Known as "The Land of Ice and Fire," Iceland is geographically gifted with an abundance of clean geothermal energy.  Shaped by the fierce divergent tectonic forces of the North American and Eurasian plates, the country has an immense degree of volcanism that brings heat and magma close to its surface.  Iceland's geothermal resources now contributes to approximately 25% of its total electricity production and over 90% of its space heating.

 

 

Geothermal Energy

Geothermal energy is power acquired from tapping into the Earth's natural internal heat sources.  This energy is found within the rocks of the Earth's crust and is derived anywhere from shallow ground all the way to magma several miles below.  These underground reservoirs of steam and hot water can be utilized to generate electricity or heat buildings.  This is primarily done by tapping steam and extremely hot water and using them to drive turbines linked to electricity generators.  

There are two principal areas for which geothermal energy is tapped:  high-temperature fields and low-temperature fields.  High-temperature areas are located within an active volcanic zone or marginal to them.  They are mostly on high ground with young, permeable rock.  Due to the topography, the groundwater table is generally deep and surface manifestations are largely steam vents.  In contrast, low-temperature areas are all located outside the volcanic zone.  The heat-source is usually from the earth's hot crust.

  Faults and fractures, which are kept open by continuous tectonic activity, provides the channel for water- often precipitation that percolates down into bedrock- to circulate through the systems and mines the heat.

There are three types of geothermal power plants:  dry steam, flash, and binary.  Dry steam is the oldest form of the three.  It takes steam out of fractures in the Earth and uses it directly to drive a turbine.  Flash plants pull deep, high-pressure hot water and mixes it with cooler, low-pressure water to also create steam to move turbines.  Binary, which are expected to become the primary form of geothermal energy production, passes hot water through a secondary fluid with a much lower boiling point than water.  This causes the secondary fluid to turn to vapor, which then drives a turbine.  

Binary plants release essentially no emissions and geothermal fields in general, produce only about 1/6th of the carbon dioxide that a relatively clean natural-gas-fueled power plants produces.  Also, unlike other forms of renewable energy, such as solar and wind, geothermal energy is always available.  It is relatively inexpensive, with savings from direct usage reaching as high as 80% over fossil fuels.  

Geothermal power generation is not perfect, however.  One concern regards the disposal of some of the geothermal fluids, which may contain low levels of toxic materials.  Also, even though geothermal sites are available 365 days-a-year and capable of providing heat for several decades, the specific locations do sometimes cool down, rendering it less productive.

 

History of Geothermal Energy in Iceland

Although geothermal energy have been used in Iceland for over a century, it wasn't until the 1940s that it was heavily industrialized.  Prior to that time, geothermal water and heat was primarily used within domestic households by individuals, who would use it for bathing, laundry, cooking, and heating if pipes were installed. 

During World War II, Iceland became an important strategic location for Allies.  Due to presence of British and American troops, the Icelandic economy experienced rapid growth.  With an incoming abundance of foreign revenues, the capital city of Reykjavik slowly invested in its geothermal district heating system.  

The country itself would further expand its geothermal infrastructure by developing five major power plants to harness the Earth's power.  The most crucial of the five is the Nesjavellir Power Plant, located on the northeast side of the Hengill volcano.  The water from the site travels through a 16.78 mile pipeline to the Greater Reykjavik area, supplying the municipality with space heating and hot water.  It is the most powerful geothermal well in the world.   

 

Geothermal Uses in Iceland

Geothermal energy in Iceland is used in a variety of ways, including space heating, swimming pools, fish farming, industry, snow-melting, and greenhouse farming.

There are about 169 recreational swimming centers in Iceland, with 138 of them using geothermal heat, not counting natural hot springs, nature baths, or heated beaches. Swimming is very popular in the country.  In Reykjavik alone, there are 17 public swimming pools.  Also, just 24 miles outside of the capital is the world's most famous hot spring, The Blue Lagoon, which is also heated using geothermal means.  The lagoon is man-made and is fed by superheated water from the nearby Svartsengi plant.  Due to its high mineral concentration, the water in the Blue Lagoon cannot be recycled and must be disposed of every two days into the nearby landscape, a permeable lava field 50 cm to 1 meter thick.  The natural silicate in the water is the primary agent in giving the lagoon's famous milky blue shade.  The Blue Lagoon is country's number one tourist attraction.

Fish farming has become profitable in Iceland. There are about 50 plants in the country, producing approximately 6,200 tons of fish annually.  Salmon is the most important species, accounting for about 70% of the production, with arctic char, trout, halibut, and cod making up the remaining 30%.  Geothermal water, commonly at 68-122°F, is used to heat the fresh water.

Geothermal snow melting infrastructure have expanded rapidly in Iceland in the past two decades.  Now, most new car parking areas and sidewalks in the region are built with a melting system.  Geothermal water from space heating returns at 95°F and is commonly recycled to perform the de-icing. Often if the load is high, the returning water will be mixed with incoming hot water at 176°F to perform intense snow melt.  In downtown Reykjavik, a snow-melting system has been installed to cover an area of over 50,000m².  The country's total snow melting system is at approximately 920,000m², of which about 690,000m² are in Reykjavik proper.  The distribution of the infrastructure is spread: 1/3 in commercial areas, 1/3 in public areas, and 1/3 by private homes.  

Due to Iceland's high latitude and short growing season, greenhouses have become a crucial part of Icelandic agricultural life.  Heating these greenhouses with geothermal energy began in the country in 1924.  Geothermal steam is commonly used to boil and disinfect the soil, while geothermal produced CO₂ is commonly used to enrich plants.  Greenhouse production is divided between vegetables (approximately 50%), cutflowers (26%), and potplants (24%) for the domestic market.  The total greenhouse area in Iceland is around 194,000m².