Mammoth Geothermal Complex

The complex consists of four binary-cycle geothermal power stations, each with a nameplate capacity of 10 MW. Mammoth Pacific 1 (MP1) was commissioned in 1984 and was the first air-cooled geothermal power station in the world. Mammoth Pacific 2 (MPII) and PLES-1 were both commissioned in 1990 and use the same air-cooled technology.

In 2005, the geothermal well field was expanded into Basalt Canyon just west of the three power stations. Two production wells were drilled and connected to the existing power plants. In 2014, Ormat replaced the 30-year-old equipment of MP1 in order to improve its efficiency.

In 2006, Ormat proposed the construction of a 30 MW binary cycle geothermal power plant called Casa Diablo IV that would double the generating capacity of the geothermal complex.{{Cite web|url=http://www.mammothpacific.com/?q=node/15|title=Casa Diablo IV Project {{!}} mammothpacific|website=www.mammothpacific.com|access-date=2020-02-09}}

In 2014, the Mammoth Community Water District (MCWD) sued the Great Basin Unified Air Pollution Control District (GBUAP) and ORNI 50 LLC (Ormat) over concerns that the power plant would compromise the water supply of Mammoth Lakes. GBUAP and Ormat disputed this, arguing there was no connectivity between the deep geothermal reservoir and MCWD's groundwater aquifer based on extensive research conducted on the site. On June 25, 2015, the Mono County Superior Court ruled in favor of GBUAP and Ormat. In addition, on August 31, 2015, the Interior Board of Land Appeals denied an appeal made by MCWD.{{Cite web|url=https://www.kcet.org/redefine/mammoth-residents-concerned-over-geothermal-plant-threat-to-groundwater|title=Mammoth Residents Concerned Over Geothermal Plant Threat to Groundwater|last=Clarke|first=Chris|date=2014-06-16|website=KCET|language=en|access-date=2020-02-09}}{{Cite web|url=http://www.mammothpacific.com/sites/mammoth.dev4.linnovate.net/files/Lawsuit%20Blurb%20v2.pdf|title=Mammoth Community Water District v. Great Basin Unified Air Pollution Control District and ORNI 50 LLC|last=|first=|date=|website=|archive-url=|archive-date=|access-date=8 February 2020}}

Casa Diablo IV is expected to be operational by the end of 2021.{{Cite web|url=https://www.thinkgeoenergy.com/ormat-signs-ppa-with-community-choice-aggregator-for-new-30-mw-geothermal-plant-in-california/|title=Ormat signs PPA with community choice aggregator for new 30 MW geothermal plant in California|website=Think GeoEnergy - Geothermal Energy News|language=en-US|access-date=2020-02-09}} As of July 14th, 2022, Ormat announced that commercial operations at Casa Diablo IV had begun. {{Cite web |title=StackPath |url=https://www.ormat.com/en/company/news/view/?ContentId=9205 |access-date=2023-03-10 |website=www.ormat.com}}

{{main|Long Valley Caldera}}

The Mammoth Geothermal Complex is located at the base of a large resurgent dome near the center of the Long Valley Caldera. The dome was formed from the swelling or rising of the caldera floor due to movement in the magma chamber beneath it. The geothermal heat produced from the magma chamber below the dome causes groundwater to boil and turn to steam, creating fumaroles such as those seen in Fumarole Valley and along Hot Creek about {{convert|5|mi|km}} to the northeast. The geothermal complex utilizes this heat to power its binary-cycle power generators.

• List of geothermal power stations in the United States
• List of power stations in California

{{Commons category|Mammoth Geothermal Complex}}

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{{Generating stations in California|state=autocollapse}}

Category:1984 establishments in California

Category:Buildings and structures in Mono County, California

Category:Energy infrastructure completed in 1984

Category:Geothermal power stations in California