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There are already three topics that include "geothermal" in the title....
As nearly as I can tell, all these topics assume that thermal energy would be drawn from the crust of the Earth.
This topic is different, because the concept is to use the thermal energy of the crust as an insulation layer around a store of thermal energy created by renewable energy devices on the surface.
As noted in a paper about CAES (Compressed Air Energy Storage) found and posted by Void in 2024, a major drawback of CAES systems is the loss of thermal energy accumulated in compressed gas, as these systems are currently implemented.
This topic is offered for NewMars members who might wish to study or perhaps even design an energy storage system that takes advantage of the thermal energy already stored in the Earth's crust, without drawing any of that energy.
Calliban has warned NewMars readers on numerous occasions that the material found in the Earth's crust is a poor conductor of thermal energy, and that if humans draw some of that energy from a volume of crust, it will take a long time for the Earth to replace the energy drawn.
This topic is offered as an alternative to drawing energy slowly accumulated by the Earth over eons. Instead, that energy can serve as an insulation layer for a human high temperature store. Some of the high levels of thermal energy stored by humans may pass into the surrounding crust, but the Earth itself will gently push back against this intrusion, and tend to restore that energy to the repository when it is drawn down.
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This post is reserved for an index to posts that may be contributed by NewMars members over time.
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We now appear to have two competing visions for how this topic will develop.
In the competition I hope to see in the weeks ahead, readers and members alike ** should ** be able to study carefully reasoned presentations on the advantages and disadvantages of the competing designs
On the simplistic side, we have the suggestion of simple compression of air in an abandoned oil well. The potential drawbacks of this design have been partially identified by kdb512 in several other topics. The advantage of this design is simplicity, and immediate return on the investment.
On the other side, where a bit more complexity is offered in a bid to improve the capabilities and the reliability of the system, we have a proposal by kbd512 to drop a loop of pipe down the abandoned well, and surround that loop with a suitable material. Suggested materials might include a suitable salt.
Since the site of the system is proposed to be an abandoned oil well made of iron pipe, the material chosen will have excellent thermal properties while at the same time not removing iron atoms from the wall of the pipe.
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The link below is to a paper published in 2024.
The focus of the paper is storage of thermal energy, and it covers a number of salt candidates.
An interesting characteristic of the enclosure is the use of graphite for the walls.
Presumably this is done in a bid to reduce corrosion.
https://www.sciencedirect.com/science/a … preferable.
Note: Table 2 contains a list of recommendedsalt PCM candidates
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In a bid to try to put the forum on a path toward real achievement in the Real Universe, here is a web site that lists abandoned oil wells in Texas. I'm sure there are similar web sites in other states and perhaps in other Nation.
https://www.rrc.texas.gov/oil-and-gas/r … 12-months/
Orphan Wells with Delinquent P-5 Greater Than 12 Months
Orphaned wells are inactive, non-compliant wells that have been inactive a minimum of 12 months and the responsible operator's Organizational Report (Form P-5) has been delinquent for greater than 12 months. Operators desiring to take over these wells must have an active Organization Report (Form P-5) and, upon request, provide a good faith claim to operate the wells.Procedure for Taking Over An Orphaned Well
Reimbursement to Surface Owners of Certain Costs Incurred for Plugging an Orphan Oil or Gas Well
An Orphan Well Query is available to search orphan wells by Well Type, District, County, Field, Operator and API Number.Access the Orphan Well Query and other Oil and Gas data.
An Excel version of the entire list of orphan wells for the current month is available for a download as a zip file.This page was last updated on: Friday, September 13, 2024
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The two competing concepts at work in this topic are:
1) Simple compression of gas in the existing iron well pipe, including installation of a blowout cap at the bottom, and suitable equipment at the top to perform compression and recovery operations.
2) A salt storage system carefully designed to avoid destroying the iron pipe.
The salt storage concept has a lot going for it, but capital investment will be substantial.
The investor must find a salt that will not destroy the iron wall of the well, and purchase enough tons of this material to fill the space between the inside wall of the well and the walls of the loop of pipe that is to carry a fluid to heat the salt, and then recover energy from the salt.
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The text below is from the Texas web site where orphan oil well are listed....
The text makes clear that the agency involved is looking for operators who will cover all the costs related to the previous operation, and be able to assure the agency that the intention is to operate the well, ** and ** to cap it properly when the well is no longer useful.
Procedure for Taking Over an Orphan Well
Definition of Orphan Well
Orphaned wells are inactive, non-compliant wells that have been inactive a minimum of 12 months and the responsible operator's Organizational Report (Form P-5) has been delinquent for greater than 12 months. Operators desiring to take over these wells must have an active Organization Report and, upon request, provide a good faith claim to operate the wells.Requirements For Taking Over an Orphan Well
The acquiring operator must have an Active P-5.
The acquiring operator cannot have outstanding final orders ("639").
The acquiring operator must be a "bonded operator" (Opt 1 or 2 financial assurance in the form of a performance bond, letter of credit, or cash deposit).
The acquiring operator must have sufficient financial assurance to cover the acquisition, along with all currently operated wells.
Any Form P-4, Producer's Transportation Authority and Certificate of Compliance holds placed on the well(s) by the Commission for non-compliance must be addressed with the appropriate Commission section (Field Operations, Enforcement or Well Plugging) prior to the transfer.
The acquiring operator must have (and may be required to provide proof of) a good-faith claim to operate the well(s).
The appropriate forms to transfer the well(s) to the acquiring operator must be filed with and approved by the Commission.
Two signature Form P-4s - When the current delinquent operator’s signature can be obtained, a Form P-4 with signatures of the current operator and the acquiring operator may be filed.
Single signature Form P-4s - When a signature cannot be obtained from the current delinquent operator, a Form P-4 may be filed with only the acquiring operator’s signature, but the acquiring operator must also provide a letter explaining why the prior operator has not signed (e.g., he cannot be found after a diligent search or he refuses to sign) and documentation establishing that the acquiring operator has at least a good-faith claim to the right to operate the wells(s).
Oil lease subdivision - If the acquiring operator is only taking over certain oil wells on an existing lease and not the entire oil lease, in addition Form P-4 filing requirements, the acquiring operator must file a Form P-6, Request for Permission to Consolidate/Subdivide Leases, before and after plats outlining the configuration of the lease, and a statement that no overproduction exists on the lease.
Good faith claim to operate - For all single signature Form P-4s and for other Form P-4 transfers when requested by the Commission, proof of good faith claim to operate the wells must be filed with the Commission.
Plugging & Compliance ResponsibilityAny operator who successfully acquires an orphaned well, acknowledges responsibility for the regulatory compliance of the wells they are acquiring and for the proper plugging of the well(s) pursuant to 16 Texas Administrative Code §3.14 (Statewide Rule 14) through their signature on the Form P-4. Additionally, the acquiring operator assumes responsibility for the physical operation and control of the wells, and acknowledges that they will remain designated as the responsible operator of record until a new operator designation is approved by the Commission.
Contact Information
For questions related to:
Form P-5 or Financial Assurance contact the P-5 Section at 512-463-6772
Form P-4 or Form P-6 Subdivisions contact the Proration Section at 512-463-6975
Good Faith Claim to Operate Requirement contact the Office of General Counsel at 512-463-6848
SB639 Holds or Enforcement Holds contact the Enforcement Section at 512-463-6762
Field Operations, State Plugging Holds or Orphan Well List contact the Field Operations Section at 512-463-6830
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And here is a message from FriendOfQuark1 who lives in Texas...
I had asked about the ability of oil wells to withstand pressure, and the modern ones appear to have some ability along those lines.
It depends on the type of well and the type of formation. I don't think you'd get enough pressure to burst the liners, it would be the pay zone that would fracture first. Imagine if wells were fracked with highly compressed air instead of water for example. The oldest wells of the simple straw straight type have all be cemented closed and can't be use. A few new wells of this type still get drilled. Many of them are "in the chalk" however and the formation gets treated with thousands of gallons of strong acid. This formation might tend to be friable after the oil and gas have been removed.
The newest hydraulic fractured wells, can certainly take a quarter million PSI of pressure without bursting the liners (they use pressures that high to frack the shale as normal operating procedure now). But these depleted wells tend to be held in reserve. (most of them are actually still technically producing as "stripper wells"). That is, they produce less than 50 barrels a day and sometimes can be operated at a trickle of as little as 2 barrels a day just trickling from the formation (submersible pump technology made a huge leap forward shortly after the turn of the millenium.) They can generally be fracked a second and even third time if market conditions are right. They are basically being held in case of a major global oil shock where the US can no longer import foreign oil but still wants to export finished and semi finished chemical products and fuels.
That is, I don't think anyone who has the rights to such wells will let you have them at a price point that makes your idea economically viable. You might be able to if you had big money place stalking horse bids on the wells when they have been fracked enough times they are no longer worth the trouble and implement this a decade from now? They would be 'cheap' at this point as they are an environmental liability and need to be cemented. All of this brings up thorny legal issues. Say you are in the West Texas Permian basin, who owns the "air compression rights"? I assume the railroad commission would consider this part of the mineral rights. How much do you have to pay in royalties, and to who? How is the deal structured? How do you insure against liability?
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This post is inspired by another reminder from Calliban that geothermal energy in some locations in the crust of the Earth is not automatically renewed, due to poor thermal conductivity of material in the crust where water is not present.
The flip side of the observation is the potential value of a geothermal location as a storage location for thermal energy produced by renewable resources on the surface. If energy is added to the underground store, then it can be drawn upon during winter, without depleting the naturally supplied thermal energy.
Related observation:
Regardless of the poor thermal conductivity of material in the crust, not mediated by water, there is clearly ** some ** thermal conductivity, which provides the temperatures found there. An option is to simply draw from the location at the rate it can be naturally replenished.
The supply of thermal energy from the core of the Earth is inexhaustible. The observation of Calliban appears to be that it takes a long time for thermal energy from the core to percolate through the crust, and the poor thermal conductivity may explain volcanoes, which are natural responses to unwanted restraints.
If humans were to desire to prevent volcanoes, it would seem (to me at least) prudent to draw off excess thermal energy from the core where a volcano would otherwise occur.
A prime location for such an energy harvesting system is beneath the massive volcano threat in the Western US.
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This post is about work done to harvest thermal energy from under the surface of the Earth.
We don't seem to have a topic about this idea, although we do have four topics that include the word "geothermal" in the title.
Void brought the company Fervo to our attention, on one of his topics. This post offers a report on the company.
https://propane.com/environment/podcast … eothermal/
Update: I just re-read the article after scanning it the first time. The company is planning to use fracking technology to solve the problem that Calliban brought to our attention long ago ... perhaps (by now) years ago ... the geothermal resource will expire because the Earth is such a poor thermal conductor.
When a particular field "dries up" the plan is just frack a different field.
Geothermal Isn’t Niche Anymore: Fervo Energy’s Sarah Jewett on Next-Generation Geothermal
6.25 - Geothermal Isn’t Niche Anymore: Fervo Energy’s Sarah Jewett on Next-Generation Geothermal
Sarah JewettGeothermal is having a breakthrough moment and one of the biggest signals is happening right now in southwest Utah. Fervo Energy has begun developing Cape Station, a first-of-its-kind 500-megawatt next-generation geothermal project that could become one of the largest in the world when fully built. Cape Station has drawn national attention, including a recent visit from Bill Gates.
In this episode of Path to Zero, Tucker Perkins talks with Sarah Jewett, Vice President of Strategy at Fervo Energy, about what this Utah project means for the future of clean, firm power and how advances borrowed from the shale revolution are unlocking geothermal in places once considered impossible.
Before joining Fervo, Jewett spent years in the oil and gas sector, including time at Schlumberger, where she worked directly with the subsurface technologies — directional drilling, completions, and reservoir analysis — that now form the backbone of Fervo’s geothermal approach. Trained as a mechanical engineer with additional business and strategy expertise, she brings a rare combination of deep technical fluency and commercial insight to one of clean energy’s most promising frontiers.
Fervo Energy photo
Fervo Energy photo
Reinventing geothermal with oil and gas technology
Fervo’s mission is to reinvent geothermal energy so it becomes the cleanest, most scalable, reliable, and affordable source of power on the grid. Traditional geothermal has been geographically constrained to rare spots with naturally occurring hot water and steam in complex fracture networks underground. Developers had to “get lucky” and hit those fractures with vertical wells, which made the resource risky and hard to scale.
Fervo flips that model. Instead of hunting for perfect natural geology, they create predictable “subsurface radiators” almost anywhere there is hot rock. Using proven tools from the shale industry, such as horizontal drilling, multi-stage completions, fiber-optic monitoring, they drill long horizontal wells into hot rock and engineer the pathways that move heat to the surface. On the surface, the power plant is relatively conventional; the innovation is underground.
As Jewett puts it, there’s hot rock everywhere. The challenge is figuring out how to cost-effectively pull the heat out.
From Project RED to Cape Station
Fervo’s first big milestone was Project RED in Nevada, a combined technology and commercial pilot. Instead of just proving out the engineering, Fervo chose to prove that customers would pay for “firm clean energy” at the same time. They located next to an existing geothermal plant, developed their own horizontal well pair just outside the traditional resource area, and sold hot brine into the existing facility.
Project RED used a three-well system—two 3,500-foot horizontal wells (one injection, one production) and a vertical monitoring well—and now delivers about three megawatts of net power that didn’t exist before. Just as importantly, it showed that Fervo’s approach could work technically and sell commercially.
Cape Station team
Fervo Energy photo
Those lessons are now being applied at a much bigger scale at Cape Station in Beaver County, Utah. Cape Station is planned as a 500-megawatt, two-phase project: 100 megawatts to the grid in 2026, and another 400 megawatts in 2028. Fervo has already completed the well field for phase one—24 wells drilled from three pads—and has significantly reduced drilling costs compared to Project RED by repeating and refining the process.
Jobs, trust, and community benefits
Jewett spends a lot of her time selling the project to the communities where Fervo works. In Milford and Beaver County, Fervo arrived just as a major non-ag employer was laying people off. The biggest question locals had was simple: “When are you going to start hiring?”
Fervo’s answer has been multi-layered. They have roughly 20 full-time Fervo employees based in the local community and around 350 people on-site through contractors and construction firms. The company actively encourages local hiring and works with regional firms such as Rollins Construction and Vortex Crane to keep as much spending in the community as possible.
At the same time, Fervo is careful to acknowledge and address local concerns: induced seismicity, water use, groundwater protection, truck traffic through town, and the visual and noise footprint of the plant. The company works to mitigate risks proactively and to be transparent about what can go wrong, how they aim to prevent it, and how they would respond if something does happen. Over time, Jewett says, building venues for honest dialogue has created trust.
Fervo Energy photo
Fervo Energy photo
Quiet, closed-loop, and low-impact
Compared with many forms of energy development, operating geothermal plants can be surprisingly unobtrusive. Fervo’s designs are closed-loop: geothermal brine is pumped through a heat exchanger, where its heat is transferred to a working fluid that powers the turbines, and then the brine is reinjected underground. There are no big steam plumes venting to the atmosphere, and sound levels are relatively modest.
Water consumption is a concern in the arid West, but Fervo uses air-cooling on its plants and keeps brine in a closed loop rather than venting it, which helps minimize water use and contamination risk. Because there are no hydrocarbons in these reservoirs, many of the chemical and methane issues associated with oil and gas fracking simply don’t apply.
Another key selling point is land efficiency. Jewett notes that Fervo can place around 10 horizontal wells on a single six-acre pad and potentially produce about 50 megawatts of power from that footprint. Replicating that output with solar or solar-plus-storage would typically require far more surface disturbance.
Cost, scaling, and the shale analogy
Historically, geothermal has had a reputation as an expensive, high-risk resource, in part because of “dry wells” and declining reservoir performance. In older projects, developers depended on natural fracture systems that weren’t fully characterized; roughly a third of wells in some fields turned out to be duds, and once the resource declined, there was often no way to economically “recharge” it.
Fervo’s horizontal-well approach is designed to remove both problems. By engineering the fracture network they need, they greatly reduce dry-hole risk. And if temperatures or output decline over time, they can drill new well pairs into the same field to boost production rather than being stuck with a stranded power plant.
Jewett draws a direct analogy to the shale revolution. Techniques like long horizontals, precision fracking, and sophisticated monitoring completely transformed U.S. oil and gas. Many experts said those tools wouldn’t work in geothermal—until Fervo went out and used modern flex rigs, drilled long horizontals into the granitic basement, and proved otherwise. She believes that the same physics-driven toolkit can unlock geothermal at a much larger scale.
Policy support, investors, and the cost of capital
On the policy side, geothermal has traditionally been an afterthought, struggling to access the same level of tax incentives that wind and solar enjoy. That changed with recent legislation, including the Inflation Reduction Act, which put geothermal on a more level playing field with solar for at least the next decade. Fervo’s founders deliberately built their business assuming they wouldn’t have generous tax credits forever and are focused on driving down costs quickly enough that the technology can stand on its own.
Even with improved policy, Jewett says the biggest bottleneck now is low-cost capital. Given how capital-intensive geothermal projects are, the ability to attract investors who see the risk as manageable is critical to scaling. Fervo has built credibility in the investor community by setting ambitious but clear technical milestones for each funding round—then achieving them and showing exactly how the money was used. That track record, along with high-profile interest from clean-tech investors and figures like Bill Gates, is helping open the door to more funding.
Fervo Energy photo
Fervo Energy photo
A 20 percent vision for geothermal
Today, geothermal provides about half of one percent of U.S. electricity. Fervo’s internal vision is far more ambitious: Jewett says the company believes geothermal can supply more than 20 percent of the U.S. power grid by 2050—roughly the scale of the current nuclear fleet.
Investors, policymakers, and communities are starting to see that potential. A resource once thought of as niche and location-limited is now being reimagined as scalable, dispatchable, around-the-clock clean power that borrows the best of America’s oil and gas know-how.
It seems to me that this same technology would work at Mars. On Mars the pipes would need to be at least as deep as the ones described in this article.
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tahanson43206,
Silicon Nitride coatings do not add much weight or restrict the interior pipe diameter the way cast basalt liners do. It's applied by chemical vapor deposition and is thus chemically bonded to the base metal. This specific type of coating is exceptionally resistant to salts, even at elevated temperatures.
Externally applied ceramic thermal barrier coatings are a possibility for lower cost and lighter weight heat retention. These coatings can be applied by plasma spray or sprayed on like paint and then baked-on in an oven. If we're talking about Mars, it's near-vacuum atmosphere doesn't allow for much convective or conductive heat loss to occur. If you have a lot of pipe to insulate, weight / money matters, and your system can eat some heat loss, then ceramic coatings are likely to be a more cost-effective option. A ceramic thermal barrier coating won't absorb water, thus won't accelerate corrosion damage over time. It's also easier to inspect a "bare pipe" for signs of damage.
If you do have plenty of locally sourced basalt fiber to work with, then fiber still provides better insulation than a much thinner ceramic aerospace coating. If the pipe is glowing hot, you definitely want the overwrap. Mars has very little atmospheric water vapor for an insulation overwrap to trap (however briefly) and cause external corrosion damage. That said, inspecting piping could be very time consuming if wraps need to be removed, and some atmospheric dust would inevitably get trapped under the overwrap. We need some kind of CO2 sprayer to clean off the pipe before the wrap is fastened in place.
Perchlorates are known to be highly reactive with Iron at elevated temperatures. Pure Silicon will become violently reactive with perchlorates above 500C or so. While Silicon Nitride is exceptionally inert against pure salts, maybe not if the pipe's external surface temperature will exceeds500C, at which point those perchlorates are likely to start oxidizing a Nitride coating. This is an interesting materials problem. Given the presence of perchlorates in the abrasive blowing dust carried by the Martian atmosphere, I'd be curious to know what a close-to-optimal coatings solution entails if the pipe will carry salt heated to above 500C. Maybe we should ensure that temperatures are kept modest to avoid such a problem.
The problem with cheaper Alumina-based ceramic coatings is that those don't actually hold up very well, long-term, to hot salt. Uniform internal application to the pipe would also be rather difficult. Silicon Nitride does much better if the chemical attack involves salt and water. However, then there's this perchlorate problem to deal with on Mars. Even though the atmosphere is mostly CO2, the piping will be pelted with "oxy-dust", which will then become aggressively oxidative above a given temperature range. I need to think about application of different internal and external coatings. Now that I've given this some cursory thought, I don't think a single coating can be used.
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Underground geothermal storage works best for storage of relatively low grade heat, at temperatures low enough to avoid boiling groundwater and causing explosions. The low thermal conductivity of groundrock (1-5W/m.K) means that boreholes need to be close together. This increases upfront drilling cost. But unlike normal geothermal energy extraction, this is not heat mining because the heat is being stored and replenished. So the infrastructure does not face the same life limiting problems associated with hot dry rock geothermal. With the latter, once heat has been drained from an area, you have to move your power station because it takes millenia for conduction and radioactive decay to heat the local rock up again. If you are using the rock to store externally supplied energy, that limitation doesn't apply.
This kind of technology could have a number of applications. In situations where an industry needs a year round supply of relatively low grade heat, ~100°C, solar thermal infrastructure can charge this in the summer and the store allows heat to be used constantly throughout the year. That has a lot of potential applications. This technology really excels if we are prepared to make the investment in piped heating systems, i.e district heating. This is expensive to set up, but if done properly it will last for centuries. It is necessary because geothermal energy storage requires that heat be stored in a centralised volume. A piping system is therefore needed to distribute heat to dispersed consumers. A potential application for this technology is in small modular reactors providing waste heat for district heating. The reactors will operate 24/7/365. But heat demand is concentrated in the winter.
Another application is in solar assisted steam cycles. We build hybrid solar biomass/coal powerplants. In places away from the equator, the sun provides all of the energy to raise high quality steam in the summer, but cannot do so for the other 75% of the year. So we othersize the collector relative to the boilers. Heat is stored in boreholes at temperatures between 100 and 200°C. Outside of summer, stored heat is used to heat water between 100-200°C is a combined cycle boiler system. Coal or biomass provide the rest of the heating needed to provide high quality steam 300 - 400°C. Using the geothermal store, you get a power station that uses a combination of solar heat and fuel to provide baseload power. It is valuable, because biomass is a limited resource and it reduces CO2 emissions. We can use biomass as a fuel in the autumn and early winter and then switch to coal when biomass runs out in the spring and early summer. By using stored heat and leveraging fuel in this way, we get a baseload power source with reduced CO2 emissions and obviate the need to transport and store huge amounts of biomass.
Downsides: Every time you move heat you need a thermal gradient. The low thermal conductivity of the rock means that the heat source must be substantially hotter than the store. You end using higher grade heat to store lower grade heat. But maybe that is a hit you can afford to take. The other obvioys downside is that this is capital intensive infrastructure, that requires longterm investment horizons. Humanity needs to begin thinking in this way. We need to think of our grandchildren when we make investments.
Last edited by Calliban (2026-01-23 04:18:41)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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