Frontier Observatory for Research in Geothermal Energy (FORGE) is a US government program supporting research into geothermal energy. [1] The FORGE site is near Milford, Utah, funded for up to $140 million. As of 2023, numerous test wells had been drilled, and flux measurements had been conducted, but energy production had not commenced. [2]
In February 2014, the Department of Energy (DOE) announced the intent to establish "a dedicated subsurface laboratory" [1] to investigate and develop enhanced geothermal systems. [3] In June 2018 DOE funded a location outside of Milford, Utah for up to $140 million. [4]
The site is located along the Colorado Plateau and Basin and Range Province transition zone. It is primarily composed of intrusive Oligocene through Miocene batholith emplaced into Precambrian metamorphic (Gneiss) and Paleozoic sedimentary rocks. [5] [6] The site is west of the Mineral Mountains and about two km east of the north–south trending Opal Mond Fault (OMF), perpendicular to the east–west trending Negro Mag Fault (NMF). [5] [7] FORGE is dominated by a fault-fracture mesh system with OMF as one of its most active features. [6] [8] Fault structures vary from steeply dipping faults west of the Mineral Mountains to more gently steeping faults to the east. [6] [5]
The reservoir is located approximately between 1,525 and 2,896 meters (~5,000-10,000 ft) depth in which temperature ranges from 175 to 225 °C. [9] The rock is aged from 8 Ma to 25.4 Ma. [10] [11] [12] Roosevelt Hot Springs (RHS) to the east is a hydrothermal area with temperatures ranging from about 100°C at the surface to over 250 °C at a depth of roughly 4000 meters (13,123.4 ft). [8] These temperatures indicate the presence of cooling magma in the shallow crust. [8]
More than 80 shallow gradient wells (<500 m depth) and 20 deeps wells (>500 m depth) were drilled. [13] [14] Analyses from the shallow well data reported that the encountered granitic rocks were not producing fluids, but were hot. [13] A lack of fluid production indicated these rocks are impermeable and that the site is a classic example of a hot dry rock energy system. [9] The thermal grounds cover most of the northern Milford valley. [13] [14] The highest temperature wells (greater than 80 °C) are located east of the OMF above the RHS hydrothermal system. [14] Near-surface profiles (less than 80 m depth) of temperature gradient are similar in central, southern and western sectors at roughly 70 °C per km and do not exceed 270 °C, even at higher temperature wells to the west. [14]
The primary well descends vertically 6,000 feet (1.8 km), then continues 5,000 feet (1.5 kilometers) at a 65 degree angle. The well employed a diamond-tipped bit, cutting drilling costs by 20 percent. [2]
A geyser is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in a few places on Earth. Generally all geyser field sites are located near active volcanic areas, and the geyser effect is due to the proximity of magma. Generally, surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it contacts hot rocks. The resultant boiling of the pressurized water results in the geyser effect of hot water and steam spraying out of the geyser's surface vent.
Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.
A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma or by circulation through faults to hot rock deep in the Earth's crust. In either case, the ultimate source of the heat is the radioactive decay of naturally occurring radioactive elements in the Earth's mantle, the layer beneath the crust.
Geothermal energy is thermal energy in the Earth's crust. It combines energy from the formation of the planet and from radioactive decay. Geothermal energy has been exploited as a source of heat and/or electric power for millennia.
Hydrothermal circulation in its most general sense is the circulation of hot water. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's crust. In general, this occurs near volcanic activity, but can occur in the shallow to mid crust along deeply penetrating fault irregularities or in the deep crust related to the intrusion of granite, or as the result of orogeny or metamorphism. Hydrothermal circulation often results in hydrothermal mineral deposits.
Valles Caldera is a 13.7-mile (22.0 km) wide volcanic caldera in the Jemez Mountains of northern New Mexico. Hot springs, streams, fumaroles, natural gas seeps and volcanic domes dot the caldera floor landscape. The highest point in the caldera is Redondo Peak, an 11,253-foot (3,430 m) resurgent lava dome located entirely within the caldera. Also within the caldera are several grass valleys, or valles, the largest of which is Valle Grande, the only one accessible by a paved road. In 1975, Valles Caldera was designated as a National Natural Landmark by the National Park Service with much of the caldera being within the Valles Caldera National Preserve, a unit of the National Park System.
Geothermal gradient is the rate of change in temperature with respect to increasing depth in Earth's interior. As a general rule, the crust temperature rises with depth due to the heat flow from the much hotter mantle; away from tectonic plate boundaries, temperature rises in about 25–30 °C/km (72–87 °F/mi) of depth near the surface in most of the world. However, in some cases the temperature may drop with increasing depth, especially near the surface, a phenomenon known as inverse or negative geothermal gradient. The effects of weather, the Sun, and season only reach a depth of roughly 10–20 m (33–66 ft).
Sedimentary exhalative deposits are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulphide minerals. SEDEX deposits are hosted largely by clastic rocks deposited in intracontinental rifts or failed rift basins and passive continental margins. Since these ore deposits frequently form massive sulfide lenses, they are also named sediment-hosted massive sulfide (SHMS) deposits, as opposed to volcanic-hosted massive sulfide (VHMS) deposits. The sedimentary appearance of the thin laminations led to early interpretations that the deposits formed exclusively or mainly by exhalative processes onto the seafloor, hence the term SEDEX. However, recent study of numerous deposits indicates that shallow subsurface replacement is also an important process, in several deposits the predominant one, with only local if any exhalations onto the seafloor. For this reason, some authors prefer the term "Clastic-dominated zinc-lead deposits". As used today, therefore, the term SEDEX is not to be taken to mean that hydrothermal fluids actually vented into the overlying water column, although this may have occurred in some cases.
Geothermal energy was first used for electric power production in the United States in 1960. The Geysers in Sonoma and Lake counties, California was developed into the largest geothermal steam electrical plant in the world, at 1,517 megawatts. Other geothermal steam fields operate in the western US and Alaska.
An enhanced geothermal system (EGS) generates geothermal electricity without natural convective hydrothermal resources. Traditionally, geothermal power systems operated only where naturally occurring heat, water, and rock permeability are sufficient to allow energy extraction. However, most geothermal energy within reach of conventional techniques is in dry and impermeable rock. EGS technologies expand the availability of geothermal resources through stimulation methods, such as 'hydraulic stimulation'.
Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 26 countries, while geothermal heating is in use in 70 countries.
Hot Creek, starting as Mammoth Creek, is a stream in Mono County of eastern California, in the Western United States. It is within the Inyo National Forest.
The Iceland Deep Drilling Project (IDDP) is a geothermal project established in 2000 by a consortium of the National Energy Authority of Iceland (Orkustofnun/OS) and four of Iceland's leading energy companies: Hitaveita Sudurnesja (HS), Landsvirkjun, Orkuveita Reykjavíkur and Mannvit Engineering. The consortium is referred to as "Deep Vision".
AltaRock Energy Inc. is a privately held corporation that focuses on the development of geothermal energy resources and enhanced geothermal systems (EGS). It is headquartered in Seattle, Washington and has a technology development office in Sausalito, California. AltaRock has filed patent applications and holds exclusive licenses for related intellectual property related to EGS. In 2008 it started its first project near The Geysers in California to demonstrate the ability of EGS to be a reliable, renewable and clean source for the production of electric power.
Geothermal exploration is the exploration of the subsurface in search of viable active geothermal regions with the goal of building a geothermal power plant, where hot fluids drive turbines to create electricity. Exploration methods include a broad range of disciplines including geology, geophysics, geochemistry and engineering.
The Yangbajain Geothermal Field (羊八井地热田) is a geothermal field near the town of Yangbajain in Damxung County, Tibet Autonomous Region, China. The fluid is heated by magmatic activity not far below the surface. It is a tourist attraction and also supplies steam to a major power plant with 25 MW capacity.
Apacheta-Aguilucho volcanic complex is a volcanic complex in Chile. It consists of two volcanoes Cerro Apacheta and Cerro Aguilucho, which are constructed mainly by lava flows and surrounded by outcrops of lava. A sector collapse and its landslide deposit are located on Apacheta's eastern flank. Two lava domes are associated with the volcanic complex, Chac-Inca and Pabellón.
Mystic Hot Springs, previously known as Monroe Hot Springs and Cooper Hot Springs are located in northeastern Monroe, Utah. The hot mineral water emerges from the spring at 168 °F (76 °C). The water flows into two smaller pools with temperatures between 92 and 102 °F.
Fault zone hydrogeology is the study of how brittlely deformed rocks alter fluid flows in different lithological settings, such as clastic, igneous and carbonate rocks. Fluid movements, that can be quantified as permeability, can be facilitated or impeded due to the existence of a fault zone. This is because different mechanisms that deform rocks can alter porosity and permeability within a fault zone. Fluids involved in a fault system generally are groundwater and hydrocarbons.
Geothermal activity is a group of natural heat transfer processes, occurring on Earth's surface, caused by the presence of excess heat in the subsurface of the affected area. Geothermal activity can manifest itself in a variety of different phenomena, including, among others, elevated surface temperatures, various forms of hydrothermal activity, and the presence of fumaroles that emit hot volcanic gases.
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