huge, really huge and cheap storage

[john j]

Wonder if anyone can set my mind at ease and tell me that this is impossible;

The mission is to store heat (in form of heated water), from solar or other source. You will need a piece of land, 25.000+ sq metres. Depth before you reach groundwater 15+ metres.

The soil should ideally be able to absorb water. The water is "seeped" (not sure this is the correct word) into the ground, leaving the heat in the ground, principle known from "seeping" down grey water. A size of 30.000 cubic metres is necessary in order to overcome losses from no insulation of the storage. Heat is collected again by u-pipes, washed down in the store, by tubes buried in the store or by other means.

Water may be picked up from rain-water basins, processed grey water, sea-water or the like. Is this mad? Cheers, John, Denmark. Europe.

[wdyasq]

Just a short story of 'Geo-Thermal' glory.

Several years ago the mental giants of the 'Heating and Cooling' industry decided to shove their 'revolutionary and money saving' ideas on the unsuspecting in the Fort Worth/ Dallas area. New devotees of the process bragged on the savings ... for a couple of years. Then, the soils tests not done originally showed the soil was retaining the heat pumped there during the long 'cooling season' (about 8 months of the year) and now the 'cooling power usage' was far above their neighbors with the inferior air-cooled condensers. Quietly, the 'ground loop' cooling units were replaced with air-cooled units.

They are now pushing 'Geo-Thermal' again with deeper coils spaced over a larger area. The hype is not pushed as much as the multi-speed, dual compressor unit technology on the latest 'high-efficiency' units. It has also been a generation since the last 'fools' were fleeced. Americans tend to have short memories.

I have lived in areas having 'flowing ground water' one can actually see in hand-dug wells. I doubt any energy could be stored there. Those areas would be ideal for collecting or dissipating energy with a 'ground source heat-pump' (as not to miss-use the 'geo-thermal' misnomer).

Any 'ground storage method' for energy should be verified before large amounts of one's own funds are invested in them.

Ron

[spinningmagnets]

"Passive Annual Heat Storage" (PAHS) means storing heat in the ground during summer, then use it in winter. The designs I've seen so far seem pretty expensive for what I consider a small benefit.

If you dig down below ten feet, the average soil temps are around 55F, and this makes the ground a very large heat sink. Using "geothermal cooling" and "earth tubes" you will have a high initial installation cost, that reduces, but may not eliminate, home cooling costs, but for storing heat...its a struggle.

If you have winter air temps below 30F, the "German Passive House" configuration pulls outside air through earth tubes (55F) to warm it to ~50F, then by passing the incoming air through a heat exchanger, the incoming 50F air is partially warmed by the outgoing stale/moist 75F air. The resulting ~65F air only needs a small amount of energy to reach 75F.

Lots of great ideas over at "builditsolar.com". If you have exposure to winter sun, you can store hot air from simple collectors using drums of water and dry stacked masonry as a heat sponge. easily scalable to any size needed.

http://www.geocities.com/~dmdelaney/Solar-thermal-energy-for-housing.html

There is also a trickle down solar water collector that drains to an underground insulated pool to store heat.

http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/solarshed.htm

The numbers for these seem to easily beat PAHS.

[wdyasq]

"If you dig down below ten feet, the average soil temps are around 55F"

Soil temperature depends on average temperature of the area. Here in North Central Texas it is ~75F.

If you could pull some of those holes and send them, I could get real good money for 55F holes here.

Ron

[spinningmagnets]

I'm guessing that Denmark is about the same latitude as Canada, eh.

Funny you should mention the 55F hole pulling, I am currently seeking investors...

Tax season is upon us. "The government that robs Peter to pay Paul, can always depend on the support of Paul" -Mark Twain (plus, they will end up with a sore peter)

[john j]

Thank you for comments, would really make a difference if we could save that summer heat a few months......

[DamonHD]

Hi,

I calculated that 20,000l to 60,000l (ie 20t to 60t) of water in insulated tanks would do it for our house in London:

http://www.earth.org.uk/milk-tanker-thermal-store.html

But I'm sure that I'm still not clear about what you're trying to achieve.

Rgds

Damon

[john j]

Damon, I was hoping to show a way to save heat, for a village, a group of people or as a supplement for a traditional heating co. I like your idea about milktanks. But you will probably loose a lot of heat, because its close to impossible to insulate things for weeks, and even worse; months. I am unable to calculate things, but read what others say. Its in danish, Im afraid, but I can try and find some figures if you like.

Cheers, j

[john j]

Another possibility, that seems interesting: Google "Saline gradient heat storage" or "solar salt heat pond"

[DamonHD]

Hey, I didn't claim that my madcap scheme was viable!  B^>

But at least those tanks are insulated already, and you could surround them with a thick wall of impervious and insulating concrete I imagine as had been used in at least one German thermal store.

Anyway, just an idea.  I'm not in the slightest bit offended if you can't use it!

Rgds

Damon