The energy resources of Iceland, the hydro and geothermal reserves, are vast in relation to the size and population of the country. Harnessable electrical power from rivers and geothermal sources in Iceland is estimated to be no less than 50 TWh per annum taking into account economic and ecological considerations. This estimate is, however, rather conservative and assumes 30 TWh per annum from hydro and 20 TWh per annum from geothermal sources. 
The present use of electrical energy in Iceland is approximately 4.5 TWh per annum, so that some 9% of the minimum potential has been harnessed so far.
Most of the hydro power plants are owned by Landsvirkjun (the National Power Company) which is the prime supplier of electricity in Iceland. Its direct sales to energy-intensive industries amounted to 2.1 TWh in 1992.
Hot water and natural steam are extensively used for the heating of buildings and greenhouses. About 85% of all houses are heated with geothermal energy. In industry, the main use of geothermal heat is for the drying of seaweed, diatomite and salt, but research is ongoing to being carried out to develop new industrial uses for natural steam.
1) Share of Total Primary Energy Supply in 2003
2) Breakdown of Sectorial Final Consumption by Source in 1973 and 2003
