Noise is mostly generated by the equipment and machinery used for geothermal utilisation as well as the noise from active wells. Landsvirkjun closely monitors its geothermal operations to ensure that noise levels remain within the legal requirements.
Noise levels under the legal requirements
Noise is defined as an undesirable sound from e.g. anthropogenic sources, traffic or industrial activities. Sound intensity is measured in decibels (dB) or decibels A (dB (A)) which simulates the sense of the human ear. The operational areas at Krafla and Bjarnarflag, where geothermal electricity generation takes place, are zoned as industrial areas. The Icelandic regulation on noise specifies a reference limit for industrial zones of 70 dB (A) at site boundary. Landsvirkjun has set strong reference limits for popular tourist destinations within the industrial zones at Lake Mývatn, ensuring that sound levels do not exceed 50 dB (A) in these areas which is the reference equivalent sound level value for residential areas. No reference values exist for recreational areas.
Landsvirkjun has set strong reference limits for popular tourist destinations within the industrial zones at Lake Mývatn.
Turbine generator units and the release of steam during the capacity evaluations of the boreholes, at geothermal power stations, are the main source of noise. The sound level at each time therefore depends upon the number of boreholes being flow tested, the number of turbine generator units in operation, as well as weather conditions. Annual measurements of the noise levels from the geothermal power stations are conducted at defined measurement locations. Additionally, measurements are conducted at boreholes when capacity evaluations take place. Mufflers are installed at all borehole sites.
Noise intensity in decibels (dB) measured during various human activities
Mývatn area: Industrial areas (dark grey) by the Krafla Geothermal Power Station and the Bjarnarflag Geothermal Power Station
Noise level measurements
Krafla Geothermal Power Station area
Noise level measurements were conducted at Krafla on the 3rd of October, 2013. There was rainfall and a north-easterly wind (2 m/s) on the day of data collection and the temperature was 2°C. Both generating units were active during data collection and three boreholes were active. The noise levels in tourist areas and the monitoring stations outside the industrial area were below the 50 dB reference levels set out by Landsvirkjun. More details on measured equivalent-noise in the Krafla area between 2009 and 2013 and information on special circumstances pertaining to the measurement process in 2013 can be found in the numerical data section.
Bjarnarflag Geothermal Power Station area
Noise level measurements were carried out at the Bjarnarflag Geothermal Station on the 3rd of October,2013 and the Station’s steam generator units were in operation. Noise levels at monitoring station 26 (information lot – close to old bathing area) were above 50 dB; similar to that of the previous three years. This could, amongst other things, be due to noise carrying from the separating station, in close proximity to the area. More detailed information on measured sound levels, as well as any special circumstances, at Bjarnarflag station between 2009 and 2013 can be found in the numerical data section.
The location of the noise monitoring stations at Krafla and Bjarnarflag
A five year research project was launched this year on noise levels at the Krafla Geothermal Station and at the potential power project sites at Bjarnarflag and Þeistareykir. Three continuous monitoring stations will be set up during the summer of 2014, measuring noise levels at all three locations. Weather monitoring stations have been set up as precise meteorological data is important for noise level monitoring.