WHAT IS GEOTHERMAL?
Geothermal energy : from the earth, a renewable energy resource delivering heat and power 24 hours a day throughout the year, an energy resource nearly infinite and available all over the world.
Per definition, geothermal energy is the energy stored in form of heat below the earth’s surface. It has been used since antique times for heating, and for about 100 years also for electricity generation. Its potential is inexhaustible in human terms, comparable to that of the sun. Beside electric power generation, geothermal energy is today used for district heating, as well as for heating (and cooling) of individual buildings, including offices, shops, small residential houses, etc.
Geothermal-generated electricity was first produced at Larderello, Italy, in 1904. Iceland, Italy, Turkey, Portugal, Germany and France are the leading countries in Europe today.
The largest geothermal district heating systems within Europe can be found in the Paris and Munich area, with Austria, Hungary, Italy, Poland, Slovakia and others showing a substantial number of interesting geothermal district heating systems. Sweden, Switzerland, Germany and Austria are the leading countries in terms of market for geothermal heat pumps in Europe.
Today, geothermal power plants exist on every continent, at any place were reservoirs of steam or hot water can be found. They produce, with conventional technology, 900 MWe of electric power in the EU, around the clock. The relevant resources are far from being fully developed, also in Europe. The concept of Enhanced Geothermal Systems (including the classical Hot-Dry-Rock-idea) is going to add a tremendous increase to the potential.
The earth is full of energy. And virtually any temperature level in the underground can be used directly, for instance with deep boreholes. Did you know, that through deep boreholes almost 4500 MWth yet are installed in Europe? 4500 MWth for a clean environment. However, here again is valid: Only a small fraction of the resources are currently used.
Virtually every temperature level in the underground can be used for geothermal energy, even if this means only ca. 3-15 °C, as usual in the shallow underground in European climate. In most cases a heat pump is required here, and cooling can be supplied as well as heating. This technology provides again about 9000 MWth of heating capacity.
Croatian Center of Renewable Energy Sources (CCRES)