US4137720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Use of calcium halide-water as a heat extraction medium for energy recovery from hot rock systems
Assignee: Republic Geothermal Inc
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Filing: 1977-03-17
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Granted: 1979-02-06
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Expires: 1997-03-17
Abstract
Abstract In order to extract energy in a matter more efficient than is presently known to the art, from hot dry rock geothermal systems, a mixture of water and calcium chloride is used. The fluid mixture is injected into a formation and forced through the formation with simultaneous extraction of heat from the energy recovery or heat extraction surrounding rocks. The fluid and a larger fraction of its contained energy are then recovered than can presently be recovered by technology known to the art.
Inventors
- 👤 Robert W. Rex
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:29
CPC Classifications
F; F24; F24T; F24T10/00; F24T10/20; F03; F03G; F03G4/00; F03G4/074; Y; Y02; Y02E; Y02E10/00; Y02E10/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
An improved heat extraction fluid for use in hot, dry rock geothermal systems comprising a brine mixture of water and a calcium halide, said mixture having a specific gravity of approximately 1.4 to 1.5 when at a temperature of approximately 20° C., whereby when said brine is injected to and heated by the hot, dry rock formation its specific gravity will be reduced to approximately 1.0 resulting in a more energy efficient pressure gradient in the geothermal system.
Claim 2
Dependent Claim
78 words
An improved heat extraction fluid for use in hot, dry rock geothermal systems comprising a brine mixture of water and a calcium halide, said mixture having a specific gravity of approximately 1.4 to 1.5 when at a temperature of approximately 20° C., whereby when said brine is injected to and heated by the hot, dry rock formation its specific gravity will be reduced to approximately 1.0 resulting in a more energy efficient pressure gradient in the geothermal system.
Claim 3
Dependent Claim
31 words
The heat extraction fluid of claim 1 wherein said calcium halide is selected from the group consisting of calcium chloride calcium bromide and a mixture of calcium chloride and calcium bromide.
Claim 4
Dependent Claim
31 words
The heat extraction fluid of claim 2 wherein said fluid contains approximately 1 to 50% of a calcium halide by weight, 10 to 20% acetone by weight and the remainder water.
Claim 5
Dependent Claim
16 words
The heat extraction fluid of claim 2 which further includes a ketone mixed with said fluid.
Claim 6
Dependent Claim
12 words
The heat extraction fluid of claim 4 wherein said ketone is acetone.
Claim 7
Dependent Claim
17 words
The use of the heat extraction fluid of claim 4 in a pulse mode of heat extraction.
Claim 8
Independent Claim
44 words
A method of operating geothermal well which includes the steps of introducing a fluid medium into a hot rock system, said fluid medium including a mixture of water and calcium chloride, and recovering useful energy from the resulting heated fluid medium from said well.
Claim 9
Independent Claim
44 words
A method of operating geothermal well which includes the steps of introducing a fluid medium into a hot rock system, said fluid medium including a mixture of water and calcium chloride, and recovering useful energy from the resulting heated fluid medium from said well.
Claim 10
Dependent Claim
30 words
The method according to claim 7 wherein said heat extraction fluid contains approximately 1 to 50% calcium chloride by weight, 10 to 20% acetone by weight and the remainder water.
Claim 11
Dependent Claim
36 words
The method of claim 7 wherein said fluid medium is introduced in a pulse mode of heat extraction and further including adding a high vapor pressure additive to said fluid medium to reduce operational energy consumption.
Claim 12
Dependent Claim
24 words
The method of claim 9 wherein said additive is selected from the group consisting of methane, ethane isopropanol, acetone, dioxane, methyl ketone and ammonia.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-05 | 1982-08-07 | 1983-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-05 | 1986-08-07 | 1987-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-05 | 1990-08-07 | 1991-02-06 | $7700.00 | Window Closed / Lapsed |