Thermal Storage

Water has a high heat capacity (specific heat), which makes it useful for transferring and storing heat energy. However, seasonal (rather than daily) energy storage still requires a large amount of water, and the large volume must be insulated to keep the stored heat from dissipating into the surroundings. This is usually too expensive to be useful. You could inject warm water into a well, but some of the water would leak away into soil porosity, and over a long time much of the heat would also be conducted away.

There might be some possible but unusual situations that would enable decent heat storage for a while, but for the most part it is not practical or efficient on a long-term basis. As thing stand at the moment, pumped storage and batteries are the best medium-term storage methods, and there are some possible uses of flywheels or capacitors, but even these methods are best for only fairly short-term storage.

I don't claim any crystal ball for the future, but I wouldn't anticipate much improvement of this situation.

You are suggesting that this could be a cost effective solution? Or a theoretical possibility?

Swimming pools have been used as heat sinks for heat pumps (cooling the house, heating the pool). Before long the pool becomes too warm, however. Ideally, the too warm point would come at the end of the season, when you could extract heat to warm the house.

People have buried rocks underground (in a volume about the size of a basement for the house) and insulated the outside of this chamber. Hot air is pumped in to warm the rocks, and then the rocks are used for subsequent heating, often for many cold days without sunshine. A similar thing could be done with water, although I suspect that a water to air heat exchanger (and the use of rocks) might be more economical.

Warming the well and the ground around it might have a beneficial effect, if you live where it is cold much of the year. But you'd have to think hard about it, if your heat pump is used much for cooling (for which you want the ground cold).

As I ramble on here, I am probably restating what Tornado has stated... it is hard to make use of stored low grade heat on a long term basis. For supplying heat at night, however, the systems like rock storage or interior thermal mass (large concrete interior walls), etc, can work well.

• What can be done, and what can be done with feasibility are two different things.
• A great rule of thumb is to match production with demand so that you can achieve maximum efficiency, or put another way,
• don't store energy, only fuel.
• storing heat for long periods is very expensive versus producing it.
  

Oh for goodness sake - until someone invents the perfect insulator - or an infinitely zero loss chemical store - put it up a mountain - or above a hole and recover it via gravity.

Recover what? When "you put it up" you just spent some energy, and you won't get it back on the way down. Anybody who has built thermal storage knows of significant BTU relative losses, in addition to minor pumping losses. It still works, but don't kid yourself, you'll not get out what you put in. Anybody who denies this is not being very transparent, which is the basis for innovation and improvement. I see a close parallel in the WVO movement. Guess where the denied losses are? Labor! Just because you think something is neat, doesn't mean you get it for free.

Turbine generation seems effective...how does one get a home based turbine system that is cost effective or in neighbourhoods at least to minimize power transmission losses and maintenace of the thousands of km of wire strung across all contin=ents with step up and step down modulating transformers requireing replacement at regular intervals..Yes gravity feed of falling liquid through a turbine seems the best approach long term..This is in response to put it up a mountain or above a whole..:)

I haven't done any calcs on it, but here are my thoughts:

If it is for new building construction maybe a grid of metal pipes in the ground under the new building would heat the ground in the summer. This should reduce floor heat loss for awhile in the fall/winter. Not sure if the pipes would benefit from fins or not, or if so, what the size/spacing should be. Might be best if the perimeter of this heated section of earth was insulated so the heat did not go out horizontally so quickly. Also, a horizontal layer of insulation at grade level around the building perimeter would be needed. Doubt it would be real practical, but that's one idea.

Another idea would be if the heat was of high enough grade to produce electricity (doubt it) then you could power grow lights to grow plants (food), can them, and eat them in the winter. Of course, in the summer, you don't need grow lights to grow plants if you have land exposed to sunlight! This unit might generate the electricity you would need:

http://www.stirlingenergy.com/

Here's a link with info on Thermal Storage:

http://en.wikipedia.org/wiki/Seasonal_thermal_storage

One other idea:

If you can use the heat to separate out a gas or other chemical that can be stored and burned later, you might do that. For example you could use power from PV panels or a dish-type collector (www.stirlingenergy.com) to create hydrogen via electrolysis; and burn the hydrogen later. Don't blow yourself up.

Electrolysis: http://en.wikipedia.org/wiki/Electrolysis

There has been a new development on heat storage using wax(Parafin) and graphite.

Google "CCNY's Solar Pod Innovative Technology"

"It transfers solar heat via a system of copper pipes coiled within the thick-walled tank filled with a composite powder composed of graphite (like pencil lead) and a paraffin, or wax, that melts inside the tank. The material transfers heat well and can store it for days. "So what we have now is a very powerful thermal battery that can drive our cooling machine, or heating or whatever is needed," says Professor Gonzalez."

They mention at least 2 days heat storage in a small package and give the figure of 10 Kilowatts. The construction seems low - tech as well.