Geothermal Energy in Iceland

November 28, 2018

Patti_geothermal_DSC05721 (1) Patti_geothermal_DSC05761 (1) 
Photographer: Patti Weeks
Summary Author: Patti Weeks

The Nesjavellir Geothermal Power Plant is the second largest of five geothermal plants in southwest Iceland. It's situated on the active Hengill volcano area, which lies on the Mid-Atlantic Ridge — the tectonic plate ridge that splits the Earth’s crust virtually the entire length of the Atlantic Ocean. The active volcanic belt running southwest to northeast through the center of Iceland, known as the Reykjanes Ridge, separates the North American and Eurasian tectonic plates, diverging at the rate of nearly an inch (2 cm) per year.

Rainwater seeps deep into the Earth and is heated by magma within volcanic faults and fissures. Wells or boreholes, which can be up to several miles deep, are drilled to extract the heated water. Along with steam emitted from the fissures, this mineral-rich water is utilized by geothermal energy plants to heat fresh water. High-pressure steam is used for electricity, and low-pressure steam and separated water are used for heating fresh groundwater, to heat the Reykjavik region. The plant’s turbines (seen in the top photo at bottom) separate the hot water and steam. This plant produces 120 MWe (megawatts electric) of power and about 475 gal (1800 l) of water per second.

Geothermal energy from the Nesjavellir Geothermal Power Plant, along with other nearby plants, meets the heating and hot water needs for the Greater Reykjavik Capital Region and its six surrounding municipalities, serving a total population of over 220,000 or 67 percent of Iceland’s population. Water leaves the plant at the temperature of 185 F (85 C) at the beginning of its approximate 7 hour, 16.7 m (27 km) westward trek to Reykjavik through a mostly above-ground insulated steel pipeline. The piping only loses about 3-4 F (2 C) of heat by the time it reaches the city. Note that both the pipeline and city of Reykjavik (in the distance) are seen in the lower photo.

As of 2003, approximately 98 percent of the Greater Reykjavik area was receiving its heating from geothermal sources. Before 1940, the region’s air was often filled with black clouds of smoke from the burning of imported fossil fuels. As reported in 2011, the reduction in CO2 emissions ranged from 2.5 to 4 million tons annually. Reykjavik is now one of the cleanest cities in the world. Photos taken on September 11, 2018.

Photo Details: SONY DSC-HX400V camera; 16.71 mm focal length; 1/640 second exposure; f/4 aperture; ISO 80. Second photo same except 13.76 mm focal length; f/3.5 aperture; ISO 160.