Geothermal and Geothermal Battery (Changed Title 12/21/23)

tahanson43206 · 2023-03-14 18:47:15

For Void (and for the record) ...

My inquiry about the possibility of making a solid state energy harvester hit a roadblock today ... it was a human roadblock.

The manufacture of Seebeck devices I contacted responded to a Contact Form submission with a positive response, indicating that their devices are able to operate over a range from 160 Kelvin at the low end to 200 degrees Celsius at the high end. It is NOT necessary for Nitrogen to be cooled to liquid to perform the cooling function at 160 Kelvin.

I have reported elsewhere that it turns out that Nitrogen gas can be cooled to 160 Kelvin, where it would act as a heat sink for a bank of Seebeck devices. The pressure of such a system would rise to just about three atmospheres, where it would hold steady as cold gas is added and warm gas is drawn off.

While the top-of-the-line Seebeck devices from this manufacturer were rated at 5% efficiency in advertising, the company representative cut that back to 3%.

From my point of view, 3% of an infinite resource (the Earth's core) is 3% of infinite, so all I would have wanted to know is what the power output of the device would have been.

Unfortunately, the company rep decided not to pursue the matter further, citing as a reason the 3% efficiency.

Had the rep decided to pursue the matter further, I would have asked for performance that would be expected with a temperature difference between 160 Kelvin and 513 Kelvin. Whatever that amount would have been, it would have been inexhaustible on a human time scale.

It is disappointing to be slowed down with this particular manufacturer, but I am ever hopeful I'll find another manufacturer willing to pursue the matter further.

(th)

Calliban · 2023-03-15 04:05:23

Replacing the cable for a ropeway every six years adds up to a significant embodied energy cost. I decided to run the numbers. According to this site, the brickworks is 1.25 miles from the quarry.
https://www.lancastervision.com/oldest- … in-the-uk/

The cable is on a loop, so its total length is about 4000m. It is 1" or 2.54cm in diameter. Steel has a density of 7800kg/m3. From these numbers, I estimate the cable masses some 15.9 tonnes. Taking the embodied energy of steel to be 22MJ/kg, total embodied energy in the cable will be 350GJ. The cableway delivers 300 tonnes of mud each day. Over 6 years, that adds up to 657.5KT. That works out at 0.43MJ/tonne-mile, or 0.265MJ/tonne-km.

Wiki gives the energy intensity of UK rail freight as 0.4MJ/tonne-km.
https://en.m.wikipedia.org/wiki/Energy_ … _transport

So transport by ropeway has about two-thirds the energy cost of rail, which is already very efficient. Of course this is the value applicable to a gravity fed system. If hoists had to powered, then energy costs would be about the same.

I can see both advantages and limitations to ropeways. An obvious limitation is that they cannot operate safely in high winds. And high winds are not a rare occurance in the northern part of Britain. This ropeway is used over a relatively short distance. If we built these things to cover tens or hundreds of miles, then we have to replace a cable that is tens or hundreds of miles long every six years. A single point failure along the cable or hoists, would disable the whole route. In terms of labour, both rail and ropeway are comparable, as handling is needed at both ends. An obvious advantage to ropeways is that pylons can carry freight over land without bisecting it in the way a railway obviously would. But a ropeway may have difficulty passing under or over transmission lines. Energy cost is comparable to rail. But the distribution of cost is different. Both involve embodied energy in steel. For the railway, this is track. For the ropeway, it is the pylons and cable. Railways are usually diesel powered. Ropeway hoists may be electric, either from the grid or powered directly from PV panels or wind turbines. Or they would be direct mechanical wind powered or even gravity powered.

Like many ideas, it could be made to work. In a future world where liquid fuels are likely to be less available, it may become more applicable for freight in situations where a rail route would be too disruptive to the land it passes through.

Last edited by Calliban (2023-03-15 04:27:59)

Calliban · 2023-03-15 04:44:10

TH, this might be of use in your geothermal system if water is in short supply.
https://en.m.wikipedia.org/wiki/Heat_pipe

A heat pipe is essentially a sealed tube containing a heat transfer fluid that changes phase at the hot end. The phase change drives forced convection through the tube. The neat thing about this is that you don't need a pump. The heat transfer system out of the borehole is inherently simple. Your evaporator or steam generator can be located at the top of the well. At both ends, heat transfer is by conduction into and out of the tube.

If your design intends to pump liquid nitrogen down a well, then a seebeck device would appear unneccesary. High pressure nitrogen gas will be exiting the top of the well and you can extract power from it using a simple gas turbine expander. Pressure ratio should be excellent, which means high power density.

Using a trough solar thermal system and liquid air energy storage is an interesting combination. I wonder if compression heat can be recycled into the steam plant somehow? If solar heat is stored in deep boreholes and potential energy is stored in liquid air, then we have a mechanism that allows a solar thermal system to produce electricity in winter, when insolation levels are reduced.

Last edited by Calliban (2023-03-15 04:52:34)

Terraformer · 2023-03-15 05:18:42

Calliban,

Is that the value for recycled steel you used, or virgin? Presumably the old cable will be recycled.

[Copied to new thread]

tahanson43206 · 2023-03-15 06:29:59

For Calliban re #253

Thank you for that interesting idea, and for the link!

It occurs to me that a water based system may be using a similar system, if it is closed loop, because water can change to steam at the bottom of the well, and release energy back to water at the top.

A gas such as nitrogen need not necessarily change phase to be effective as a thermal energy transfer mechanism, but I agree that a phase change allows for more energy to be packed into a given volume of fluid, so in that sense the system would be more efficient.

I'll follow the link you provided, later today, to see what material is recommended.

An issue that came up during investigation of the feasibility of placing solid state devices at the well head is the rare elements currently used to make them. The supply of elements such as Tellurium is adequate to meet current demand, but a massive increase in demand would strain supply channels. I understand that Tellurium is obtained as a byproduct of copper mining.

SearchTerm:Phase Change as consideration for geothermal well design

Side note: I ran across an interesting hint that graphene may have Seebeck capabilities, and even a hint that the Seebeck coefficient might be superior to traditional metal configurations (as semiconductors) but I was unable to find anything beyond the hint. Graphene appears to be relatively new to humans, so there are probably properties that are not yet fully understood or documented.

Closing note .... The temperature available at the well head may guide designers in selecting a material for thermal energy recovery. Temperatures above the boiling point of water, combined with ready availability of water, might lead to selection of water as the most productive and cost effective solution.

On the other hand, temperatures below the boiling point of water, or total absence of water such as an arid desert or Mars, might lead the design team to selection of another material, based both on properties of the material and availability. For that reason, Carbon Dioxide might be a useful material on Mars for this purpose, despite the difficulty of working with it due to the narrow range between liquid and solid phases. It might be possible to design control equipment able to deliver CO2 as liquid at the top of the well at a temperature just above freezing. There is no danger of the material freezing after it enters the well, because temperature of the crust will start working immediately to convert the CO2 back to a gas.

Thanks again for this helpful addition to the topic!

(th)

tahanson43206 · 2023-03-15 06:51:33

This post is for Calliban regarding the suggestion of kbd512 to consider converting abandoned oil and gas wells to thermal energy harvesting.

When I asked Google about the dimensions of pipe that might be found in such wells, it came back with this snipped:

People also ask
How do you plug abandoned oil wells?
How wide is an oil well hole?
To drill a well, a specialized piece of equipment known as a drilling rig bores a hole through many layers of dirt and rock until it reaches the oil and gas reservoir where the oil is held. The size of the borehole differs from well to well, but is generally around 12.5 to 90 centimeters wide.
Oil well - Energy Education
energyeducation.ca › encyclopedia › Oil_well

It seems to me that one such pipe might be difficult to adapt for thermal energy harvest. However, if there are two such wells within some reasonable distance of each other, then it might be practical to use horizontal drilling to create a bridge between them. In ** that ** case, a fluid that is suitable for the purpose might be injected under pressure into one of the wells, and the heated fluid would be collected at the top.

As has been pointed out by sources cited by kbd512, the cost of drilling wells is removed from the investment, so return on the investment might occur within some reasonable time, even though the amount of energy collected is smaller than the original well(s) output.

(th)

Calliban · 2023-03-15 08:48:36

Sounds promissing, as the capital cost of the well has already been paid. I am assuming that direct heat applications will be a niche solution in the US, given that most wells will be in middle of nowhere.

The usefulness of the geothermal heat for production of electricity is a function of temperature. The condenser temperature of nuclear, coal or biomass steam plants is around 30°C, at which point the vapour pressure of water is about 70mbar or 0.07atm. If we produce steam at temperatures of around 100°C, then we could in principle generate electric power using a single stage LP turbine. But it may not be a desirable option, because the steam input to the turbine, fluid flow through the condenser and cooling towers, will be high relative to the power produced. That is another way of saying that the powerplant will be bulky and capital intensive per unit power. But the wells are free, so maybe a reduction in plant power density can be tolerated.

Another option would be to use geothermal heat as part of a hybrid powerplant. In this option, you could use geothermal heat to preheat feed water or develop a hybrid boiler, in which fuel provides low and high temperature heating and geothermal provides intermediate heating. This allows for a much more compact plant that raises superheated steam. But the geothermal heat can reduce the amount of fuel needed per unit steam. If geothermal heat can reduce fuel consumption by 30% say, then that would have a significant impact on its economics. In a world where fuel is expensive, any improvement to fuel economy could make a big difference to our ability to sustain our way of life.

Last edited by Calliban (2023-03-15 08:51:40)

tahanson43206 · 2023-03-15 10:18:00

For Calliban re #257

May I offer a follow up observation/question for your consideration?

The set up this my experience in the past day, of interaction with a (probably young) person who works for a well established firm based in the United States, which has as one of its many business lines a variety of Seebeck devices.

Our correspondence started with a contact form submission on the Division web site where Seebeck devices are a line of business.

To my surprise, a company representative replied, with the information that the bottom temperature tolerated by their devices is 160 Kelvin, well above the temperature of LN2 at 77 K.

I replied, with explanation of the intended application, and I asked for confirmation the representative was willing to pursue the line of inquiry. I am well aware of the importance of establishing and maintaining a reputation within a company, and especially when the representative is in a public facing position. Therefore, I was disappointed but not surprised when the representative declined the opportunity to proceed. All correspondence was copied to a person who I am guessing was the immediate superior.

To have pursued the question further might well have looked risky to the representative, so the decision was made to withdraw from further contact.

However, you are much better situated to consider the objection posed by the company representative. In the closing email, the statement was made that because the company devices are only about 3% efficient, the geothermal well application did not look feasible.

If NASA had been the customer and the heat source was an RTG headed to deep space, the 3% performance would have been a starting point for further discussion.

In the case of a geothermal well, the Earth itself is a gigantic RTG. Had this (probably young) person been able to make that connection, then the issue of 3% of infinite would have shown that the issue of efficiency is irrelevant.

The ONLY question that mattered in the context of a geothermal RTG power delivery system is how MUCH current can one of their devices deliver. The temperature range available is potentially from 77 K to 513 K. The actual devices operate over a range with a higher low point, and a higher upper point. There is considerable overlap between the two. i'd have been ** really ** interested to know what the devices on the market today can actually produce, under the conditions described.

We will never get a chance to find out from that particular manufacturer.

However, I've approached another manufacturer, and if they respond to my inquiry, I will take care to cast the question in what I hope will be a non-threatening context, of a heat making plant located four kilometers from the location where the energy is to be collected. I will explain that 3% efficiency is NOT a concern, because ALL the heat is going to waste at present.

So! Now! Here is a question for you ...

A Seebeck device is a bit of quantum physics that allows a randomly bouncing molecule to cause an electron at an interface to move in a direction through an external circuit. I suspect this process is NOT subject to Carnot, which is a rule for randomly moving objects. The Seebeck device can be better understood as a one-way valve, such as a vacuum tube rectifier or the modern semiconductor equivalent. Carnot does NOT govern movement of electrons from one energy state to another inside an atom. I suspect (but do not KNOW) the Seebeck behavior is governed by Quantum Physics.

A Seebeck device could be packaged as a tiny battery, that would travel down a pipe to a geothermal well head, where external thermal energy would act to pump one or more electrons to an elevated state inside the tiny battery, at which point the package would return to the surface where (through some miracle) the stored charge could be drained off into an external circuit.

As you evaluate this scenario, from the viewpoint of one well versed in Carnot, can you see any problem or issue that might be escaping my attention?

To restate my understanding of the situation...

A piston is a mechanism for translating random motion (of a great number of molecules) into unidirectional motion. A piston is governed by Carnot.

A tiny Seebeck battery would translate random motion of an individual molecule into a quantum movement of an individual electron, from a lower state to a higher one, where the energy received from the random molecule is stored as an energy state to be released later.

I suspect the low efficiency of conversion of thermal energy to electrical current observed to date in Seebeck devices is due to our currently limited human understanding of the physics involved.

In a completely different context, the heating we observe when a space craft returns from orbit is caused by the wildly undisciplined behavior of air molecules that are pushed out of the way of the oncoming heat shield. Obviously to this point humans have no idea how to prevent undisciplined behavior of air molecules when disturbed in this way.

The ** one ** example of human ingenuity applied to the problem is the British Skylon system, which seeks to discipline air molecules by cooling them with liquid hydrogen. More accurately, it might be more appropriate to say that the undisciplined random motion of the air molecules who were rudely accelerated by the oncoming spacecraft is subdued by transferring their agitation to the previously cool hydrogen molecules. I am looking for a solution that prevents air molecules from bouncing away in the first place. it is the elastic bounces of those air molecules that generate photons that accumulate in the form of visible light and infrared photons.

All that is needed for a space craft to decelerate when entering an atmosphere is to transfer momentum to a number of air (or atmosphere) molecules. When a sufficient amount of momentum has been transferred to the resident molecules, they can be released to go about their business.

I recognize that all of that last section of the post would better fit in another topic.

(th)

Calliban · 2023-03-15 14:03:56

TH, I am not a physicist and no expect on quantum mechanics. So I cannot comment on whether the 3% present day efficiency of a Seebeck device is something we might improve upon with time. But I do know that to produce a potential difference with such a device, there has to be a temperature gradient across it. The 3% efficiency is the ratio between electric power produced to thermal power conducting across the device. A larger thermal gradient would result in a higher heat flux and more power out. There are a few ultimate limitations to the power density of such a device. The most obvious is melting point. No part of the device can reach a temperature above its own melting point. The second is thermal shock. If one part of the device is hotter than another, its thermal expansion will be greater than the colder part. If the difference is too great, then shearing stresses will cause fractures to grow. If one part of the device is extremely cold, then it will also be brittle, reducing the critical crack length. Some materials are more susceptable than others. Finally, electrical conductivity declines as metal temperature increases.

The total energy supply available from a geothermal well is indeed almost infinite. But power is not. Power is the flowrate of energy from the surrounding rock into your device. Before you first switch it on, the rocks around it will be in equilibrium temperature, with the same amount of heat flowing into each piece of rock as is leaving. But as soon as you start extracting energy, you create a temperature gradient. This gradient gets shallower and shallower as you drain more heat out of the rock. And to get more heat into the device, you have to conduct through a progressively thicker layer of rock as the gradient shallows. We could in fact establish thermal equilibrium, in which temperature gradient remains constant once established. If we could do that, we could continue extracting power at the same rate for as long as the well lining lasts. But the problem here is that rock is not a particularly good conductor because it is ceramic. Thermal conductivity is 1-5W/m.K at room temperature. To get a reasonable power output from your equipment, you must move on to a new site once heat has been drained from the rock. So geothermal power tends to be 'heat mining'. It really has to be this way, because your equipment has its own embodied energy and a limited operating life. If power output is too low, the machines cannot repay their own energy investment before they wear out.

Coming back to the 3% efficiency. If the heat flux is limited by temperature gradient and total resource at a site is limited due to thermal conductivity, then useful energy output over equipment lifetime, is directly proportional to electrical conversion efficiency. A lower efficiency means lower return on invested capital, all else being equal. You might be able to remove some equipment and shift it to another site when the present one is exhausted. But most of the invested equipment will be scrap. And you cannot reuse the sunk labour cost of assembling the equipment. Very few machines have useful life more than a few decades and the well lining itself has a limited life expectancy. So there is little point withdrawing heat at a rate that extends the useful life of the site beyond that of the plant. The return on capital will be greatest if heat is withdrawn at a rate that balances the life of the site with equipment life expectancy, which is 20-40 years.

So conversion efficiency of geothermal heat into electricity is very important. This is why we are unlikely to use Seebeck devices in geothermal wells. On a spacecraft, we have very different design goals. We need relatively small amounts of power to be sustained for decades. The system needs to be extremely reliable, because no one can repair it a billion miles from Earth. We have radioisotopes with huge energy density. And cost and net energy return are less important, because we can afford to invest millions of dollars per kW of power. So a Seebeck device is the right design choice. Likely, the RTG will never return the energy needed to create it.

Last edited by Calliban (2023-03-15 14:17:32)

SpaceNut · 2023-03-15 17:47:32

Reposting information

Calliban wrote:

Hybrid powerplants are another thing to add to the mix of options.
https://www.sciencedirect.com/science/a … 7X14000057
Typically, this involves using solar heat to preheat boiler feed water. But we could build hybrid boilers, in which coal or biomass provide input to the superheater and economizer sections and concentrated solar contributes intermediate heat. In this way, you get to produce superheated steam, have an efficiency of >40% and a 90% capacity factor on the powerplant. But the contribution from the solar (or geothermal) heat reduces the amount of fuel burned, by up to 50%. That reduces CO2 emissions and allows the powerplant to remain proffitable with more expensive fuel.
Another option would be to incorporate thermal storage into a thermodynamic plant. If wind power is producing a lot of excess, we activate heating elements in a molten salt tank. The molten salt then provides intermediate level heat to the boiler, reducing coal or biomass consumption. In the UK, solar power is weak and highly seasonal. A hybrid plant incorporating a molten salt energy store, could use solar trough heat in late spring, summer and early autumn and absorb excess wind electricity in the winter months. The downside of this type of thermal storage is that you only get at most 40% of the input electricity back as output electricity. That is less wasteful if you can use the condenser heat for district heating. A hybrid could in principle use a flexible fuel approach. Biomass is seasonal and storing it for long periods is difficult, because fungus grows on it when it is damp. Biomass will be most readily available in autumn and winter. So we want a hybrid plant with mills capable of grinding biomass when available and coal when it is not.
If we can build a thermal powerplant, in which solar thermal, wind electricity, biomass and coal each contribute one quarter of thermal energy, then we have reduced coal consumption and CO2 emissions by 75%. If we can use the waste heat that comes out of the condenser for district heating, then overall fossil fuel energy consumption is reduced by 85% relative to baseline. In the future we don't neccesarily have to stop using fossil fuels entirely. We just need to use less that we do now.
A hybrid would work best if all elements of it were integrated on the same site. The solar troughs obviously have to be built close to the thermal store. But there are lots of other things worth taking advantage of. Wind and solar power can be used to carry out feed water treatment for the plant. Feed water can be stored, so intermittency in water treatment can be tolerated. We could also use solar or geothermal power to preheat feed water. The feed pumps themselves could be driven by compressed air that is provided by mechanical wind turbines. The condenser extraction pumps and the mills could be air powered or hydraullically powered as well. The hydrogen used to lubricate and cool the alternator could be generated from intermittent energy sources. There are lots of ways in which parasitic loads can be met using stored intermittent energy. If we can do this, we can increase the net power output of the steam plant another 10%, as the plant no longer has to use its own electrical output to meet internal loads. If our thermodynamic plant can be colocated with a wind farm, then both can make use of the same step up transformers and switch house. If wind turbines are hydraulic, then we could even mount a hydraulic turbine on the same shaft as the steam turbine. That allows a single alternator to serve both the steam powerplant and the wind farm.

I do agree with the thoughts to combine energy sources of heat into a single purpose.

tahanson43206 · 2023-03-16 07:02:20

Re #259 for Calliban...

Thank you for your detailed evaluation of the ideas in discussion recently. This post is reserved for a reply when there is time to study #259 carefully.

(th)

tahanson43206 · 2023-03-16 07:23:40

For Calliban re #259 (after returning from posting about antimatter in another topic)

The point you made, (not for the first time) of the risk of exhausting the supply of thermal energy from a well head at 4 kilometers below the surface is interesting and it deserves experimental data to confirm or falsify. However, ** this ** post is about something completely different, where the supply of renewed thermal energy is practically inexhaustible.

The ocean is a repository of thermal energy, and it allows for circulation so that if energy is drawn from a volume, a supply of warmer water will arrive shortly to replenish the stock.

I've been trying to solve the OTEC baryon problem since I first heard about it, and the recent contribution by kbd512, of the idea of using LN2 for an energy management system of some kind has led to the insight that cold gas can serve as the cold sink for thermoelectric devices.

Your observations about possible exhaustion of thermal energy at the base of geothermal wells which are NOT bathed in water suggests placing such wells where water is abundant, and the oceans are places where water is abundant.

What is more, at the present time in Earth's history, there is more thermal energy in the oceans than is good for the planet.

A system of energy harvesting that draws thermal energy from the Earth's oceans would be regarded as a "good thing" by many, and (hopefully) not a concern to others.

The Seebeck devices are only 3% or so efficient, although I have seen reports that NASA has achieved 17% in the lab. The actual efficiency is of absolutely no consequence that I can see, if the system pulls energy from an inexhaustible source of energy.

However, that said, I still need to allocate time to study your post carefully, to try to understand why efficiency is an issue. It may be. I just don't see it yet.

To my way of thinking, 3% of infinite is still infinite. But I could be missing something important, so look forward to study of your post later today (hopefully)

(th)

SpaceNut · 2023-03-18 20:43:47

The question keeps bugging me as I know that we use energy in a non-average mode all the time and that due to the grid and how others are using their own we end up with a more stable with peak loading on the grid.

How Many kWh Per Day Is Normal? Average 1-6 Person Home kWh Usage

Here is the total US residential electricity consumption of 118.2 million US homes:
All in all, we use 1,267 billion kWh of electricity per year. The total cost of this electricity is $219.34 billion annually.
We spend 214.2 billion kWh (16.9%) on air conditioning.
We spend 186.9 billion kWh (14.8%) on space heating (usually on heat pumps).
average home will use 10,720 kWh of electricity per year. That comes to 893.33 kWh per month, 205.59 kWh per week and, finally, 29.37 kWh per day

I just got my electrical bill and my daily use for the last month was double the above with just an electric heater to keep the home at 55 to 60 F. Normally its down near that amount when warm as we do not use AC just fans.

This accounts for no energy for a vehicle or other concerns in which we might want some for use.

Of course, a solar thermal and storage would change that but still not all would be solved.

From a solar panel energy provider How Many KWh Does A House Use Per Day: Ultimate Guide
Numbers that raise a question for what is average... Meaning that the real energy is most likely higher.

Other things to consider are not all homes are of equal insulative quality and not all homes see the same cold or heat of the seasons.

Also, since cars would need to be all electrical to get a real total and all I have is the hybrid and gasoline to make use of then let's see if we convert to a gas source for the electrical how that will look.

Conversion: Kilowatt Hour to Gasoline Gallon Equivalent with numbers that if I feed that little amount of gas into a generator would fail to produce the electrical one would get.

1 kWh = 0.029678483099753 gge

Most references on how much gasoline a generator uses report averages of three-quarters a gallon per hour at normal load.
So if we look for a generator that produces 2kw then we have the bare minimum looks like 4 hrs on a gallon. Which is a far cry from a 24 hr clock and then you need several of them to allow for cool down cycles so as to not destroy them.

24 hr x 1.5 kw = 36kwhr daily required at $4 a gallon x 6 for the day = $24 a day... 30 day average = $720 a month ouch as that is really high an add to that the vehicle which is $60 a week brings the fuel cost to $960 for everything.

Sure, other fuel types will be just different numbers, but they are still too high...

tahanson43206 · 2023-03-19 06:11:42

For SpaceNut re #263

Thanks for that analysis of electrical usage and gasoline equivalent costs!

SearchTerm:gasoline equivalent gallon (Gasiline Gallon Equivalent) (gge)

SpaceNut reviews average power usage and calculates gasoline costs

(th)

SpaceNut · 2023-03-20 19:07:59

Since I have no other heat source other than electrical and seeing a bill that indicates that I used 1,600 kwhr in a month up from no heat that normally would be under 750kwhr shows just how far off the numbers are for what the quote indicated for the AC or heating power uses.

Calliban · 2023-03-21 00:30:43

SpaceNut, this might be of use to you:
https://www.stovesellers.com/ena0-5/enn … -mamy.html

My stove does about half of my space heating. I scavenge about half of the fuel I use. With the right set up, a range could do your cooking, space and water heating. Even if you have to buy wood, it will be cheaper than electricity for heating. But there are places you can get waste wood from. Pallets are good for burning, especially if you have a bandsaw to chop them up. In my house, any waste paper and cardboard packaging gets burned as well. I sometimes burn garden waste like twigs and dry grass. If I go for a walk with the dog, I will try and gather a few bits of wood as I do it. I also take the car round to business estates and collect old pallets and waste wood that they have put out for trash. I live close to the sea, so drift wood us a source of fuel for me as well. I try and build up a few cubic metres of wood in this way for winter. I buy in some more, usually kiln dried oak. I draw the line at plastics. Burning plastics just isn't responsible from an air quality perspective.

TH will probably say something along the lines of this board being used to develop general solutions applicable for everyone. However, the right solution will always depend upon where you live and what your specific circumstances are. If you want small supplemental heating that can reduce your gas or electricity bill then wood is a fairly easy solution. It is cheap in cash is you are able to scavenge, though that will cost you time. We cannot power the entire world this way. But if something can provide 10% of a solution, then 10% is still 10%. If you scavenge, then most of what you burn is either heading for land fill or would otherwise rot. So you are explouting something that will otherwise go to waste.

If you have plenty of back garden space, then a ground source heat pump might work for you. My parents are looking to get one installed, but their ground conditions are not ideal. I live in a town and am on the gas network. I don't have enough space for ground source and air source is poorly efficient solution, not much better than resistance heaters and more expensive to install. But I am thinking of running an air source heat pump through a thermal capacitance, like a big water tank.

I am planning to move and have enough money to buy a place with some acres. My wife, children and I live in the north of England. The places we are looking to move to are out in the sticks, a long way from anywhere. We probably won't have gas. If that turns out to be the case, I will probably install a ground source heat pump. I like the idea of interseasonal storage of solar heat. But that would involve quite a lot of digging and ground insulation. I will look into that depending upon what the circumstances happen to be.

Last edited by Calliban (2023-03-21 00:56:34)

SpaceNut · 2023-03-21 19:28:36

I was reminded by the images on the link of the old cook stove that my very old grand mother had when I was a teenager in the 70's.

My son up north has been using a pellet stove to heat with for several years and replaced the other one that he had this year the level of tons has been 4 to 5 tons. This equates to pallets that are 50 lbs bags that are 4x4 x 5 ft tall. Of course, these require a stove fan to push the heat out of the unit and the ceiling fans to push that heat back downward where it will do some good. The cellar has an oil boiler furnace that does the hot water as well and it requires several hundred gallons to make things not freeze and to provide the much-needed water for showers of course.

For dried cut split logs most, homes have a similar number of cods to be made of that are 4x4 x 8ft long as tons or pallets. The cost is controlled by manual labor both in the logging and splitting to set them out to be able to dry for each yearly use. Green wood purchase is always cheaper, but it comes with its own set of issues. The delivery sometimes will go up from what you would expect they need to recover fuel charge and that means if you need to travel further it's going to cost you.

here is an example site.
https://heafieldlandscaping.com/cord-wood-for-sale-nh/

o if we couple the heat from wood burning to a boiler or storage that make sense and combination it will solar concentrated heat. I should be able to lower the cost but keep the heat level up. It would mean building from scratch and making a custom system for the purpose.

SpaceNut · 2023-03-26 12:28:08

We take so much from mother earth that is free and we want a NewMars to be the same where we breath the air and drink water with next to nothing for energy to be expended to make them available.
Short of making Nuclear source to scale for a residential use we are stuck with many a source that has low efficiencies to create and then store.

MY $300 DIY 12-VOLT CAMPERVAN HOT WATER HEATER

Calliban · 2023-03-26 14:18:35

SpaceNut wrote:

We take so much from mother earth that is free and we want a NewMars to be the same where we breath the air and drink water with next to nothing for energy to be expended to make them available.
Short of making Nuclear source to scale for a residential use we are stuck with many a source that has low efficiencies to create and then store.

Indeed. I think future Marzies will look back at Earth and marvel at a place that has vast open expanses full of free air. Pure water that falls for free from the sky. Places that are warm enough to walk around in without thick clothing. Soil that is fertile and will grow stuff out in the open, without any pressure dome keeping it alive. Giant oceans of water that are often warm enough to swim in, containing food that you can fish out and eat. How bounteous the Earth really is! A space alien may think it odd that we human beings are spending billions in an attempt to leave a virtual paradise, and travel to a place that is cold, barren, airless, lifeless and bathed in hard radiation. Most creatures would not bother. It takes some serious conviction and patience to go to a place like that and imagine what it could be with enough work.

The cold is going to be a big problem. Average temperature is about -60°C. And it is extremely cold everywhere at night. Even if radiation weren't a problem, I think we will end up living underground to get away from the cold. Humans could adapt to living underground. We have talked about ways that could work. The real problem is going to be food. Growing enough food on a planet with virtually no atmospheric pressure, where it gets to -90°C at night, is going to be a real challenge. Everything must be grown in a pressure dome, which will be expensive. Any greenhouse must be either super insulated at night, or heated. There are places where we might find geothermal heat on Mars. But most places are going to need nuclear reactors to produce heat and power.

One of the reasons I keep banging on about microalgae is that it can be grown in compact tubes and drained into a storage tank overnight, before temperatures start to drop. It is one of the few things that might be grown without supplemental heating on Mars. But turning it into food that is both nutritionally balanced and palatable to humans, is a real challenge. Growing food on Mars will be a science all of its own. If we can produce cheap and abundant food, that is also nutritious and palatable, then we are already half way to creating a viable civilisation on Mars.

Last edited by Calliban (2023-03-26 14:25:36)

SpaceNut · 2023-04-05 21:51:00

Texas geothermal startup is storing energy in the ground

south of San Isidro, a tiny Texas town near the U.S.-Mexico border, an abandoned gas exploration well is once again being put to work. A 10-foot wellhead rises from a dusty square lot that sits on a 500-acre cattle ranch. Last year, the company created a 3,200-foot vertical reservoir deep underground using its novel fracturing technology. For the last six weeks, Sage has been pumping and storing large volumes of water in the artificial reservoir, which sits in the rock formation at an average depth of 9,500 feet.
The startup is also seeking to deploy the same approach in deeper and hotter geothermal wells — of temperatures exceeding 300 degrees Fahrenheit — where it believes the cost-effective combination of pressure and heat can deliver potentially two times more energy than pressure alone.
The startup installed a ground-level storage facility that holds some 30,000 barrels (1.26 million gallons) of water, the source for which is a nearby private water well. Sage pumps water into the fracture in various volumes and measures the water’s flow rate — or how many barrels are moving through the well per minute. Computer models use the data gathered during testing to simulate how much electricity the site could discharge, like a battery, over certain periods of time.
“The results are so much more than we anticipated,” Taff said by phone last week.
Early tests suggest that, by pumping 5,000 barrels of water into the well, the site could produce 200 kilowatts of electricity during a 5-hour stretch. With 10,000 barrels, the site could produce the same amount of power for 9 hours. A later round of testing indicated that pumping some 20,000 barrels of water could generate 650 kilowatts of electricity for 2 hours.
0.4 percent of annual U.S. electricity generation comes from geothermal power plants, the bulk of which are located in California and Nevada. Wind and solar projects, by contrast, account for 10.2 percent and 3.4 percent, respectively, and are more widely distributed across the country.
Fervo Energy, another Houston-based startup, is using the same horizontal drilling techniques and fiber-optic sensing tools as the oil and gas industry to develop lower-cost geothermal power. Its first commercial plant, a 5-megawatt facility, is now under construction in Nevada.

edit reminder from page 1

Void · 2023-04-06 09:04:07

That's a little different. Pressurized water. I will bet that there are lots of air bubbles and air pockets in the fracked volume, and so that can make it possible to push water into it. Also the ground may tend to flex a bit I would think.

Interesting stuff.

Done.

SpaceNut · 2023-04-09 14:29:26

I built from 2" pcv pipe a site location device to further location and collection time.

10am its just barely hitting the location and by 2pm its in shadow once more.

as its just 90' of solar sweep that can be gotten.

tahanson43206 · 2023-04-09 20:00:28

For SpaceNut .... were you thinking of capturing solar energy to be stored as geothermal/geostored energy?

If not your recent work with solar might fit nicely into a topic about solar power.

(th)

SpaceNut · 2023-04-18 23:48:56

I am looking to collect the energy but also to see if I can create energy from it as well. I also need to think about when water is used in the other half of the year that nightly freeze protection will be required in the collector. I might be able to do a dual working fluid system in the same unit with seperate tubing to carry them with in it such that during winter cold the water is drained back out of its loop through the collector.
The water system would be to make energy via steam hopefully while the other would be to store the heat.

SpaceNut · 2023-04-23 13:59:41

https://www.osti.gov/etdeweb/servlets/purl/894040
GEOTHERMAL POWER GENERATION
A PRIMER ON LOW-TEMPERATURE, SMALL-SCALE APPLICATIONS

https://www.energy.gov/sites/prod/files … atpump.pdf

https://www.sciencedirect.com/topics/en … nary-cycle

edit update from thermal battery for a car topic

The making of the heat storage and exchanger assembly with the converting elements are going to be literally dependent on the space allotment that we might make use of for the distance efficiency that we might be able to achieve.

One could imagine the co2 in the tubing with the limestone poured around inside the tank.
attachment.php?attachmentid=1349231&stc=1&d=1455899261

Of course, if we only have a square or rectangular area to make use of it we might need to change the method of the tank and exchanging methods.

You can think of a heat exchange and storage combination as having a transformer like winding function..

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