FervoFlex: Long duration in-reservoir energy storage and load-following, dispatchable geothermal generation

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OPEN 2021
Berkeley, California
Project Term:
08/22/2022 - 08/21/2024

Technology Description:

Fervo Energy has developed proprietary geothermal technology—FervoFlex™—capable of delivering in-reservoir energy storage and dispatchable generation attributes. At the same time, the team will develop a fiber optics-based diagnostic platform to monitor and optimize dynamic subsurface processes that currently pose major barriers to flexibly operating geothermal facilities. Fervo’s horizontal well design connects subsurface wells with a set of hydraulically conductive fractures surrounded by impermeable rock. These fractures act as flow pathways, providing contact areas with the geothermal reservoir to enable sustained heat recovery, and the low-permeability rock prevents fluid leak-off. Charging and discharging cycles are performed by controlling the injection and production well flow rates and pressures to deliver flexible generation profiles in response to grid demands and time-shift energy at high round-trip efficiencies. The FervoFlex™ technology effectively enables Fervo to operate their assets to achieve multi-day energy storage attributes in addition to the traditional benefits of clean, firm geothermal power.

Potential Impact:

Firm, zero-carbon, dispatchable resources are key to unlocking a fully decarbonized electricity sector.


Geothermal energy is reliable, flexible, and requires no fuel inputs to maintain operations. It will increase the resilience and reliability of the electric grid.


When coupled with organic Rankine cycle generators, geothermal energy is a clean energy resource with zero emissions or pollutants that requires minimal land use.


Making geothermal flexible would realize a $300+ billion market opportunity.


ARPA-E Program Director:
Dr. Isik Kizilyalli
Project Contact:
Dr. Jack Norbeck
Press and General Inquiries Email:
Project Contact Email:


Lawrence Berkeley National Laboratory

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