How to store energy? cost effectively..

What about pumping water into an elevated water tank?

that is one I have thought of as well.. certainly works on the simple and low cost end... perfect for many complete systems. but what size water tank do you get to before a flywheel becomes better or accumulator is better?

I love gravity--Lift a weight to run the flywheel and keep it at a constant speed--Calculate and average of the intermittent force.

When the is an economy of force--Drive the flywheel and lift the weight--When the force wanes, expend force from the lifted weight?????Debounce the intermittent force, maybe.

Bob c is posting a good suggestion, I think. it can be done at the lower cost at present.

In fact, some countries include our china are preparing for the project, that is take advantage of extra energy to lift water into a pond or reservior. then use this higher potential energy to drive generator to give out elelctric power or some thing like that.

flywheel is another good choice, in fact it s used in many field like ferry etc.

now we have to ask, how much the resdual energy do you have? if its smll, an accumulator is a good selection.

you can also use this machine energy gnerate electric and then send it inot line net.

and what energy are you getting now?

Hi JE,

The system of water towers was very often used in the UK 150 years ago, the water was pumped up into very high water towers in all the big industrial cities here!

One of the best known is Tower bridge in London, the water being pumped up the two towers was provided by the overload power of two massive steam engines designed to pump sewerage/water. When they wanted the bascules lifted/opened they opened a valve and the falling water powered two pistons that worked on the lifting gears.

Glasgow which was also an industrial city in Scotland used this system for 50 years to drive their lathes and milling machines plus their tramways.

So I would also sugest this system for storing eccess power!

Spencer.

The best solution will depend on the size of your setup.

If you for example have plenty of water available and a 500m escarpment in your backyard a reversible turbine would do the trick.

The lower efficiencies on smaller pumps should out rule the Tank fill option.

Have a look at the winding mechanism of a grandfather clock.

a 1000kg mass lifted 20m coupled to a auto alternator might just do some power. The beauty of a weight is that it can be stored for months without loosing any charge.

I little bit more info may help.

I'm always a little short on info.. but I like your numbers

The idea of storage and conversion are all coupled.

I see no problem in lifting a ton or more to a good height.

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This is merely a pet project to harness some currently available energy in a slightly/completely new way.

my field tests have shown that I can be sure to generate a lot of short, but very powerful compression strokes.

... with a relatively small unit, I expect I could lift a ton of weight a meter every couple/few minutes, and much much more.. very quickly in a scaled up version.

If I allow the weight to drop at the predetermined height, I could be cranking a flywheel as it decends... and lifting another weight as it goes up..

.. good idea about the grandfather clock.. nice visual.

How about compressed air?

Also consider the economics. How much is the energy worth? Return on investment is a BIG THING for investors. If you have Bill Gates or Warren Buffett type of resources, it dosn't matter much, for the rest of us, it is important.

For truely large scale, pumping water up-hill is easy and well understood. Batteries of various technologies should not be ignored. Even lead acid batteries are still being manufactured for large scale UPSes and are deep discharge capable. But they do require maintenance and have some hazards associated (acid can be nasty to deal with).

And... don't ignore thermal storage. Some interesting research is being done with solid carbon (on an industrial scale) but on a tighter budget, well-insulated water is a great way to store energy, at least for reasonably short periods.

Carbon is better if you want to convert directly back to electricity (because water has that annoying phase change at 100C - so you can't use it to boil water ). However if you consider that we use a lot of our electricity just to heat water - storing very hot water can be a great energy saving - and it is easy to heat living spaces with hot water radiators for a further overall saving.

This helps with the numbers mentioned by Servant74 above about whether the energy stored is worth the price of storing it. Stored heat is useful in a domestic setting right down to about 40C - the temperature of your shower - so you can get a lot of use out of the system and the saving is the energy you didn't buy to heat things up.

- hottest water (90C+) can be returned to a boiler to generate steam with small added energy

- as it cools it is still useful for space heating through radiators

- cooler water for showering / washing etc

- no batteries, no toxic chemicals, just good old high specific heat H2O.

By the way - have a look at http://www.dlsc.ca/ - a whole community that stores heat energy from the summer sun underground, then extracts it in winter. Beautiful!

Good luck - let us know how you proceed...

There are a couple of methods....I remember reading about a fella who was lifting a weight with a hydraulic jack. Very elegant. I personally like compressed air because, well, I live in Canada, where water freezes. Compressed air is also good for distribution, capacitiy is easy to add, economies of scale are in place, equipment is cheap and easy to get. I have seen air engines which are more and more effective and efficient being advertised. (coogle air powered motors...grin!)

This forum was looking for a a new idea though...how about...heat. Mechanical motion driving a "slush box", creating turbulence in a fluid filled tank. Hydraulic fluid would work fine. You could even use "used" hydraulic flluid. Or water, perhaps with some sort of antifreeze added. Very efficient, much more efficient than creating electricity. And the hot fluid can be pumped anywhere. A windmill (for instance) can heat a house that way with no intermittent steps and there is no speed critical rpms. It might be hard to store the heat for more than, say, a day or two, but insulation is cheap and does not wear out.

Admittedly it would be hard to return that heat to mechanical motion with any efficiency. But gentle heat is useful enough for melting snow off of sidewalks, drying grain, or running refrigeration systems or warming concrete slabs under homes. If you have a mechanical motion just going to waste, this would salvage some of it.

hello everyone,

after reading all these good answers, i went back and read the original posting again. one key thing there is that JE is most likely in Chicago. so, most of the ways suggested would not be practical in an urban environment. yes, he could heat a fluid and use it to great advantage in the winter to keep his shop or business warm. it does tend to get cold there in the winter. boiler fuels do cost a lot of money. dollar wise this might be better than the next best idea which would be the air pressure to run power tools. electricity to run tools is less expensive than boiler fuel (i would assume). so what are the needs of JE? heat or productive power or both?

It seems like the original issue was storage of excess energy for later use.

yes, it was, but i assume it also is in chicago. can't see any dams, or hydro units there. so it is really site specific energy storage. also, end use of energy is imprtant. otherwise it is just hypothetical conjecture.

so, i see that there options in how to store the energy and options of what do with it. they should match up.

i see this as an interesting posting. with many interesting solutions. do any of the possible solutions appeal to the originator? a little feedback please.

Another consideration, is where the stored energy will be used, and what is the source of the "variable intensity reciprocation"? If the energy source is a water wheel, turning an electric turbine, the pumping of water up hill would allow the same electric turbine to reuse the stored energy. But if you convert the energy into heat, you will now need a separate device to turn heat into electricity. It can be done, but is it practical?

A good solution will require good information.

Minimize the conversion needed. Each time you go from mechanical to electricity or heat and back you loose about half of the energy.

If your source and usage are mechanical, lift weights, use flywheels...

If you pump water, use positive displacement pumps with a gearbox to control the release of energy.

Car alternators are inefficients but cheap when bought used.

Do some calculations and you will quickly figure out that if it is complicated, it will not pay for itself and become a nightmare to maintain.

Keep it simple.

i agree "keep it simple"

mechanical to liquid heat to radiators is simple.

mechanical to electricity to baseboard heaters is simple.

mechanical to air compression to tool usage is simple.

it is the "and back" that is not simple or efficient.

100% correct. In every reversible process, there is always one direction that is easy while the other one is difficult.

This is why nature has only one major process to convert solar energy to a useful form (photo synthesis). Everything else (to very few exceptions) basically transforms and degrades the energy originally captured by plants and plankton.

The beauty of nature is that the wast from one creature is the food of another until everything is degraded to nutrient form that are re-pumped with energy by the plants. Isn't that beautiful...

If we can also devise various small waste energy recovery units to get some useful out of our wasted energy, we will be in a much better position.

Examples are:

1- Using the gray water from the shower or process to pre-heat the cold water to the heater.

2- Using the heat from the air conditioner to heat the water.

3- Use the shock absorbers found on many machines to compress air (used in the factory) instead of simply producing heat.

It has to be simple and with the least storage possible. Storage is very expensive.

I calculated that my 27000l swimming pool (12' x 24') has only a few hundred dollars of heat in it from 0C to 35C. Needs a lots of space to store energy. Phase transition to ice helps but causes other problems.

On the other hand, using the gray water from the shower to pre-heat the cold water to the heater works well if you don't pay too much for the exchanger. It is simple and does not need storage.

Basically heat is easy to produce and can usually be used to make hot water. Most industry and home use a lot of hot water.

No Kidding--And how about loading a hydraulic accumulator while braking a car to stop and using the stored hydraulic energy to assist it moving again? Or a bike for that matter.

"And how about loading a hydraulic accumulator while braking a car to stop and using the stored hydraulic energy to assist it moving again?"

Last I knew, hydraulic accumulators store energy by using hydraulic fluid to compress air or some other gas. So why bother with the fluid? Just used a compressed air pump/motor and forget the lossy hydraulics.

Nitrogen in most accumulators.--

I was picturing a hydrostatic drive and high pressure to assist--Say a heavy, electric car out of the hole of locked rotor current on take off.

Air, if you don't like lousy(?) hydraulics.

Or load a spring--

There is a source of wasted energy in stopping a car that could be recovered, by some means.

In ASDs if you push a motor it will generate power and load the DC bus and fault it on over volt--A DC brake can be added to burn off the excessive voltage through resistors, as heat, but that energy is lost--There are regenerative drives that can use that inertia to help the motor change directions and recovers that energy. There are some that are designed to help a motor to stop.

I would look at a type of energy source that is more efficient at overcoming locked rotor current. Maybe DC is?

Just a thought--CHEERS

hello Mr Gee,

good answer. you said it so much better than me.

Hello All!

Thanks for the numerous and thought provoking ideas.. While I am in Chicago, I don't do all of my experimenting in the city, and while energy is expensive, I'm not looking to tap a local power source.

I'm converting some already available energy in a manner that is quite simple.

I wish I could share a lot more, but I'm quite familiar with the patent process.

I don't really need to share much to move forward.

Aside from heating the water for hot water and radiator heat, I've conceptualized most of these ideas in different manners.

...I understand the cost.. the competition.. the regulation.. the maintenance.. the return.. the many things that keep people from moving forward.

As with ALL of my simple ideas.. there is still many reasons to investigate further.

my first prototype was off the shelf free parts and worked like a charm. (disassembled)

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The end purpose of this concept would be to provide mechanical to mechanical power for things as simple as desalination, but i think electrical power will be more directly usable and easy to produce.

In terms of the amount of storage needed.. not much.. just enough to smooth things out over the course of the day... or night

... I'll just have it lift water, compress air, and accumulator and turn a flywheel generator with each stroke.

This afternoon I was at the Hideout Block Party... great too

I suggest you look over the discussion in the thread, Storing Green Energy, http://cr4.globalspec.com/thread/26663#newcomments