Industrial Users

  • Geothermal  energy has been used in Iceland for

    Dry cod fishdrying fish for about 25 years. The main application has been the indoor drying of salted fish, cod heads, small fish, stockfish and other products. Until recently, cod heads were traditionally dried by hanging them on outdoor stock racks. Because of Iceland's variable weather conditions, indoor drying is preferred. The process is as follows: hot air is blown on the fish, and the moisture from the raw material removed. About 20 small companies dry cod heads indoors. Most of them use geothermal hot water, and one uses geothermal steam. The annual export of dried cod heads is about 15,000 tons. The product is mainly shipped to Nigeria where it is used for human consumption.

  • The diatomite plant at Lake Mývatn, near the Námafjall high temperature geothermal field, began operation in 1967, producing some 28,000 tons of diatomite filter annually for export. For environmental and marketing reasons, the plant was closed at the end of 2004. The plant employed about 50 people and was one of the world's largest industrial users of geothermal steam. The raw material was diatomaceous earth found on the bottom of Lake Mývatn. Each year the plant used some 230,000 tons of geothermal steam at 10-bar pressure (180°C), primarily for drying. This corresponds to an energy use of 444 TJ per year.
  • The seaweed manufacturer Thorverk, located at Reykhólar in West Iceland, uses geothermal heat directly in its production. The company harvests seaweed found in the waters of Breidafjördur in northwest Iceland using specially designed harvester crafts. Once landed, the seaweed is chopped and dried on a band dryer that uses large quantities of clean, dry air heated to 85°C by geothermal water in heat exchangers. The plant has been in operation since 1976, and produces between 2,000 and 4,000 tons of rockweed and kelp meal annually using 34 l/sec of 107°C water for drying. The product has been certified as organic. The plant's annual use of geothermal energy is about 150 TJ.
  • A salt production plant was  operated on the Reykjanes peninsula for a number of years. The plant produced salt from geothermal brine and seawater for the domestic fishing industry, as well as low-sodium health salt for export. During the plant's final years of operation, production was intermittent.
  • Since 1986, a facility at Hædarendi in Grímsnes, South Iceland, has produced commercially liquid carbon dioxide (CO2) from geothermal fluid. The Hædarendi geothermal field temperature is intermediate (160°C) and gas content of the fluid very high (1.4% by weight). The gas discharged by the wells is nearly pure carbon dioxide with a hydrogen sulfide concentration of only about 300 ppm. Upon flashing, the fluid from the Hædarendi wells produces large amounts of calcium carbonate scaling. Scaling in the wells is avoided by a 250 m long downhole heat exchanger made of two coaxial steel pipes. Cold water is pumped through the inner pipe and back up on the outside. Through this process, the geothermal fluid is cooled and the solubility of calcium carbonate increased sufficiently to prevent scaling. The plant uses approximately 6 l/sec of fluid and produces some 2,000 tons annually. The product is used in greenhouses, for manufacturing carbonated beverages, and in other food industries. The production is sufficient for the Icelandic market.  
  • In addition, drying pet food is a new and growing industry in Iceland with an annual production of about 500 tons. Examples of additional industrial uses of geothermal energy on a smaller scale are: retreading car tires and wool washing in Hveragerdi, curing cement blocks at Mývatn, and baking bread with steam. Iceland's total amount of geothermal energy used to process heat for industrial purposes in 2005 was estimated to be 800 TJ per year.