Idaho began tapping its vast geothermal energy supplies as far back as 1892 to supply district heating to its capital city, Boise. A century later Idaho had no operating geothermal plants because readily available inexpensive hydro power resources made new commercial geothermal projects difficult to justify, even if the fuel is essentially free.
U.S. Geothermal Inc. (USG) is close to breaking that long dry spell with commercial operation of the first phase of its new and improved Raft River Geothermal Project. The plant is located in the Raft River region of southern Idaho, approximately 200 miles southeast of Boise (Figure 1).
1. Do you know the way? U.S. Geothermal bought the assets of the defunct DOE geothermal demonstration plant in Idaho, renovated the wells, and will have a new 13-MW plant on-line this year. Courtesy: U.S. Geothermal
The Raft River site is located in what is by far the most studied region for geothermal resources in the state. The Idaho National Laboratory began research in 1975 on regional geothermal resources and characterization of the various geothermal fields in the Snake River plain in Cassia County. A 1985 study commissioned by the Bonneville Power Administration confirmed that the Raft River area ranked first in the “Final High Temperature Ranking: Pacific Northwest” for sites in the four-state region. Subsequent studies confirmed the site has a 50% probability of producing 15.6 MW per square mile.
The DOE began construction of the world’s first commercial-scale binary geothermal power plant at the same site in early 1980. That demonstration plant operated from the fall of 1981 until June of 1982 and produced a net output of 4 MW. Five production wells and two reinjection wells were drilled to depths of from 4,500 feet to 6,000 feet. Geothermal fluid temperatures ranged from 275F to 300F (Figure 2).
2. Deep impact. Raft River geothermal resources average around 280F and may hold enough energy to produce over 100 MW. The reservoir model found the field’s natural recharge capability is 405 gpm of 312F water. Courtesy: U.S. Geothermal
By mid-1982 the DOE changed its priorities on geothermal research and decided to privatize future geothermal development—government jargon meaning that the commercial price of geothermal power was way too high. So the DOE declared victory at the $40 million Raft River demonstration plant, sold off the pumps and electrical equipment, and packed up and shipped the plant equipment to another geothermal project in Nevada. Only the capped wells and a maintenance building remained when the geothermal garage sale was over and the doors were locked. The site remained untouched for the next 20 years.
Email
Comments
Print
Reuse
Comments (1)
I would thank you for your article, it is very exhaustive and complete. I am an Italian student from Florence University and I would ask you if you can give me some specifications about Raft River plant, in particular about the type of the heat exchanger used. Thanking for your consideration and your time
Best regards
Noemi Silicato