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#126 2023-06-13 20:53:58

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

Ya cooling is required versus heating so I can see the short term no action much like the water situation when it's raining.

Surprising graph shows the unexpected way many Americans are heating their homes: ‘[It] will take off even further’

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#127 2023-06-28 04:04:31

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

This article discusses a community based cooking scheme in the Netherlands.  The guiding idea is that cooking is more efficient when centralized, i.e. cooking for hundreds of people uses far less energy per capita than cooking for one person.
https://www.humanpowerplant.be/2020/06/the-fire.html

The Dutch concept burns biomass in a centralized community cooker to produce all of the cooked food for a community.
https://en.wikipedia.org/wiki/Low-temperature_cooking

The idea of low temperature cooking does not seem to have occurred to them.  This involves slowly cooking at temperatures <100C, often over a period of days.  Meats can be safely cooked at temperatures above 68C, which kills bacteria.  Vegetables require temperatures of around 80C to soften.  Temperatures in this range could be achieved using heat pumps with COP around 3.  There are crystalline paraffin waxes that melt between 70-85C, which could function as phase change materials, storing large quantities of heat at specific temperatures.

A community equipped with a centralized low-temperature cooker could therefore cook using intermittent energy, provided by electricity, mechanical power or concentrated solar heat.  A large cooker could be insulated by housing it in a deep pit, which would allow it to remain at constant temperature for many months without additional heating.  This is definitely something that individual towns or city districts could build.  But it requires that citizens cooperate and pool resources into developing community infrastructure.

If European countries lose access to natural gas and reliable electricity, low temperature community cooking is something we could use at a district level.  The heat pump supplying the heat could be a positive displacement compressor, directly driven by a wind turbine shaft.  Such a device could be mechanically very simple.  It is even possible to imagine arrangements where a single heat pump provides cooling to a community freezer at -20C and heat to a low temperature cooker at 80C.

Last edited by Calliban (2023-06-28 06:13:49)


"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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#128 2023-06-28 09:46:37

tahanson43206
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Registered: 2018-04-27
Posts: 18,131

Re: Thermal Energy Storage

For Calliban re #127

Thanks for the link to the report on the Dutch community that is organized to use an ancient heating method in an efficient way.

The idea of operating bellows through an exercise program is quite interesting.

What must have seemed like drudgery to our ancestors is recast in the modern light as a way to stay in shape.

Obviously, (or at least I ** think ** it's obvious) this concept wouldn't work well on Mars.

What I think remains to be seen is whether the second generation are going to support this idea.  The Amish (apparently) have a exit option for young folks raised in their system. Apparently a great number choose to keep the old traditions going, or at least ** enough ** do so to the population remains stable despite losses.

Your low temperature ideas are interesting as well, and it seems to me worth anyone noting the option.  I am wary of the idea, and would never seriously consider it, having been raised in a time when safe cooking temperatures are drilled into the population.  However, I'll be interested if you can find examples of individuals who have successfully employed the technique.

That said, I am ** very ** happy with all-day slow cooking, which produces savory results day after day, year after year, without a lot of attention needed.

All in all, I am in favor of organizing ourselves to enjoy an abundance of energy, and be able to forget about the bad old days of energy paucity.

In your writings, you seem (to my eye anyway) to swing between extremes of pessimism and optimism, with the mean toward the lower end of the scale.

(th)

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#129 2023-06-30 06:16:11

tahanson43206
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Posts: 18,131

Re: Thermal Energy Storage

June 30th Earthside ...

tahanson43206 wrote:

for Terraformer...

It's been a while since I inquired about developments in your initiative with the government official.

Hopefully work is underway.

(th)

tahanson43206 wrote:

For Terraformer re "Quick" response from government official....

http://newmars.com/forums/viewtopic.php … 76#p206676

A month has gone by .... I'm hoping you have time to follow up with your contact, to see what has happened.

I am doubtful anything is going to happen in your community unless you are there to poke and prod and move things along.

There appear to be generous allocations of national wealth available for communities to apply toward goals judged worthy.

For a goal to be judged worthy, it seems to me a presentation is required, and that requires a presenter, and a presenter needs a support team.

It seems to me that this forum is good for banter about possibilities, but for anything to happen in the Real Universe, it is necessary to apply pressure ON the Real Universe.

(th)

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#130 2023-09-06 05:32:06

Terraformer
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From: The Fortunate Isles
Registered: 2007-08-27
Posts: 3,857
Website

Re: Thermal Energy Storage

Hmm. Barium Hydroxide has a melting point of 78c and a latent heat of 655MJ/m^3 (181 kWh). If that was connected to a heat sink at 10c, we might be able to extract about 14% of that as work (19.4% carnot efficiency; as far as I've been able to find out, our best heat engines achieve ~75% of theoretical maximum), so 25 kWh per cubic metre. 25 Wh per litre; ~10 Wh per kg. Worse than even nickel-iron, but hey, those temperatures are achievable with really simple solar collectors.

There may be better materials of course... lighter materials. This is roughly on par with hot water as far as energy density is concerned.

Other materials: paraffin wax can melt at 340K and store 200kJ (55 Wh) per kg. Of which we might extract 5 Wh... hmph. Far worse than hot water and more expensive. The advantage of phase change materials is constant temperature, but that isn't such an issue when the storage medium is liquid and you can take what you need and leave the rest at the same temperature. Water at 97c/370 with a heat sink at 300K could get 15% efficiency too and give us 12 Wh per kg with a simpler system. About a third of what lead-acid gives, but if you're after something that you can build and maintain yourself it's a better option, and with the solar collector being at least 3x as efficient as solar PV collectors it evens out.

(Yes, I know all these calculations have been done back in the thread, but I don't wish to search through them and I like working through things for myself.)


Use what is abundant and build to last

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#131 2023-09-06 08:40:57

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

If the waste heat can be used for something valuable, like district heating, then efficiency matters less.  In a country like UK, we could build a solar thermal plant outside of a town.  When it is sunny, it would generate steam at say 200°C, which would be dried and would enter an MP turbine, generating electric power.  We could collect condenser water at 30-100°C and store it in a big, insulated tank.  Come winter, we pump it around town in a district heating network.

Last edited by Calliban (2023-09-06 08:42:01)


"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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#132 2023-09-06 09:44:57

tahanson43206
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Posts: 18,131

Re: Thermal Energy Storage

For Calliban re #131

I don't know what "drying" steams means, in your post.

My choices are: Google or just ask you ...

Asking you has the distinct advantage of giving you feedback that your post was read by at least one person.

(th)

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#133 2023-09-06 10:17:56

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

tahanson43206 wrote:

For Calliban re #131

I don't know what "drying" steams means, in your post.

My choices are: Google or just ask you ...

Asking you has the distinct advantage of giving you feedback that your post was read by at least one person.

(th)

Unless the steam is superheated to a temperature above the critical temperature of water (374°C), it will consist of a mixture of water vapour (gas) and liquid droplets.  This is wet steam.  Dry steam is pure H2O gas.  If you attempt to put wet steam into a turbine, whose blade tip speed is usually supersonic, collision with water droplets will destroy the blades.  So boilers have steam dryers mounted on top of them.  These introduce vorticity, creating centrifugal force which removes the water droplets from the steam.  The dry steam can then enter the turbine.  Most coal burning plants have superheaters that take the steam up 500°C.  Steam at this temperature does not need to be dried, as it is above the critical point of water.

Last edited by Calliban (2023-09-06 10:20:41)


"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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#134 2023-09-06 10:44:54

tahanson43206
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Registered: 2018-04-27
Posts: 18,131

Re: Thermal Energy Storage

For Calliban re #133

Thank you for the explanation of the concept of "dry" steam.

SearchTerm:steam dry explanation of

This topic is "Thermal Energy Storage" so I am at risk of departing from the theme with this observation...

Mars is shy of water, but has an abundance of carbon dioxide ... I asked Google if there is such a thing as a turbine that runs on hot carbon dioxide gas, and it found a citation of Toshiba having developed such a device.  I'll add to this post from the computer where I found the citation. 

***
I asked Google if there is such a thing as a gas turbine that runs on hot carbon dioxide gas, and if found one ...

I note that Google is now including AI in their process...

Generative AI is experimental. Info quality may vary.
Yes, there are gas turbines that run on hot carbon dioxide gas. These turbines use supercritical carbon dioxide, which is kept at high pressure and temperature. The carbon dioxide is in a state between a gas and a liquid, allowing the turbine to generate power.
The Japanese company Toshiba developed a gas turbine that uses CO2 gas produced at 1150°C and 300 bar. Echogen Power Systems in Akron, Ohio designed an 8-MW generator that uses supercritical CO2 to turn waste heat into electricity. The process produces about 20% more power than a gas turbine alone.
Supercritical carbon dioxide is easier to compress than steam. This allows a generator to extract power from a turbine at higher temperatures. The result is a turbine that can be 10 times smaller than a steam turbine.

Back to Calliban ... given the above, it would appear (to me at least) as though a small nuclear reactor is the best choice for a heat source for Mars.  There is plenty of CO2.  The gas would have to be cleaned up for use in the system described above, but once it is ready for use, I would imagine it could be kept in a closed loop for an extended period.

There might be issues with valves and seals?

I note that the gas turbine using CO2 has come up in the forum previously.

(th)

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#135 2023-09-07 05:11:49

Spaniard
Member
From: Spain
Registered: 2008-04-18
Posts: 133

Re: Thermal Energy Storage

I think that multiple source is better than one unique energy source.

If the mission is just go and return, certainly a closed nuclear reactor, with minimal maintenance is probably the most practical. But if a minimal IRSU is gonna be developed, a nuclear reactor is too complex. Only some replacements, specially fuel, can be considered. The rest would be imported.

Solar thermal with parabolic mirrors should be easy enough to manufacture on Mars. The low temperature of the cold side of the thermodynamic extraction should be do it even more efficient than on Earth. Not very high temperature needed, even if the concentration allows it. I guess regular salt storage could be enough.

For long term storage, CO2 liquefaction could work well for cheap and easy manufacture.

The nuclear reactor should be enough for essential energy needs, while regular solar allows to boots to exceeded energy production.
Something like.

Essential.

Life support. CO2-O2 purification + Thermal regulation on "save energy" mode + basic systems (essential communication, greenhouse, etc.) + Minimal H2O extraction... etc.

Secondary

Vehicle recharge. Fuel generation. Thermal up to comfort level. H2O in regular use (not rationed like essential mode).

Extra

Generation excess. Safety margins. Extra storage in energy, fuel, water, etc.

It's only needed that nuclear cover the essential. Everything else could be covered using IRSU.

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#136 2023-09-07 08:38:56

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

Cryogenic energy involves the production of liquid nitrogen or liquid air in a shore side refrigeration plant.  The LN2 or LAir is then pumped or drained into propellant tanks onboard the ship.  The ship raises power by evaporating the liquefied N2 or air within a boiler and passing the high pressure gas through a turbine.  At least a few researchers are looking into this idea.
https://maritime-executive.com/editoria … propulsion

The problem is energy density.  One kg of diesel contains about 43MJ of thermal energy.  About 20MJ of this can be extracted as work by diesel engines.  By contrast, the amount of potential energy yielded by liquid nitrogen is 0.349MJ/kg.  That is 57x lower per unit mass and 45x lower on a volume basis.  So liquid air would take up much more volume than diesel.
https://en.m.wikipedia.org/wiki/Energy_ … ence_Table

I think the best approach would be a hybrid drive system.  The ship would carry both diesel and liquid nitrogen engines.  The ship would make use of the waste heat from the diesel engines to evaporate the LN2. This would boost the efficiency of energy recovery from the N2.  The extra power from the N2 would cut the diesel consumption of the ship by as much as one half.  This would allow freight ships to take more direct routes to their destinations, avoiding the need for refuelling stops.  It also makes sea freight less sensitive to oil price spikes and shortages.  Whilst LN2 would not eliminate marine fuel consumption, it could reduce fuel consumption considerably.

Last edited by Calliban (2023-09-07 08:54:00)


"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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#137 2023-12-30 18:45:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

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#138 2023-12-31 12:39:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

Beneath Britain’s streets, an energy revolution is quietly taking place

Perched on the side of a floating harbour inside a large, wood-clad shed, a gigantic heat pump – the biggest one in Britain – is drawing water from the river and using it to provide heating to surrounding buildings.

It was built by Bristol City Council but taken over recently by Swedish state energy giant Vattenfall, which is now expanding the system across the city. At the plant, a maximum of 153 litres per second is being abstracted from the river. On the day we visit, the water temperature is about eight degrees Celsius.

The heat pump then uses the water to warm a refrigerant chemical with a very low boiling point (in this case ammonia), which turns into gas and is then tightly compressed.

This in turn raises the temperature, with the gas then used to heat pipes that carry separate water in a circuit around the local district.

After the heat pump has worked its magic, the water originally abstracted is returned to the river about three to four degrees colder than before.

So long as the water temperature is around 7 degrees or more, the machine can achieve a “coefficient” of about three, says Lee. This means every kilowatt of electricity put into the heat pump generates about three kilowatts of heat energy in return.

65' temperature water is supplied as a preheat to be made use of.

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#139 2024-01-06 10:19:18

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

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#140 2024-01-14 09:33:01

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

I have seen some cheap ground sand videos that for heating and for cooling with or without heat pump use.
The heat loop collects it during the summer months when its hot dumping the cooling loops exchange into the thermal pit of sand.
Of course, the heating loop goes in reverse for winter.

The geothermal heat pump using ground sand with a loop of plastic pipe coiled in a trench of depth which is 3 to 8 ft that is from 24" to 4ft wide with a length of 100 ft with sand being about 2 ft for most homes and more for a larger one. The plastic pipe is 3/4" to 1 1/2" in size to get through put of fluid movement.

Cheap Geo Thermal Air Conditioning video

My DIY Geothermal System Was So CHEAP!!!

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#141 2024-01-14 10:59:24

tahanson43206
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Registered: 2018-04-27
Posts: 18,131

Re: Thermal Energy Storage

For SpaceNut .... Thanks for post #140 and the links you provided....

If you are willing to dive into those links a bit for us, and report back, it would be interesting ot know how many feet of hose were coupled together to hold the fluid for the transfer of thermal energy to and from the sand.

Does the kind of hose used make a difference?  What fluid is best for this application?

(th)

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#142 2024-01-15 17:12:52

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

Here is a cheap how to build Cheap Geothermal System

it uses a car radiator fan assembly to blow the heat in the loop
FSHHW1CG825D4CK.jpg?auto=webp&frame=1&fit=bounds&md=c3a67a282ff51e3a755c74b84beeb030

plastic tubing sizing diameter for flow rate and heat amount
FZYJP4RG825I9C3.jpg?auto=webp&frame=1&fit=bounds&md=02a718ac1cf110205d639cd25a30211e

4-Step Guide to Designing Geothermal Systems
Step 1: Heat Loss/Gain Calculations

Geothermal Property Requirements - What To Know

Homemade Sand Battery [DIY Climate Battery]


Passive solar heating wall
Build an Inexpensive Solar Heating System

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#143 2024-01-21 10:41:41

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

A different view on the term battery https://youtu.be/6N_DgelIIeQ?si=GPZtxBs7N89d_Yoi

Video on geothermal ac and heating

https://youtu.be/EAE-uguH0Ys?si=_459E6xBGnDUhLol

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#144 2024-01-23 08:29:46

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

Expert settles debate on keeping heating on all day or only switching on when needed

The Energy Saving Trust, on its website, suggests that it's best to heat your home when you need it and recommends the use of timers. They say, "Heating controls help you keep your home comfortably warm, without over-heating and wasting energy. By installing and using your heating controls effectively, you could save money on your heating bills and lower your carbon emissions."

However, some experts who spoke to MoneySavingExpert.com think some houses may benefit from a "slow and steady" method, depending on their heating system type. Heat Geek suggested that people with modern boilers or heat pumps, who spend lots of time at home, might find it more efficient to keep temperatures about 18 or 19C (64F to 66F).

However, keeping the heat on low all day isn't always the best option. It can cause heat to escape quickly from poorly insulated homes, leading to more expensive utility bills. Other specialists, however, attribute continuous low heating to condensation build-up within walls each time the heater is turned off, which can conduct heat outside eventually.

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#145 2024-01-26 04:03:42

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

New ceramic material for solar thermal energy storage.
https://www.nextbigfuture.com/2024/01/i … lants.html

This is a good technology to deploy in some of the southern US states and Mexico.  Like all renewable energy technologies, its performance is highly dependant on locality.  No good building something like this in Britain or Germany.  But Texas and New Mexico have the resource.

In the US and Mexico, this sort of technology can benefit greatly from economies of scale and an integrated life cycle.  Once we have enough solar thermal plants up and running, we can establish dedicated facilities for their recycling and maintenance.  This shouod help bring down costs.  The neat thing about this idea is that the bulk of components can be made from steel.  A material that is almost infinitely recyclable.  So solar thermal is sustainable in a way that PV just isn't.

Sustainability and cost effectiveness could be improved further by bringing energy consuming industries to the resource, rather than attempting to transmit the power.  Point focus solar collectors are capable of producing very high temperatures.  Heat at these temperatures has industrial applications, such as brick and cement manufacturing.  Aluminium production is a very electricity hungry industry.  If solar thermal is able to produce baseload power for a large fraction of the year, the aluminium smelter can be colocated with the solar plant, eliminating transmission costs.

Mexico may have a unique advantage in these sectors, because its northern cities represent population concentrations that are surrounded by desert.  The industries and solar plants can be built relatively close to these population centres, which have good transport links into the southern US.  It would be even better if railways could be extended to these places.  But the mountainous geography presents a challenge.

Last edited by Calliban (2024-01-26 04:33:55)


"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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#146 2024-01-26 05:36:48

Void
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Registered: 2011-12-29
Posts: 7,390

Re: Thermal Energy Storage

That sounds like it could work for the Moon also, perhaps.

What could one do in microgravity?

Done

Last edited by Void (2024-01-26 05:37:59)


Done.

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#147 2024-01-26 17:37:21

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,306

Re: Thermal Energy Storage

Concentrated Solar Thermal (CST) uses mirrors to concentrate sunlight, converting it to heat, which can then be stored or used to generate electricity.
Heated ceramic particles act like a battery, storing energy as heat, for up to 15 hours. Traditional CSTs are limited by the heat transfer fluids they use. Common fluids, like molten salt or high-temperature oil, can only handle up to 600°C and 400°C, respectively.

However, the ceramic particles the team is working with can endure temperatures over 1000°C.

The ‘falling’ part of this method uses gravity to heat these tiny, dark-hued ceramic particles. Each particle is less than half a millimetre in size. The particles are dropped from a hopper at the top of the tower, and heated as they pass through focused solar energy. In a shortfall, their temperature can shoot from 500°C to 800°C, and with more advanced setups, possibly over 1000°C.

10,000 mirrors to replace a 100MW

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#148 2024-01-28 16:38:25

Terraformer
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From: The Fortunate Isles
Registered: 2007-08-27
Posts: 3,857
Website

Re: Thermal Energy Storage

A lot of handwringing in Britain recently over the Port Talbot blast furnaces shutting down. But we were importing the ore and coal! I don't think we'd be less secure importing steel from say Australia, which has vast deserts it could use to power production.

Maybe parts of the world without access to reliable cheap power will just have to abandon heavy industry and refining and import energy intensive materials from countries that have big deserts. Some of which are fairly friendly, if remote. Since Britain has largely already abandoned it, it won't make much difference here.

Luna would have a signficant advantage over Terran deserts for solar thermal. Easy access to hot and cold. How hot would a black flat plate collector in direct sunlight in space get? How cold if shaded from it? Building out energy with indigenous materials might be done quite rapidly. Good for refining Aluminium, and shooting it home with railguns...


Use what is abundant and build to last

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#149 2024-01-29 16:52:17

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

Terraformer wrote:

A lot of handwringing in Britain recently over the Port Talbot blast furnaces shutting down. But we were importing the ore and coal! I don't think we'd be less secure importing steel from say Australia, which has vast deserts it could use to power production.

Maybe parts of the world without access to reliable cheap power will just have to abandon heavy industry and refining and import energy intensive materials from countries that have big deserts. Some of which are fairly friendly, if remote. Since Britain has largely already abandoned it, it won't make much difference here.

Luna would have a signficant advantage over Terran deserts for solar thermal. Easy access to hot and cold. How hot would a black flat plate collector in direct sunlight in space get? How cold if shaded from it? Building out energy with indigenous materials might be done quite rapidly. Good for refining Aluminium, and shooting it home with railguns...

UK politicians were stupid enough to allow the country's nuclear powerplant construction capabilities to die in the 1990s and early 2000s.  We are now paying a fortune trying to resurrect that capability.  The withered state of this country's industrial sector is making it harder, more costly and more time consuming than it wouod have been in previous decades.

The UK could import crude iron made elsewhere and convert it to higher grade steel using an arc or induction furnace.  Impurities can be removed using the basic oxygen process.  This is how the US makes steel.  They have very few blast furnaces left and they import pig iron made in places like Russia, India and China.  Basically, wherever they can get reduced iron for the lowest price.

Even without coal, hydrogen or natural gas could be used to make crude iron.  Grind up iron ore into small particles no more than 1mm in diameter.  Mix it with about 10% crude metallic iron powder.  Next, put the mixture into an induction furnace and heat it to 1000°C.  Inject hydrogen into the furnace.  The hydrogen will reduce iron(iii) oxide to metallic iron at the grain boundaries.  After several hours, switch off the induction furnace and let it cool.  Once cool, shovel out the material and mill it again.  Use an electromagnet to remove the crude iron powder from the crushed material.  Put half of the iron powder back into the induction furnace with a fresh load of iron ore.  Put the remainder into an arc furnace, burn off impurities with an oxygen lance and add charcoal powder to bring carbon content up to the right level.  Voila! Carbon steel.  This can be done entirely using electricity.  The problem is that the UK appears to be commited to a path of renewable buildout with natural gas backup, which is making electricity eyewateringly expensive.

Last edited by Calliban (2024-01-29 17:04:34)


"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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#150 2024-02-09 07:57:44

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,572

Re: Thermal Energy Storage

I am sitting in a cold house right now, because everyone else is out and the cost of heating my house with gas is extortionate.  My mind has wandered to the topic of heat batteries.  Could we use heat batteries to transport heat from warm equatorial places to cold northerly places?

My idea is a floating steel cylinder, 100m long and 20m wide.  Inside the cylinder, we have another steel tube 10m wide full of crushed rock.  The gap between the two is filled with insulation.  The steel cylinder floats in the sea, with roughly neutral bouyancy.  On the saharrah coast, we build a trough solar plant.  The thermal battery is pulled onto a slipway close to the plant and the rock is heated to 400°C by blowing hot air through it.  When fully charged, the heat battery is pushed back into the sea and coupled to other batteries by cable, like a string of sausages.  The whole string is then towed to the coastal cities of Northern Europe.  The batteries are decoupled, pulled onto slipways and plugged into city district heating networks.  Heat is extracted from the batteries by pumping water through the inner tube and harvesting the hot steam.

A single thermal battery, would contain 23,562 metric tonnes of quartz rock.  Taking specific heat of quartz to be 1KJ/Kg.K, the total heat stored by heating from 30 to 400°C, would be 2.42GWh.  That is enough heat to cover the winter heating needs of 34,600 UK homes for 1 day.  Following discharge, the battery would be towed back to the solar plant and recharged.  Any thoughts on the feasibility of this idea?

Taking the UK as an example.  The country has roughly 25 million homes.  Assuming we drain a thermal battery in exactly 1 day, in winter time we would need 723 of these batteries plugged in at any one time.  The distance from Machester to Marakech in Morroco is roughly 2500km.  I am going to take that as average transport distance.  I am going to assume that we tow the batteries through the water at 10 knots, which is 18.5km/h.  Average travel time would be 5.6 days in each direction.  Let us assume charging time is one day.  That works out at 11.2 days travelling, one day charging and one day discharging per cycle.  So we would need 9544 of these batteries to ensure that 723 of them are discharging at all times.

I am going to assume we can make these batteries out of low alloy steel tube, 1" thick.  That may be optimistic given diameter.  But as a starting assumption.  The battery is 20m wide and 100m long, with an inner tube that is 10m wide and 100m long.  For each battery, we would need 10,053m2 of 1" steel plate.  That is 1992 tonnes of steel.  So 9544 such batteries would require 19 million tonnes of steel, or 280kg per capita of UK population.  That is a lot, but is a lot less steel than we have in the UK vehicle fleet.  Of course, the batteries are not the only investment required for this system.  We also need solar heating plants in the saharrah and heat distribution networks on the UK side.  But this looks like it could be just about feasible.  It would be more achievable if we could make the batteries out of concrete.

Last edited by Calliban (2024-02-09 08:27:58)


"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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