Power Storage

Pick up a brick and put it on the table, job done.
Here's another power storage device.

Del

Through out history, the most dangerous way anyone gathers power has been done by politicians. They use many different mechanisms in doing this that most engineers despise.

I see right through your question.

Plant a tree.

Well said nick name. I was just about to write so. Energy is storable. Not power.

Politics also do not store power. Like other means of power, it's always transitory... although some can benefit from it through generations... many times in the same family....

I gave you a GA for that, even though I believe the last statement should have a bit more detail:

"The bow is a very good example for energy storing capability but when loading it the input power is a lot less than the power delivered when the arrow leaves, since the time involved in pulling the bow is much longer than the time involved in releasing it. The amount of energy required to pull the bow will always be more than the energy delivered to the arrow during release, due to friction and other losses.

You are right that "energy" will be less at return but considering the ratio of the times for charging and discharging the "power" even considering losses will be greater.

Nick,

You have a good solid point that one stores energy and not power, for power is a time dependent quantity. But be very careful when making this type of semantic argument. For the the question does not ask "can power be stored as power?" So if one takes power, does something with it and then successfully releases that power (either amplified or attenuated) then the something in between is a form of storage. One should also demonstrate that no power comes out from the something without storage happening first. The argument that it's not stored as power so power cannot be stored is specious at best. The musical performance I'm listening to now by Bob James is stored on my computer. This music is stored. The key strokes from my fingers were stored in a myriad of different places as it traveled to the CR4 website and then ultimately to the video graphics card eventually of everyone who wishes to read this thread. My thoughts, words, and keystrokes were all stored for various periods of time in a variety of different media than how it was originally produced.

Power is just another one of the vast number of things that cannot be stored in it's original, native form. But it most certainly can be stored.

I'm sorry, but I think that Nick's answer is not arguable.

You can't take power and do something with it, power is just energy performing a job, so the only thing you can do to it, is measure it. I think you mean energy transformation, wich by the way, not always requires storage.

And no, your computer cannot store music in a strict sense, music is composed of notes, tones, harmonics etc. all this in the form of various frequency acoustic waves; but your computer, like many people, can only "understand" 10 types of information, so the codified data needs to to be processed to reproduce the music.

As per your thoughts and words (entirely another matter), even they require transformation and/or interpretation (what if couldn't read english?, they would mean nothing to me). A pure thought, transferd to my mind, would be immediatly undrstood, even without the use of a language.

Yahlasit

So the copyright violation claims by the RIAA against bit torrent copying are completely wrong since no music is stored on any computer. Good luck reversing that decision.

I don't need to; those claims are against bit torrent copying, as you clearly stated.

Yahlasit

Also how can you say that Nick's answer is not arguable? I've argued against it. Therefore it can be argued. QED

Then again, one can say anything on a blog.

Touche ! That's a good one.

But I still hope you are not like Sir Francis Bacon, who believes that power and knowledge are synonims (I looked it up in many dictionaries) .

In the same fashion, I don't believe that a painters pallete will "burst in a wide range of beatiful colors". Or that the new fabric softener contains "scent capsules that will explode at the slightest touch". IF SO, such devices should be considered a threat to our nation's security, and thus be prohibited, strongly prosecuted and summarily condemned.

Ok let's cut the philosophical twist and go back into the OP's question.

Yahlasit

Before someone catches me.

Synonyms.

Yahlasit

One can say that nothing is inarguable. But in common usage, when we say a point cannot be argued we mean that one cannot logically and successfully argue the point. One can argue that the earth does not orbit the sun and one can argue that there is no gravitational attraction between the two bodies, but these points are reasonably said to be "inarguable". You have not argued against Nick's answer in any realistic, meaningful, sense, but only in the semantic sense. You have not described any means for storing "power."

I'm surprised that people are jumping on this argument with both feet.

Ok so what my argument is, is what is the definition of the word "store"? Now Merrian Webster's New Collegiate Dictionary defines store as "1: FURNISH, SUPPLY; esp : to stock against a future time." Nothing in this definition states that the item being stored must be in the exact condition during storage, only that the item can be used at a later time. Now by demonstrating that one stores thoughts and music in a form other than how they had been originated, I demonstrated this use of the term instead of citing a definition. Since several other people very succinctly cited ways that power gets stored as potential energy and then released again as power, I saw no need to elaborate.

Since you insist I will complete my argument. Now one of the other posts pointed out that there need not be a conservation of power, only a conservation of energy. This is why the power stored into Del's bow was considerably smaller than the power released by the bow. For it is the energy that must be conserved. The low power slow draw of the string produced the same energy as the rapid high power release of power into the arrow.

"For it is the energy that must be conserved." I see that now you wander between both concepts. but never mind, lets leave it like that.

What I would like to hear (or better said, read) from you is how can you store power, citing Blink's question: What mechanism do you propose for storing the rate "one watt"?

Yahlasit

This is like spoon feeding a boorish brat.

I was going to go through the minute details of charging an ideal capacitor with an ideal voltage source. Disconnecting the capacitor from the voltage source and then discharging the capacitor with a known resistor. The power source is the voltage source. An ideal capacitor does not generate power or energy it only stores energy. The resistor will dissipate stored power at a reducing rate. If one places a voltage regulator between the capacitor and the load resistor the stored power can even be at a consistent rate for a limited amount of time. Better yet the capacitor could be charged through a fixed resistor by an ideal current source forcing a fixed input power to be constant between charges.

Now again, you have added a new assumption that one must store only one particular unit of power, specifically one watt. This is not the stated request and immaterial as to if power can be stored. I have all along claimed and it appears that you cannot grasp the concept that since the stored and then released energy gets released over a period of time it can only be released as power. Power that was stored. One can argue that all power is stored power. For even the power released by a star comes from the stored energy created when converting matter to energy.

Now that I've repeatedly explained my position with even a citation to the definition of the word "store", please at least explain your position that power cannot be stored.

Now again, you have added a new assumption that one must store only one particular unit of power, specifically one watt.

I suggested a watt, because it is common and simple. If you'd prefer one horsepower, that would be fine. One milliwatt would be OK. A capacitor cannot store one milliwatt, or ten milliwatts or one hundred milliwatts.

An ideal capacitor does not generate power or energy it only stores energy.

Perhaps you are getting it. The next sentence should read: "The resistor will dissipate stored energy at a reducing power," rather than "The resistor will dissipate stored power at a reducing rate."

No amount of creating your own definitions for common engineering terms makes your argument correct. Power is a rate.

With Dell's bow, we can say that the rate at which energy is stored is low. Therefore Dells power output when pulling on the string is low: he is transferring energy to the bow at a low rate, i.e., at low power. (If you Google "50 pounds x 2 feet / 2 seconds in watts", it gives you 67.79 watts.) He could pull back twice as fast (i.e., with twice the power) but the energy stored would be exactly the same. His power is not stored.

Are you arguing just to be argumentative, or do you really not understand this?

Ok, I'll hold my tongue this time.

As you've pointed out time cannot be stored and if I maybe permitted to extrapolate, time cannot be created. Power is energy transferred per unit time. If power cannot be stored for release when requested then it must be created when requested. Since time cannot be stored or created, then for power to be controlled energy must be created. Energy does not get created.

Now to repeat myself, power is not a conservative dimension. So one does not store one watt, dBm, horsepower, ton of refrigerant or calorie per second to get only that measured quantity of power out of a storage device. As my earlier cited dictionary definition of the word "store" states; storage does not mandate conservation, only use at a later time. I'm not creating my own definition for the transitive verb use of the word "store". If you prefer a few web based citings for this word try "store" or "store" or "store". None of these definitions state or imply conservation. So if one puts in power of any quantity for use as power later, one can validly state that one is storing power. Energy is a conservative dimension. When one stores a unit of energy (Joule, erg, kilowatt-hour, calorie, etc.) only that amount of energy (or less) can be used at a later time.

So to conclude that power cannot be stored because it does not meet the criteria of conservation seems to be correct. But storage need not be conservative. You have a specious argument.

You continue to focus on the word 'store'. That is not the problem! The problem is your use of the word 'power'.

"If power cannot be stored for release when requested then it must be created when requested." NO! If you have a tank of water (stored potential energy), and you open a valve near the bottom of the tank, then there is a flow which was not there previously. That flow can, over time, do work, like lifting something or spinning a turbine. So now you have power, where previously (before opening the valve) you had none. Was the power 'created'? NO! It is simply a consequence of making use of part of the energy previously stored when the tank was filled.

The tank of water is quite analogous to a capacitor; you can store charge in the capacitor at whatever rate is convenient (within reason), and then leave that charge there for relatively long times. When you flip a switch to start a flow of that charge to do some useful work, suddenly there is power where there previously was none. Was that power 'created'? NO! It is simply a consequence of making use of part of the energy previously stored when the tank capacitor was filled charged.

I believe we've reached a stalemate. You refuse to accept my use of English definitions and the citations I've used, or my discussion of conservative and non-conservative definitions. I've deliberately not created a link to any of the myriad of power storage systems commercially available but here's one now, power storage system. Power and energy are time linked physical properties. By transferring energy from one place to the other power also gets transferred.

I've yet to see anything but un-cited repetitions of this claim that power cannot be stored and yet energy can.

I keep citing the definition of the word "store" for the original question asked if power can be stored. It appears that we agree that power is energy transfer per unit time. I could cite a reference stating this, but I'm not sure you will accept it. So the dispute lies in the definition of store and storage. I will not repeat my cited definitions again.

Enough is enough.

"I believe we've reached a stalemate." Apparently so!

I have no problem with your definitions of 'store'. The problem is with the definition of 'power'. You, and power storage system, among many others, are using the colloquial definition of 'power', which has no mathematical basis whatsoever. Look up the definition of 'power' in any book (you choose) intended for use in calculations by engineers or scientists, and you will get something that boils down to work/time or energy/time. That is a rate, and no rate can be stored, in the sense of providing anything besides information at some future time.

I have 60 Watts stored in my brain, as the standard size of incandescent light bulb for home illumination. Having that information stored in my brain, or on paper, or in my computer, or on the internet, does not allow me to illuminate that bulb for even a tiny fraction of a second. Hopefully, over time that information will begin to fade and be replaced with something like 3 Watts, as the standard size of an LED lamp for home illumination. Even that much smaller power level can't be provided from information alone.

Let us ask a basic question is power= energy per unit time?

I think not.

It is not per unit time - it is time derivative f energy ie = dE/dt

and anything time derivative of a physical quantity can not be stored or can it be?

Velocity = time derivative of distance (or acceleration ?)

Check my post#42. Any rate can be determined either as an instantaneous value (eg. V=dx/dt) or as one or another form of average value (eg. V=∆x/∆t). Storing any of these rates stores nothing more than information.

Exactly.

In fact, the title of the power storage link, "Development of 16 kWh power storage system..." is nonsensical. 16 kWh is a measure of energy, not power.

In my line of work, the distinction between a battery's energy density and its power density is critical. A high power density battery (with the ability to operate at high power levels) is very useful in a hybrid vehicle, whereas a high energy density battery (with the ability to store a large amount of energy) makes more sense for a BEV (battery electric vehicle). Almost always, you must trade one factor for the other.

Understanding that these distinctions are not merely semantics, but based on the underlying physics is essential, I think, to working with technology.

I do not agree. Considering the examples you bring what you store are codes able to release a saved energy same way as the initial phenomenon was. It is NOT same energy but an other one and you did not save the power but the way the other energy has to be controlled.

What you store is the INTEGRAL of the used power thus ENERGY.

By the way, by storing energy (and not power), we could talk about mechanical ways (elastic, thermal, pressure, potential - agains gravity or an electric field), chemical ways (fuels, reduction of metals, batteries), electrical (capacitors, superconductors)...

I think you can. I use solar cells to charge batteries. P=EI. P is Power so if you can store Voltage and Current then you can store Power. Recharging a battery is restoring the voltage potential and thereby will allow for power in Ampere/hr discharge rate. A rechargeable battery "powers" a circuit. I have a feeling someone is going to think differently but if you have a dead battery and recharge it to store Power which is Voltage times Amps is that not Power?

You're right! Someone is going to disagree!

The battery does not store power, it stores energy. It is correct that P=EI, but unless you continue that EI for a finite time T, the battery will have stored nothing! (Energy)=PT=EIT. I put energy in parentheses to distinguish it from E(Electromotive force,or voltage), since I can't produce a script E for energy with this editor.

The power required to charge the battery may be much less than the power taken out of the battery, as long as the time involved in charging is appropriately longer than the time involved in discharging. Charging a car battery, then using it to start the car is a good example The charging power may be a few dozen to a few hundred Watts over many minutes, while the power required to start the engine will typically be a couple thousand to several thousand Watts over a few seconds. As always, the energy required to charge the battery will be greater than the energy required to run the starter.

You are right Maveric !! I think in a different way.

You can't store current, since it is the intensity of a flow of electrons; and for such a flow to exist, you need to close the circuit, thus discharging your batteries.

Yahlasit

If you change that word power to energy, then the answer is clearly yes. Literally thousands of teams all over the world are working to try to find more efficient ways of doing it.

I suspect you are really trying to ask about storing large quantities of electrical energy. There are several places in the world (the Hetch-Hetchy system in California is an early example) where water is pumped up to a high reservoir during times of low demand, and that water is allowed to flow through the same pumps, but now acting as turbines, to generate electric energy during times of high demand.

I understand that a large flywheel system was just installed in the North-Eastern US, to do essentially the same thing.

Hi, we can store energy, using thermal energy storage system. This system composed of gas compression or absorption chillers, steel cylindrical tanks, cooling system and auxiliry equipments, using Ammonia for gas compression system or Lithium bromide for Absorption system. System starts in the night during less power demand, to store either chilled water or ice, as per design parameters. This arrangement could be used as district cooling system to cool and air conditioned a several buildings and factories in certain large scale area utilizing the stored energy, during the day shift, without running the chillers. Also one of the major use of storage energy is the increase of power output (Electricity) of power generation plant (Gas Turbines), by placing cooling coil in the air inlet filter of Gas turbine. In power plant high demand during day shift, system starts, to utilze the stored energy, while chillers off. The chilled water transferred by pumps into the cooling coil to cool the entering air to Gas Turbine. More decrease in inlet air temperature, more increase in air density, more increse in the power output of the Gas Turbine and the plant accordingly. The increase in power, due to thermal energy storage is around 25 to 30% of the total net output of each Gas Turbine.

I hope this could be one of the answers.

mhadary

Your is definitively one of the answers .

Yahlasit

See an early discussion on the subject:

Most-Efficient-Way-to-Save-Energy

Power is a rate and cannot be stored.

MAINSPRINGS! Mainsprings could be utilized to store excess solar and wind energy (power). When the capacity of standard storage devices, like batteries, is reached, or the power surge is more than the storage system can receive, rather than braking the generator, or sending the excess into a grid, instead send it to a DC motor that is geared like a powerful winch, which winds some type of mainspring. Then, that stored mainspring energy could be released mechanically as needed, and geared-up to turn a generator that would charge battery banks or run lighting systems in periods of low wind or solar, or in emergency situations or as supplemental power. A working model could probably be devised out of old leaf springs, which is reminiscent of those crossbow limbs above.

I go along with the term energy storage. A very simple application is the flywheel. A quick starting "No-Break" emergency generator design will often utilize a flywheel to provide continuous rotation of an emergency generator until a diesel engine for example comes up to full speed and assumes the driver status maintaining the frequency within +/- .1Hz.

The flywheel is driven at synchronous speed by a motor and upon power loss a clutch disengages the motor from the flywheel allowing the flywheel's energy to drive a generator, starting the engine which when reaching operating speed, overrides the flywheel and drives the generator.

The "pumped storage hydroelectric reservoir" system mentioned was pioneered in Europe in the early 20th century and the Rocky River plant in New Milford, Ct. was one of the U.S's first storage reservoirs of potential "energy" to produce electric "power".

As many have rightly suggested ENERGY can be stored and POWER is the rate of energy required to perform a work like H.P etc.

It is unclear what sort of energy you are interested in storing.

The simple conversion is converting kinetic energy into potential energy and vice versa.

Few of such examples of energy storage are,

1]Pumped storage power plants where electrical energy is converted to mechanical , fluid energy upward and stored as potential hydro fluid energy.

2]Tightened spring energy released as mechanical energy to run watches.

3]Storage of electrical energy as chemical energy in Batteries.

4]Compressed gas / air pressure energy

5]Hydraulic pressure energy in lifts and hydraulic press etc.

Choice is about which form of energy storage to what form.

To recapitulate many of the responses here, you can indeed store energy in various ways, but this is not the same as storing power (energy/time). Rather than dwelling on this distinction, and arguing over semantics, let's just assume that the OP meant to store energy but accidentally used the wrong word.

Energy can be stored in batteries, capacitors, pressurized tanks, higher-elevation bodies of water, springs, lifted weights, flywheels, and maybe a few other means. In each case, you need to determine how much energy it takes to charge the battery or capacitor, pressurize the tank, pump the water uphill, compress the spring, raise the weight, rev up the flywheel, etc. And then determine how much energy you can get back. There will be losses in either direction, which will determine the efficiency of the chosen process.

Then you must also consider the cost of whatever equipment it takes to perform whichever process, including what size of components it takes to store what amount of energy. If we grant that the OP meant energy rather than power, the answer is yes, according to the seven mechanisms mentioned, and possibly some others.

Not power, but energy can be stored. For eg latest solar power systems store heat enegy in brine filled storage tanks, to be recovered as steam to drive steam turbine generator during the night.