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beenthere

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Need less insulation to store the heat using water if your heating a home directly with it.

The molten salt is better if your making steam with it.

1 cu ft(7.49 gallons) of molten salt only has 74.19kJ of energy per °C.
1 cu ft(7.49 gallons) of water has 118.66 kJ of energy per °C.

Depending on composition of the molten salt. It solidifies at 282°F.

Bolvan8

FrodoOne

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What is advantage of heating up 100 gallons of water to ~100 degree above ambient vs heating up 10 gallons of some molten salt to a ~1000 degree above ambient. Why and how?
Actually, the disadvantage of heating a small mass to a high temperature differential versus heating a large mass to a relatively small temperature differential is the "speed of heat transfer"/insulation problem - especially in a domestic situation.
For example, in any OECD country it is probable that the flues on combustion heaters must be at least double wall (and, probably, triple wall) wherever they are accessible or pass through any combustible building material.

While the amount of energy transferred in your examples may be (virtually) the same, unless the transfer can be made slowly there is a danger of physical injury to the equipment involved, to the building concerned and, much more importantly, to persons who may come in contact with any such elevated temperatures.

Hydronic heating is an obvious example. The radiators used with this system operate at a temperature which will not injure human beings if they contact them directly but the area of the surfaces concerned together with the temperature differential is sufficient to warm the environment for the human beings.

Bolvan8

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Thank you Beenthere!
Less insulation? Made of what pyrolytic graphite, aerogel? One way or another it has to be somehow connected to heat collector to get it in and heat irradiator to give it away when requested. How well those exotics will do? How much energy goes into their synthesis and maintenance of designated functionality?
Under any equal condition of practical energy storage for home use water is far better than any other. That was, is, and always will be a fact of reality.

Bolvan8

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Great point Frodo One! Thank you.

Bolvan8

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Let me get back to MAIN question again:
Is it possible to "power home" without grid and what it would take?
Conditions:
1.Consumers - pretty couple basking in harmony with nature and everlasting love, may be a kid or two
2.Servants - R2D2, C3PO, Terminator, Wall E, Transformer, Roomba or other "advanced printers" adequately programmed to "run the house", grow food in green-house, maintain "energy module"
3.Typical consumption 10-40 kWh
4.Average location, exotics ( oil, radioactive metals, etc. ) not available, Sun and its basic derivatives only
5.Average climate : summer +10 to +30C, winter -20 to +10C
6.Average weather : 1-30 days sunny, 1-30 days cloudy, humidity 45-85%
7.Photosynthesis is okay, but exploitation of animals- unhealthy, even unethical

Bolvan8

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Let us take ten cities and solve it.
1. Anchorage ( Sub Arctic)
2. Seattle ( Continental-Oceanic )
3. London ( Golf stream )
4. Moscow ( Continental )
5. Melbourne (Continental -Oceanic )
6. Tokyo ( Oceanic )
7. Kansas city ( Continental )
8. Johannesburg ( Continental- Oceanic )
9. Paris (Continental - Golf stream )
10. Honolulu ( Equatorial )

FrodoOne

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Need less insulation to store the heat using water if your heating a home directly with it.

The molten salt is better if your making steam with it.

1 cu ft(7.49 gallons) of molten salt only has 74.19kJ of energy per °C.
1 cu ft(7.49 gallons) of water has 118.66 kJ of energy per °C.

Depending on composition of the molten salt. It solidifies at 282°F.
Confusing (is it not) to mix two systems of measurement.
The amount of heat energy required to raise the temperature of 1 kilogram (1 Litre) of water by one degree C (Celsius) is close to 4200 joules, which is 4.2 kilojoules.

I realize that we may have obtained the relativities from different sources, but I have ascertained from the above that 1 cubic foot of water (28.3168 Litres), has an energy storage capacity of about 119 kJ per degree C, which is almost the same as that which you posted.

As for molten salt, I have no further comment, except for the obvious dangers of using any such substance at such a high temperature in any domestic situation.

Bolvan8

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Agree! let us stick to Celsius and kilogramms

Bolvan8

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Just to add one more thing: average energy ( power? ) availability from Sun on sunny day ~1000 watt per square meter.
If to use simple "heat panels" we can heat-up 1000 kg of water say from 20C to 30C. And stored 1000 Joules.
If to use more complex collectors ( lens, fresnel lens, "tv dish" coated with mylar etc ) we can heat up 1 kg of "molten salt" from 20C to 1020C.
And stored 1000 Joules.
BUT TOTAL AMOUNT OF ENERGY WE HAVE COLLECTED and stored IS THE SAME!

P.S. I used numbers " out of the blue". I hope you get my point.

Bolvan8

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If to REALLY forget about fossil fuels ( which in turn is just an energy of the Sun stored by Nature during long period of time ) and FACE REALITY one will discover that:
1. Constructing energy storage, regardless of available technics used, for average home energy consumption for more than 10-15 days IS IMPRACTICAL.
2. Development of devices capable to convert available sources of energy into useful heat or electrical 24-7 ( thus reducing or even excluding completely need for storage ) IS THE ONLY WAY.

FrodoOne

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Let us take ten cities and solve it.
1. Anchorage ( Sub Arctic)
2. Seattle ( Continental-Oceanic )
3. London ( Golf stream )
4. Moscow ( Continental )
5. Melbourne (Continental -Oceanic )
6. Tokyo ( Oceanic )
7. Kansas city ( Continental )
8. Johannesburg ( Continental- Oceanic )
9. Paris (Continental - Golf stream )
10. Honolulu ( Equatorial )
One must wonder what you mean by all of that.
(It is the "Gulf Stream" - we are not playing Golf.

Just look at the cities concerned and then look up books such as "Guns, Germs and Steel" (https://www.amazon.com/Guns-Germs-Steel-Fates-Societies/dp/0393317552)

Before that, look up "Mainsprings of Civilization."(https://www.amazon.com/Mainsprings-Civilization-Ellsworth-Huntington/dp/B000GQYDDI)

I suggest that you obtain both of these books and enjoy some of the experience of those who came before you.
Beyond all of that, do you realize how desolate for thousands of years was human "progress", prior to what is now called the "Reformation" and the "Industrial Revolution"?

Just think about it. You may have been taught about how the Pahroes of Egypt governed for 5000 years or so but what was probably NOT told to you was that nothing happened to improve living conditions for the population during that period.
(Think about it. 5000 years of NOTHING changing.)

Where we are now, just a few hundred years after the Reformation (Meaning, get rid of stupid ideas) and the Industrial Revolution, we have another technological revolution.
Certain persons may wish to throw human progress back to pre-reformation ideas, for their own deluded ideologies. However, I believe that any such retrograde ideas should/must be resisted.

Sic transit gloria mundi.

I know that I AM being argumentative or discussive - depending upon your point of view

I do welcome any discussion but I do hope that any such discussion will not be abusive.

beenthere

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To be completely off grid, and store enough electric. About 35KW of PV panels(even on cloudy days they will produce some electric), and 48, 48 volt 2.2 KWH saltwater batteries. So you would have enough KWHs stored for 3 days of snow, at a 30KWH usage a day.

In reality, 30KWHs a day is a large draw for people living off grid.

Bolvan8

beenthere

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Just to add one more thing: average energy ( power? ) availability from Sun on sunny day ~1000 watt per square meter.
If to use simple "heat panels" we can heat-up 1000 kg of water say from 20C to 30C. And stored 1000 Joules.
If to use more complex collectors ( lens, fresnel lens, "tv dish" coated with mylar etc ) we can heat up 1 kg of "molten salt" from 20C to 1020C.
And stored 1000 Joules.
BUT TOTAL AMOUNT OF ENERGY WE HAVE COLLECTED and stored IS THE SAME!

P.S. I used numbers " out of the blue". I hope you get my point.
I hope you realize that 1000 Joules is only 0.2777778 watt hours/.9480BTUs of heat.

Bolvan8

Bolvan8

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Gentlemen! Every point you made greatly valued and correct! I wish I could put more "likes" to both. Philosophical and technological aspects of the problem are obvious. Nor Latin or English are my natives tongues and I giggle almost every other word for correct spell.
Yet, matter remains at hand.
1. Beenthere - okay, some are capable to survive on little. Accepted, - where the "little" will come from? Let us set 10kWh, and no oils. Moreover - 5kWh - where from?
2. Frodo one - yes Empires rise and fall, it is only question of time ( until robbery and slavery becomes impractical ) . Selection of "cities" was made at random only to emphases differences of solar energy availability plus planetary conditions and yet similar needs for energy overall. We can set any location you choose.

Bolvan8

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Thus - 10 +/- kwh, 36000000 Joules +/-. What do we do? ( no fossils ). Sun keeps shining at at 1000 +/- Watts at any moment for so called unit of time for so called 4 +/- standard hours. Shell we put this boat to sail seas? or zeppelin the air? Are we Vern's? Poe's or Asimov's? Or we are those who are able to see world for what it is?

beenthere

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1. Beenthere - okay, some are capable to survive on little. Accepted, - where the "little" will come from? Let us set 10kWh, and no oils. Moreover - 5kWh - where from?
Solar mostly, a windmill generator can also be added on many systems.

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