TO Boast, near Helsinki, in Finlanda geothermal deposit has recently been identified where the internal heat of the earth will be able to provide geothermal energy for well 20 million years. With this discovery, the country’s carbon dioxide emissions could be reset by 2030 With the aim of achieving carbon neutrality. The deposit will be used both to produce electricity and for heating buildings thanks to a geothermal heating systemthe first of Finland, which it produces 35 times more heat than a traditional system. Together with the geothermal plant, in Vantaa it is being built The largest thermal energy storage system in the worldwhich will enter into operation in 2028. His name is Varanto (which in Finn means “reserve”) and is a project by the Vantaa Energy company. The storage tank will consist of Three huge artificial cavesfor a total volume of 1,100,000 m3where very hot water will be accumulated, whose thermal energy can be kept for months.
The Geothermal Heating System of Vantaa in Finland
In the rocks of the earth’s crust, the temperature increases with the depth of about 3 ° C per 100 m. Starting from 20 m deep, it is no longer conditioned by the air temperature, but becomes stable throughout the year. This means that the subsoil is warmer than the air during the winter and colder in the summer: this allows you to carry out a heat exchange between subsoil and surface in order to heat the buildings. In particular, a “geothermal deposit“, That is, an area within which the heat available in the rocks is greater because of its geological characteristics.
Normally, to exploit the internal heat of the earth, well wells are not more than 400 me, for this reason we speak of surface geothermal energy. In Finland, however, the exploit is exploitedmedium-southern geothermal energythanks to the most modern technologies that have made it possible to dig Three wells 800 m long. The wells capture the heat by introducing cold water through a subsoil, which heats up in depth and then returns to the surface. Here the water can be used to rotate the turbines of a generator that produces electricity or be distributed through a network of pipes up to the buildings, with the aim of heating them (district heating). The Finnish plant has a production capacity of 2,600 MW per yearsufficient to heat about 130 private homes.
The largest thermal energy storage system in the world
In addition to the heating system, in Vantaa it is under construction The largest thermal energy storage system in the world. For the purpose they will be used Three artificial caves About 20 m wide, 300 mi long 40 high, the bottom of which will be 100 m deep. Their volume overall it will be well 1,100,000 m3. There total capacity for the accumulation of thermal energy of the plant will instead be of 90 Gigawattara (GWH)which is equivalent to 1.3 million batteries for electric cars. The caves will be filled with water which in the summer will be heated using different sources of renewable energy and which thanks to the regulation of the internal pressure can reach one temperature of 140 ° C without evaporating. The water will remain thus stored for months and in winter it will be used for heating.
In general, thanks to this project, it is planning to reduce carbon dioxide emissions up to zero by 2030. Furthermore, it could constitute an inspiration for other countries, pushing them to invest in similar technologies to exploit geothermal energy, which is Much more “stable” than other renewable sources such as solar and wind, conditioned by the seasons and the weather.
