Industrial tours

Tuscany is an historic area in the West of Italy, between the Ligurian and the Tyrrhenian Seas and the Apuan Alps (Alpi Apuane). The cultural heritage of Tuscany is daunting. It is the birthplace of Dante and Petrarch, Michelangelo and Leonardo da Vinci, Puccini and Mascagni. This region has accumulated many fine architectural sites and pieces of artwork. Who doesn’t know the silhouettes of the Cathedral of Florence or Pisa, the Uffizi Gallery and the statue of David? Tuscany landscapes also stun with their diversity and sated colours. Haunting Mediterranean sights from the top of Monte Argentario in the South or the Marble Mountains of Carrara in the North, vineyards of Brunello and Chianti on the way from Florence to Grosseto, town towers and cathedrals of Siena or Pienza on Tuscan hills. For millions of tourists  Tuscany is the best place for recreation and travelling, the place where you can feel the breath of history and world culture. But hardly anybody knows the names of two of Tuscany’s outstanding figures – Francesco de Larderel and Prince Piero Ginori Conti, yet they are the ones who founded an important modern industrial field – geothermal energy. 105 years ago, in 1913, Tuscany was the place where the first world’s natural steam driven power station was put into operation by Prince Conti.
Geothermal resources are generated by water superheating in underground reservoirs near the surface by the heat produced by molten rocks (magma), located deep beneath the ground. Heat flow intensity within the ground depends on magma properties and the geological condition of the Earth’s crust. In the regions of high geothermal activity magma often rises to the surface much closer than in others, and the converging boundaries of large tectonic plates pass over each other making the near-surface layer more permeable. This is why these regions practically line up with territories of high seismic and volcanic activity. Such regions include Tuscany.

Mankind has been using natural heat that sometimes autonomously rises to the surface as superheated steam since ancient times. For instance, in Tuscany the Romans actively tapped natural thermal springs. One of these natural springs is located in Saturnia, in the province of Grosseto. However, it took many years before natural heat could be used in technological processes. Superheated steam, which rises to the Earth’s surface, often contains different chemical elements or their compounds. The most well-known substance among these is hydrogen sulphide. That is why many natural thermal springs are hydrosulphuric.
Tuscan geothermal sources also contain many other valuable components, such as Boron, so in the early 19^th century Tuscany was a large producer of Boron and its compounds. In extracting this commercial product not only was the natural discharge of steam utilized here, but also shallow wells. The owner of this chemical facility was a French engineer and businessman Francesco de Larderel who had settled in Tuscany. The extraction of Boron out of warm water was performed via steaming and this required an enormous amount of wood fuel, resulting in the deforestation of the surrounding forests. The business output did not satisfy the owner, Francesco de Larderel, and he developed processes of natural heat utilization and its usage instead of wood fuel. Later, thanks to Larderel, natural steam energy started to be used in machines – lifting devices, pumps, transport carriers, etc. Larderel’s efforts were repaid; his company became a European monopoly in boron production, he assumed the title of Count, and a small local town in Tuscany was named after him, where the centre of geothermal technologies was established – Larderello. This unique place bordering three Tuscan provinces – Pisa, Grosseto and Siena, is today considered to be the homeland of geothermal energy. Francesco de Larderel could certainly be called a pioneer of “green”, environment-friendly renewable technology, caring for nature.
However, that was not the end of the story. In the early 20th century the people of Larderello grew so familiar to the utilization of natural steam that they started using it to heat their homes, greenhouses and amenities. 1904 was a big year for the Florentine, Piero Ginori Conti, Prince of Trevignano, who was head of a boric acid production firm. To produce electricity and lighting he connected five bulbs, an electric device and an engine, a working fluid, where (clean water) was heated in a heat-exchanger, fed with superheated natural steam. This was the first time this had been performed and in doing so he applied a prototype of a modern binary system in his design.  Thus, a new area of technology – geothermal power – was founded, and, in 1913 the world’s first commercial geothermal power plant began to operate here. Nowadays, the total power capacity of geothermal plants in Larderello, led by Enel Green Power, is around 600 MW, and in Italy 34 geothermal plants generate over 5 mlrd kWh electric power in total, satisfying more than 25% of  energy demand in Tuscany or providing about 2 million of Italian families with electric power. Furthermore, geothermal heat is supplied to several thousands of standalone and industrial facilities and 25 hectares of greenhouses. The total area of geothermal fields in Tuscany is around 400 km². Italy takes fifth place in the world in the production of electricity from geothermal sources, and Tuscany produces more than the whole of Iceland with its renowned geysers. It should be noted that today the majority of geothermal plants work on dry steam, when it is supplied directly to a steam turbine.
Thus, in the USA, which is the top producer of electric power from geothermal energy, approximately one half is generated this way. Nevertheless, steam must have sufficient pressure, temperature and pureness, which is not always possible. This is the reason why usage of binary systems is the most promising trend (the process Piero Ginori Conti initiated), where the energy of natural steam via a heat-exchanger is transferred with the help of a special working fluid, which is also converted into steam and rotates a turbine with a generator connected to it. In this case, formulation of the working fluid with boiling temperatures lower than for water makes it possible to use practically any kind of natural steam. Another important feature of modern geothermal technologies is to maintain a constant ground water level in underground water reservoirs, because in the course of time this can deplete due to the active use of natural steam. To avoid this, spent low pressure steam is forced back into subsurface layers through injection wells. One more modern trend is the drilling of deeper geothermal wells in locations with superheated steam reservoirs featuring higher pressure and temperature. For instance, in Tuscany natural steam most commonly has a temperature of between 150^оC - 270^оC and a pressure of 2 MPa, but the steam recovered from depths 3000 m – 4000 m has the pressure of 6-7 MPa and the temperature of 300^оC - 350^оC. For good reason the caloric value of such steam is essentially higher.

All the areas discussed above are being actively developed by the company Enel Green Power, not only in Italy, but also in other countries of the world, including Central and South America.
But let’s get to the point! If you are lucky enough to visit Tuscany and have a chance to travel around by car, take the time and visit Larderello. Wherever you may drive from – Florence or Siena, Pisa or Grosseto, you will experience memorable impressions. You will be followed by marvellous landscapes with thick forests and vineyards, little villages looking like historic  exhibits, and small, inexpensive places to eat. Eventually, upon entering Larderello you will see the extraordinary sight of Tuscan nature being hugged by industrial infrastructure. This is the living homeland of geothermal energy. And, be sure to visit the local museum of geothermal energy - Geomuseo. Here you will learn much more than in this short story, and we hope that you will be very pleased.