Landsvirkjun is committed to utilising natural resources in the most efficient manner and to reduce the emission of pollutants into the environment. Landsvirkjun operates two geothermal power stations in the northeast of Iceland, at Krafla and Bjarnarflag.
The Company also conducts geothermal research pertaining to the proposed power station at Þeistareykir, the expansion of Krafla and proposed power station projects at Bjarnarflag and Hágöngur. Monitoring on the effects of run-off water from the stations and on the potential effects of geothermal research is carried out on an annual basis.
Surface discharge at geothermal stations
In 2014, Landsvirkjun re-injected more than 90% of the separated water from its geothermal stations or approximately 4,296,000 tonnes.
Run-off water (condensate and separated water) contains heavy metals and nutrients which mostly originate from geothermal fluid. They are also present as a result of the corrosion of equipment. The natural concentration of these chemicals varies between areas and is, amongst other things, reliant on the chemical composition of groundwater and volcanic activity. If concentration levels are too high then surface discharge can affect the ecosystem. These environmental effects can be reduced by re-injecting run-off water into the geothermal reservoir. However, surface disposal is sometimes necessary. Monitoring surface discharge and its potential effects on groundwater and the ecosystem is therefore essential.
Separated water at the Krafla Geothermal Station is partly re-injected back into the geothermal reservoir. The objective of re-injection is to keep up the pressure levels in the geothermal system, therefore reducing the environmental impact. Separated water from the Bjarnarflag Geothermal Station is disposed of at the surface into the Bjarnarflag Reservoir and is channelled into the groundwater via a fissure in the western end of the reservoir. The chemical composition of the geothermal fluid is measured annually in all boreholes and in certain areas in the processing cycle.
Re-injection keeps up the pressure levels in the geothermal system, therefore reducing environmental impact.
Discharge water from the wells at Þeistareykir is channeled into nearby lagoons and then flows into a fissure or shallow well. The discharge will be re-injected into special re-injection wells, at a depth of 250- 450 metres once the Power station is in operation.
There was no discharge from the proposed utilisation area at Bjarnarflag and Hágöngur this year. More information of re-injection measures at geothermal stations in the last five years can be found in the numerical data section.
Monitoring on groundwater in Þeistareykir and the Kelduhverfi area began in 2007 in order to gather baseline information for the proposed geothermal station at Þeistareykir. The chemical composition of water under natural conditions and before utilisation can be analysed with this information. Continuous monitoring enables us to monitor the potential impact of geothermal research in the area and energy utilisation later on. Further information on environmental monitoring can be accessed in the chapter on Þeistareykir.
Main results on groundwater monitoring in Þeistareykir and the Kelduhverfi area 2014:
- The concentration of arsenic was below environmental limit 1 at the monitoring stations in Þeistareykir and Kelduhverfi area.
- The concentration of aluminium was well below the Norwegian Environmental Limit 1 at monitoring stations in Þeistareykir and Kelduhverfi area. The Norwegian limits are used as Iceland has not identified or outlined set limits with regard to aluminium levels.
- The concentration of mercury is under or at the detection limit and well within environmental limits at all monitoring stations.
- Geothermal effects can be identified in some groundwater sampling areas at Þeistareykir; cold groundwater in the area contains substances that can be traced to natural geothermal reservoirs in the area.
Groundwater by Mývatn
Groundwater research by Mývatn shows that the inflow at Mývatn is mostly groundwater which flows from all directions until it reaches the lake. The flow is mostly from the southern end and part of the groundwater is heated up by the geothermal system in the Námafjall Mountain, mixing with geothermal water from this source and from Krafla. Groundwater monitoring stations were increased by Mývatn in 2014 as a result of the decision to re-assess the groundwater model for the area. The reassessment of the model will offer a better picture of the flow patterns of discharge water from the power station areas.
Location of power stations and sampling points
The effects of effluent water from the Krafla and Bjarnarflag stations are closely monitored.