Subsurface Steam Heat Storage in Depleted Oil Reservoirs
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Solution Overview
Problem
Current energy storage systems for heat generated by concentrating solar power are inefficient and lack utility in providing continuous and seasonal energy solutions, with significant heat loss and parasitic loads in above-ground systems.
Innovation Solution
A subsurface thermal energy storage system utilizing saturated steam as a heat transfer fluid, injected into depleted oil fields, which minimizes heat loss and allows for long-term storage and efficient energy delivery, using existing infrastructure and geothermal technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If above-ground thermal energy storage systems are used, then energy storage capacity is achieved, but heat loss and parasitic loads increase significantly
Solution Approach 1:
The patent introduces saturated steam as an intermediary heat transfer fluid to transfer thermal energy from concentrating solar power systems to subsurface storage reservoirs. This steam intermediary enables efficient heat transfer while eliminating the need for complex above-ground thermal storage infrastructure, directly resolving the contradiction between minimizing heat loss and reducing infrastructure complexity.
Solution Approach 2:
The patent transitions thermal energy storage from the above-ground dimension to the subsurface dimension by injecting saturated steam into underground reservoirs. This dimensional shift exploits the natural insulating properties of subsurface geology to minimize heat loss while eliminating complex above-ground infrastructure, simultaneously improving energy retention and reducing system complexity.
2Productivity
If above-ground thermal storage systems are implemented, then energy storage is provided, but heat loss reduces efficiency
Solution Approach 1:
Saturated steam serves as an intermediary that efficiently transfers thermal energy from solar concentrators to subsurface reservoirs with minimal heat loss. The steam's high heat capacity and efficient heat transfer properties enable high productivity energy delivery while the subsurface environment minimizes thermal losses, resolving the contradiction between energy delivery efficiency and heat loss reduction.
3Duration of action of stationary object
If conventional energy storage systems are used, then short-term storage is achieved, but seasonal and continuous energy solutions are lacking
Solution Approach 1:
The patent extends energy storage from short-term above-ground systems to long-term subsurface reservoirs by transitioning to the subsurface dimension. The natural thermal insulation of underground geology enables seasonal storage durations while the ability to inject and extract steam on demand maintains continuous energy delivery productivity, resolving the contradiction between extended storage duration and continuous energy supply.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient, continuous, and seasonal thermal energy storage with reduced heat loss, addressing the intermittency of solar power and providing stable energy delivery, while reducing the need for additional infrastructure.
Implementation Method 1
Fluid for transfer of heat energy from the surface to an underground storage volume (such as a depleted oil field) is saturated steam
Implementation Method 2
subsurface thermal energy storage system utilizing saturated steam as a heat transfer fluid, injected into depleted oil fields, which minimizes heat loss and allows for long-term storage
Data Source
AI summary
Techniques for subsurface thermal energy storage of heat generated by concentrating solar power enable smoothing of available energy with respect to daily and/or seasonal variation. Solar thermal collectors produce saturated steam that is injected into a producing or wholly/partially depleted oil reservoir that operates as a heat storage reservoir. Some of the saturated steam generated by the collectors is optionally used to generate electricity. Heat is withdrawn from the reservoir as saturated steam and is used to operate an active thermal recovery project (such as a producing thermally enhanced oil reservoir) and/or to generate electricity. Withdrawn heat is optionally augmented by heat produced by firing natural gas. The reservoir is optionally one that has been used for thermally enhanced oil recovery and thus is already warm, minimizing heat losses.