From Open Energy Information
Roosevelt Hot Springs is among the hottest and best documented of the geothermal resources in the Basin and Range Province. The field is located on the eastern edge of the Province in south central Utah, on the western margin of the Mineral Mountains, approximately 15 miles northeast of the town of Milford and about 165 miles south of Salt Lake City. Blundell Plant 1, a 26 megawatt (MW) installed-capacity single-flash unit was completed in 1984. The project earned the U.S. Department of Energy’s innovation award in 1984 for being the first commercially-produced geothermal power plant outside of California. In 2007, Blundell 2, an 11 MW binary bottoming-cycle unit was brought on-line. The geothermal fluid for both plants comes from four production wells and three injection wells that are between 2,100 and 6,000 feet deep with bottom-hole temperatures 469 and 514°F, respectively. In 1981, the hot springs were also the test site of a 1.6 MW biphase turbine research unit. This was a “total flow” turbine that would accept both brine and steam to improve energy conversion by utilizing both the thermal and kinetic energy of the geothermal fluid. However, a conventional flash unit was selected to be installed at the site instead, and thus, the biphase unit was decommissioned.
|GeoSystem=“The commercial geothermal reservoir is associated with the Negro Mag and Opal Mound faults. Production from the geothermal system is primarily from highly fractured Tertiary granite and Precambrian metamorphic rocks bounded to the west by the Opal Dome fault, to the north by the Negro Mag fault, and to the east by the Mineral Mountains.”
The 1.6 MW biphase turbine-generator set was only run for less than a year starting in 1981. As a result of this test, a flash-steam plant was favored over the biphase unit for the permanent installation. The main reason for not selecting the biphase unit, even though it could produce 25% more power as compared to the flash steam type, was reportedly due to the complicated mechanical operation of the plant and the related high maintenance that it required.
Some silica scaling from the approximately 230 ppm was originally experienced from the brine, thus acid injection was started to control the scaling.
|RegEnvIssues=Environmental Noise Considerations Due to a large number of complaints that had arisen since the Geysers Geothermal Field in California had been developed, Roosevelt Hot Springs made a conscious effort to reduce potential environmental noise problems as much as possible prior to development. Developers considered all types of geothermal noise sources, existing ambient noise conditions, locations of noise receptors, and any applicable regulations that were in place prior to development. Based on the analysis performed, it was decided that environmental noise is not a concern at Roosevelt Hot Springs - or any other known geothermal resource areas in Southwest Utah.
|DOEInvolve=In 2000, DOE funded an R&D grant at Roosevelt for the testing and feasibility analysis of a high-efficiency binary heat recovery cycle known as the Kalina Cycle. The Kalina Cycle was designed to recover energy at temperatures as low as 171°C from silica-rich geothermal brine from an existing geothermal plant on the facility that was previously being re-injected. The scope of work also included determination if pH modification (acid injection) would be able to prevent or delay destructive silica precipitation within the power cycle components. The study was able to confirm that the Kalina Cycle is suitable for such an application
Blundell Unit 3 is a proposed 33 MW (net) double-flash plant. The double-flash technology was selected due to its lower capital cost per installed megawatt and higher efficiency (about 20% more power output over single-flash units). The unit will require drilling four production wells to 5,000 feet and four injection wells to 6,500 feet. The goal is to produce a geothermal resource between 500 and 650°F. Five steam separators (four high-pressure and one low-pressure) will also be required. Sixteen miles of transmission line upgrades will also be required. The plant is still in the design phase with no fixed time set to start construction.