The energy of geothermal reserves possessed by Russia is 10-12 times higher than the potentials of organic fuel.
In the long view, this will foster the effective use of the Earth energy for heat supply over 70-80 % of the Russian territories. The greatest geothermal reserves are found in the Chukotka region, Kurily Islands, Far East of Russia, West Siberia.
Nowadays the geothermal deposits are found and explored in 80 countries, and 58 of these are making good use of the Earth energy. The Russian share in the worldwide output of this energy now ampunts to 10%, although could be much more.
Exploiting of geothermal deposits
- The low-temperature heat-carrier is used only straightforwardly in the heat pumps, communal and hothouse services and in balneology.
- The intermediate-temperature and high-temperature heat-carriers can be used not only straightforwardly but also for power generation.
- Exploitation of the deposits containing the natural heat-carrier with temperature above 200° is realized by geothermal power plants of direct action. In this case the heat-carrier is a working fluid.
- Exploitation of the deposits containing the natural heat-carrier with temperature 100° and higher is realized by binary geothermal power plants. The heat-carrier transfers a part of its heat to the working fluid, the steams of which are generating the electric energy.
Classification of geothermal deposits
By their productivity the geothermal deposits are classified as
- low-yield - productivity of a single well is less than 1000 ton per day
- medium-yield - productivity of a single well is 1000-3000 ton per day
- high-yield - productivity of a single well is more that 3000 ton per day
By the excessive pressure value the geothermal deposits are classified as
- low-lift - excessive pressure is lower than 0.2 MPa;
- medium-lift - excessive pressure is 0.2 - 1 MPa;
- high-lift - excessive pressure is higher than 1 MPa
By the heat-and-power capacity the geothermal deposits are classified as
- low heat-and-power capacity - less than 0.01 GJ/s
- medium heat-and-power capacity - 0.01 - 0.05 GJ/s
- high heat-and-power capacity - 0.05-0.1 GJ/s
- ultrahigh heat-and-power capacity - higher than 0.1 GJ/s
By the temperature in the borehole mouth the geothermal deposits are classified as
- low-temperature - below 100°C
- mid-temperature - 100-150°C
- high-temperature - above 150°C
Expenses and risks concerned with extraction of geothermal sources:
Temperature dependence of the water resistivity at positive t° takes the form
where t° is resistivity of the solution at temperature t°C,
ρ18 is resistivity of the solution at temperature 18°C,
β is temperature coefficient that equals to 0.026 for water solutions of NaCl within temperature interval 0-50°C