| Title | Nesjavellir Co-Generation Plant, Iceland. - Flow of Geothermal Steam and Non-Condensable Gases |
|---|---|
| Authors | Gestur Gislason |
| Year | 2000 |
| Conference | World Geothermal Congress |
| Keywords | Geothermal, Nesjavellir, utilisation, environmental, non-condensable gases, CHP |
| Abstract | The monitoring of steam production from the Nesjavellir geothermal field for the Nesjavellir combined heat and power plant (CHP) is carried out by recording flow rates of steam and water at various discharge points, as well as analysing the geothermal gases released into the atmosphere and shallow groundwater. Operation of the Nesjavellir power plant started in 1990. Annually 5 ñ 6 million tons of water and steam were extracted from the field, and since 1999 about 10 million tons. Initially the average enthalpy was 1700 kJ/kg, but decreased slowly to 1450 kJ/kg due to the exploitation of the field. Presently the enthalpy is rising again. Today, about 50-75% of the thermal energy of the geothermal fluids is used in the co-generation power plant to produce water for district heating and electricity generation. The main non-condensable gases in the steam are CO2 and H2S. Presently 12000 tons of CO2 and 3400 tons of H2S are discharged from the plant per annum. About 90% of the CO2 and 75% of the H2S are released to the atmosphere. Comparison with alternative energy sources shows that the geothermal power production at Nesjavellir is relatively environmentally friendly, the average mass of gases per energy unit is 7.2 g CO2/kWh and 1.3 g H2S/kWh. |