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Preparing for WGC 2020 – Iceland’s geothermal resources & potential

Strokkur at the Geysir, Iceland (source: Emil Kepko (c) CC BY 2.0)
Alexander Richter 11 Feb 2020

Iceland, sitting on the on the major fault lines of the Mid-Atlantic ridge, is blessed with an abundance of geothermal resources and potential, yet only taps a fraction of it with current utilisation.

In April 2014, ThinkGeoEnergy published its second Geothermal Magazine … and unfortunately its last. The goal was to provide a high-profile, glossy and international magazine to the geothermal world based on the same focus and view on the geothermal world as our website.

That edition of 2014 provided a country focus on Iceland and we thought it would be time to republish the content shared then ahead of the World Geothermal Congress taking place in Iceland, April 27 to May 1, 2020.

So here an article on the geothermal resources and potential in the country of Iceland, written by Gudni Axelsson, then Chief Geophycisist of Iceland GeoSurvey (ÍSOR), now Director of the GRÓ Geothermal Training Program in Iceland (formerly UNU GTP). The text includes a few updates due to plant additions in Iceland since 2014).

The location of Iceland on the major fault lines of the Mid-Atlantic ridge not only provides for breath-taking scenery, but also for a unique geology and geothermal resources. The Eurasian and North American plates are diverging by about 2 cm per year, as is visible above sea level in the country, which makes Iceland one of the most tectonically active places on earth. The geothermal resources stem from the unusually high magma- and heat-flow from the Earth’s mantle and tectonic activity, both associated with the interaction of the Atlantic spreading ridge and a mantle hot-spot. Figure 1 (Source: modified from Pálmason et.al. 1985 & Bodvarsson 1982) shows a simplified sketch of the geothermal resources of Iceland, with numerical estimates of their size, both the terrestrial energy current and the vast amount of heat stored in the crust.

Figure 1: This graphic shows the size of geothermal resources in Iceland, with numerical estimates of both the terrestrial energy current and the vast amount of heat stored in the crust. Modified graphic from Pálmason et.al. 1985 & Bodvarsson 1982.

Figure 2 shows a map of the distribution of geothermal systems in Iceland, which are classified as either high-temperature (above 200 degrees Celsius at 1 km depth) or low-temperature (below 150 degrees Celsius 1 km depth). About 25 high-temperature systems have been identified, all within the volcanic zone passing through the island. The heat-sources of these are believed to be cooling magma bodies at depth. Conversely about 250 low-temperature systems are found all over the island, almost exclusively outside the volcanic zone. The heat-source of the low-temperature activity is believed to be the abnormally hot, and tectonically active, crust.

Figure 2: Geothermal Map of Iceland Source: Simplified geothermal map of Iceland, ÍSOR
Figure 2: Geothermal Map of Iceland Source: Simplified geothermal map of Iceland, ÍSOR

 

Geothermal Systems overview (Picture: ISOR via UNU-GTP)
Geothermal Systems overview (Picture: ISOR via UNU-GTP)

 

The current utilization is, however, only a fraction of the estimated potential of Icelandic geothermal resources. This can e.g. be seen in Table 1, which lists most known high-temperature geothermal systems and their estimated electrical generation potential as well as the installed capacity of the geothermal power-plants in operation, for comparison. The table derives from work on the Master Plan on Energy Development in Iceland (Rammaáætlun) during which estimates of the potential for electrical power generation from geothermal resources from 1985 were revised to provide a new estimate range for most of the known high-temperature geothermal systems. The range given provides an overall estimate ranging from 2,550 to 7,660 MWe, for these particular systems. Current installed electrical generation capacity amounts to 755 MWe (in 2014 it was 662 MWe), mostly in the South-west corner of the country and in end of the volcanic belt in the North-east, as the main interior of the country is not settled and not easily accessible.

Table 1: known high-temperature systems and their estimated potential and compares them to the installed capacity. (source: work on the Icelandic Energy Development Master Plan, Rammaáætlun)
Table 1: known high-temperature systems and their estimated potential and compares them to the installed capacity. (source: work on the Icelandic Energy Development Master Plan, Rammaáætlun)

In addition to electrical generation, direct geothermal energy use, mainly for space-heating, is extremely important in Iceland. It actually accounts for a larger share of the geothermal utilization than electricity generation, or almost 26 PJ (1 PJ = 1015 J) in 2011, or 7,200 GWh. In comparison generation of geothermal electricity amounted to 4,700 GWh that same year.

Further geothermal exploration, with exploration drilling, advances in understanding of the resources, technical advances concerning drilling and utilization, resolving of environmental issues, application of EGS-technology and deep drilling are among the issues that need to be resolved and/or advanced before major additions to geothermal utilization in Iceland are established.

Table 1: Estimated electrical generation potential of most known high-temperature geothermal fields in Iceland for 50 years (Orkustofnun and ÍSOR, 2009). Current installed capacity shown for comparison.