What is Geological Storage?

Geological Energy Storage uses space in the subsurface such as, salt dome caverns, pore space in saline aquifers, or pore space in hydrocarbon reservoirs to store energy in different form. This could be the mechanical energy in a compressed fluid such air, or the chemical energy in a fluid like hydrogen, or something else yet to be uncovered.

There are over 2 Million idle oil & gas wells in the United States. Rather than abandoning these wells, operators can repurpose their stranded assets into energy storage facilities using idle wells to access the enormous pore volumes underground for energy storage. The potential forTerawatt-hours of energy storage throughout the United States exists by making available innovative technologies for repurposing oil & gas infrastructure, and coupling electricity consumers, with renewable generators, operators and land owners.

Many energy storage technologies are ultimately limited by the capital cost of their storage capacity e.g. the cost of a battery grows with the mass or volume of the battery as its energy storage capacity grows. Geological Storage offers immense volumes where the cost of accessing the volume grows very slowly - it allows for a near zero marginal cost of storage. At grid-scale: power capacities of 100+MW, durations longer than 10 hours through 1000s of hours - utilizing the subsurface can cut costs by 10-100x compared with other technology pathways.

Compressed Air Energy Storage (CAES)

THEMES has developed an LDES system coupling proven adiabatic surface plant with innovative technologies to repurpose the subsurface for energy storage in the saline aquifer zone, accessed via idle oil & gas well infrastructure.

THEMES is working with a coalition of partners including University of Southern California, national labs, a large O&G operator, and a well-known EPC on a first commercial 100MW 12-hour project in California.

THEMES has a current projected LCOS of $0.12/kWh with an identified pipeline of projects with a cumulative 1 GW power capacity, 12 hour duration.

Compressed Natural Gas

THEMES is working with NREL to demonstrate using compressed natural gas for seasonal energy storage. The process involves using excess renewables to compress natural gas from the sales pipeline. When power is needed, gas can be brought up and expanded through an expansion turbine before re-entering the sales line.

THEMES is working to develop an initial demonstration and is in search of operators interested in energy storage.