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Mammoth G2 — Power plant · Geothermal · Ormat Nevada Inc
  • Clean firm
  • Operating
  • 10 · 100 · 1,000 MW

Mammoth G2

Power plant · Geothermal

Key facts

Power plant · Geothermalran 64% of 2025 Operating
Capacity
Capacity: sourceEIA-860M · Open licenseMW
Commissioned
1990
Net generation, 2025
83,764 MWh
Grid
33 kV to Southern California Edison Co (CISO)
Location
Mono County, California
Operated by
Ormat Nevada Inc

Output

Net generation MWh by year, 2001 to 2025

Operations detail

Details

Who’s behind it

Owner
Mammoth Pacific LP

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Technology
Geothermal source: “Geothermal”
Age
36 years since 1990
All 5 attributes from EIA-860M Preliminary Monthly Electric Generator Inventory
AttributeValue
Gem
Unit ids
G100000700509, G100000700510, G100000700511
Location id
L100000700278
Eia plant ids
10481
Fuel burned (MMBtu), 2025285,803
Capacity factor, 20250.637
Net generation (MWh), 202583,764
Balancing authority codeCISO

Retirement

EIA-860M September 2026StatusSome generators have retired; the rest of the plant is still in service. As of EIA-860M for September 2026.
Capacity retired
15 MW
Generators retired
3
Capacity still in service
15 MW
GeneratorTechnologyNameplateStateDate
T101Geothermal5 MWRetiredApril 2013
T102Geothermal5 MWRetiredApril 2013
T103Geothermal5 MWRetiredApril 2013

Grid

EIA-860 2025Grid fieldsAs the plant reported them to EIA-860 for 2025 (Schedule 2).
Grid voltage at the plant
33 kV
Transmission or distribution system owner
Southern California Edison Co
Balancing authority
California Independent System Operator
NERC region
WECC
Transmission lines within 15 mi (1)
Can the connection be reused?

A plant that retires usually leaves its substation, transmission connection and interconnection agreement behind, and those may be reusable by a new project at the same site. FERC Order No. 845 lets an interconnection customer use surplus interconnection service at an existing site, and some transmission providers' tariffs let a replacement resource take over a retiring unit's interconnection service, usually within a set time after the retirement. Whether any such right still exists here, who holds it and on what terms depends on the owner, the transmission provider and timing; this page does not establish any of that.

Ownership

2 companies2
CompanyRoleShareAs ofSource
Ormat Nevada Inc Operator EIA-860M
Mammoth Pacific LP Owner 100.0% Dec 31, 2025 EIA-860

Timeline

  • Stated Units T101, T102, T103 scheduled to retire, 15 MW · EIA-860M
  • In service · EIA-860M

Sources

6 sources

Sources EIA-860M · GEM · LBNL · EIA · EIA-860M Preliminary Monthly Electric Generator Inventory · EIA-860 Annual Electric Generator Report — Schedule 4 Owner (ownership shares per generator), plus Plant/Generator schedules

Sources

  • EIA-860MOpen license · retrieved Nov 4, 2026
  • GEMOpen license, with credit · retrieved Oct 26, 2026Global Integrated Power Tracker, Global Energy Monitor, September 2026 release (https://globalenergymonitor.org/projects/global-integrated-power-tracker), CC BY 4.0. Modified by Inframation: TransitionZero-sourced rows removed; statuses and technologies mapped to Inframation's vocabulary; figures aggregated. Copyright © Global Energy Monitor. Global Integrated Power Tracker, September 2026 release. Distributed under a Creative Commons Attribution 4.0 International License.
  • LBNLOpen license, with credit · retrieved Nov 9, 2026Yin, Nait Belaid & Heleno (2026), Lawrence Berkeley National Laboratory, OEDI, CC BY 4.0: A Harmonized Geospatial Dataset of U.S. Transmission Lines: Linking FERC Form 1 and HIFLD, 1994-2024. Modified by Inframation: HIFLD-side fields only, names re-cased, coordinates rounded.
  • EIAOpen license · retrieved Nov 1, 2026Source: U.S. Energy Information Administration, Electricity bulk data (Form EIA-923 monthly plant series)
  • EIA-860M Preliminary Monthly Electric Generator Inventory
  • EIA-860 Annual Electric Generator Report — Schedule 4 Owner (ownership shares per generator), plus Plant/Generator schedules

Every source and license · Attribution

View at source