake.
Larderello now produces 10% of the world's entire supply of
geothermal electricity
Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 26 ...
, amounting to 4,800 GWh per year and powering about a million Italian households. Its geology makes it uniquely conducive to geothermal power production, with hot
granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
rocks lying unusually close to the surface, producing steam as hot as 202 °C (396 °F).
Contrary to popular belief, Larderello is not a
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are ...
as no eruptions of
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
had occurred there at any point in history.
History
The region was known from ancient times for its exceptionally hot springs. The
Romans
Roman or Romans most often refers to:
*Rome, the capital city of Italy
* Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a lette ...
used its
sulphur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
springs for bathing.
During the 19th century it became one of the first places in the world where geothermal energy was exploited to support industry. In 1827, François Jacques de Larderel, a
Frenchman
The French people (french: Français) are an ethnic group and nation primarily located in Western Europe that share a common French culture, history, and language, identified with the country of France.
The French people, especially th ...
, invented a way of extracting
boric acid
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves ...
from the mud by using steam to heat cauldrons to separate the two.
Leopold II, Grand Duke of Tuscany
Leopold II( it, Leopoldo Giovanni Giuseppe Francesco Ferdinando Carlo, german: Leopold Johann Joseph Franz Ferdinand Karl, English: ''Leopold John Joseph Francis Ferdinand Charles''. (3 October 1797 – 29 January 1870) was Grand Duke of Tusc ...
was an enthusiastic supporter of Larderel's scheme and awarded him the title of Count of
geothermal power
Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 2 ...
.
Prince Piero Ginori Conti tested the first geothermal power generator on 4 July 1904, at the Larderello dry steam field in Italy. It was a small generator that lit four light bulbs. In 1911, the world's first geothermal power plant was built in the Valle del Diavolo ("Devil's Valley"), named for the boiling water that rises there. It was the world's only industrial producer of geothermal electricity until 1958, when
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
built a plant of its own in
Wairakei
Wairakei is a small settlement, and geothermal area a few kilometres north of Taupō, in the centre of the North Island of New Zealand, on the Waikato River. It is part of the Taupō Volcanic Zone and features several natural geysers, hot pool ...
. In recent years concerns have been expressed about the sustainability of its steam supply, as a 30% drop in steam pressure levels has been recorded from the maximum levels of the 1950s.