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Average output of high-temperature geothermal wells

9.12.2010

In 2008, 102 geothermal wells were in operation at Icelandic geothermal power plants.  The mean mass contribution from each was 0.78 million tons and the mean primary energy contribution was 1.19 PJ.

The high-temperature wells generated 5 MWe on average, based on a geothermal electricity production of 4,038 GWh in 2008.  Not all drilled wells were connected to a power plant however, as 126 wells were drilled between 1980 and 2006.  The average annual production per drilled well over this period was thus around 4 MWe. The world-average power of high-temperature wells was considered to be approximately half of this in a study conducted almost two decades ago, i.e. 2 MWe (Valgadur Stefánsson, 1992). In 2007 and 2008, 53 high-temperature wells were drilled in Iceland, mainly for new power plants that have not been started, and are thus not included.

In the accompanying graph, the wells that were operational for some part of 2008 are binned based on primary energy contribution. A third of the wells contributed 0-0.5 PJ. With increased primary energy contribution, the number of wells diminishes, as would be expected if the contributions were log-normally or exponentially distributed. These two continuous distributions, with the same mean and total number of wells are shown on the graph for comparison.  Values are rounded to the nearest integer for each bin.

number-of-wells_bins1Distribution of the primary energy contribution of wells in operation at Icelandic geothermal power plants in 2008 along with log-normal and exponential distributions with the same total number of wells. The expected value of the continuous log-normal and exponential distributions within each bin is rounded to the nearest integer.