Bjarnarflag Geothermal Power Plant by Mývatn

Construction work for the Bjarnarflag geothermal power plant is now underway. The power plant is located near Lake Myvatn and there has been discussion about the possible cooling of the groundwater system due to the operation. If this happens, this will lead to less inflow of silica rich water into the lake. Today 10 tons of silica flow into the lake every day with natural geothermal water and forms the basis for its extremely rich flora of tiny one-celled algae called diatoms.

But will the groundwater cool down? Scientists have divided opinions on this. In a report from 1999 by three specialists it is stated that the utilization of geothermal energy in the area by a 40 MW power plant will inevitably lead to a drawdown of the groundwater table and could gradually decrease or shut down the natural flow of warm groundwater from it.  In another report from 2001, also by a specialist, it is stated that the drawdown effect will be small and the probability of cooling by inflow of cold water will be negligible.

But the issue is more complicated. A third report, from yet another specialist in 1999, states that the VOLUME of the groundwater flow could diminish, leading to less Silica in Lake Myvatn.  The figure is from this last mentioned report and shows the stream of warm groundwater (as Silica concentration) from the Bjarnarflag geothermal area to Lake Myvatn.

Graphic: A drawing showing how close Bjarnarflag is to Mývatn, fram ramy.is.