Storing wind energy 1

[SomptingGuy]

http://www.globalnewenergynetwork.org/news.php?news_id=2190696

Can anyone shine more light on this?

It looks quite simple the way it's described: excess power created by the turbine is used to pump out the vessel against (big) hydrostatic pressure. Power is returned by reversing the process.

But what's left in the vessel as it's pumped out? A vacuum (which would boil off the remaining sea water), air from some breather pipe? Other?

- Steve

 

[cranky108]

Studies show that time of day rates don't have a big impact on residentual. Some business might.

 

[IRstuff]

"This is an example classic monetary feedback being used to optimize the distribution of resources, and the same model can be used for other means of equalizing demand vs generation."

I think people neglect just how much inertia there is, particularly for power bills. To wit, until my coworker's electricity bill hit $300, he hadn't done anything to curtail usage. But, even with that curtailed usage, which was driven by A/C, the usage time remains unchanged, since it's sort of moot to run the A/C in the wee hours, when the heat load is at its greatest 12 hrs earlier.

I think "monetary feedback" simply optimizes the distribution of money into the bank vaults of the power companies. The peak demand period is basically fixed to the couple of hours before noon to after 6pm, due to heat load driving A/C usage. And, unless forced to, companies are loathe to up the ambient temperatures because grumpy, hot, employees are more likely to crash profits than the cost of electricity.

TTFN
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[cranky108]

In some locations the peak is midnight to 6 am for Winter peaking utilities. And it is because of heating.

What I see is the weather, here, in the summer is typically mild, but with the advent of AC the usage is 24/7.
The issue is the conditioning systems tend to condition, rather then equilize the inside and outside. So maybe a different kind of system needs to be developed.

 

[IRstuff]

I think the whole point of an A/C is NOT to equalize, given that the comfort zone for people top out below 80F, but the outside temperature can easily be > 90F, even in relatively temperate regions. One common approach is evaporative coolers, but given that we're in a drought in the LA area, that's not going be particularly viable. Moreover, such coolers dump a truckload of moisture into the cooled air, and the higher humidity might be uncomfortable.

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[racookpe1978]

Mass, intrinsic (already moving) velocity of that mass or potential energy (pressure and temperature) of a static mass, efficiency of that mechanical-energy-by-converting-it-to-useful-continuous-torque, and ability to restore that original stored energy, right?

So, exactly what is the "stored energy" they are (1) going to release to convert to continuous torque?
(2) going to use off-peak available electric power to re-compress/restore to serve at the next cycle?

Pumped storage as at Niagara is near-ideal. A safe, very heavy stable liquid already delivered to the base of the suction of the safe, reliable, easily-controlled suction of the pumps at a continuous rate from a inexhaustible supply upriver that will be well above the minimum NPSH of the pumps. Immediately available, cheap, reliable hydro power from the plant just yards away to re-pump up the water to a stable stored elevation a few feet higher in the (very expensive! VERY controversial pond) above the pumped storage facility under near-unique conditions where that hydro power is NOT needed at night and so can be used to power the pumps to move the water, but the hydro flow IS available due to the Canadian-US early water conservation agreements.

Now, what fluid is being compressed at what efficiency of (original electric) power to stored energy many feet underground/underwater to vented energy (back at the surface) back to power?

If air, you have much less efficiency than with water pumps. Much lower final pressure unless you use positive-displacement compressor-style designs rather than fans - at great change in complexity! Now, if they assume that the compressed gas is "stored" underwater but pressurized by the height of the water column above the gas, then the continuous pressure relies on the collapsing "piston" of a tank with its bubble maintained by a flexible membrane or piston. If the underwater concrete tank is merely the pressure vessel for the stored HP gas, and the underwater location is merely a nearby storage location for holding the HP gas until vented back topside, then you can claim very little "pressure credit" for the outside water pressure holding the internal gasses at bay, since the inside air pressure varies. An externally-pressurized spherical concrete tank can resist external pressures, but they would need to balance the need for greater stored pressure against tremendously higher construction and installation and connection costs.



Now, I grant of course that the buoyancy problems can be solved by the simple application of "more concrete" on the base of the tank. Leakage could be solved and the ever-moving air pipeline from underwater to the topside power plant can be solved - as indeed it has been in the oil industry.

Nothing comes free except college-level "studies" by physicts who DON'T have to justify their assumptions and approximations to ANYBODY. Who are responsible for nothing to nobody for accuracy or reality except writing the application to get their next grant!

What has somewhat been successful is compressing air under ground in salt deposits, then re-venting that air into the burners of a combustion turbine topside to reduce the losses of using the CT compressor. Not a large savings, but enough to pay the design and construction costs.

But offshore? Just how much are they claiming the tanks will cost installed and hookeup?

 

[cranky108]

If size is a concern, then grid size may not be possible. Maybe you should aim for something smaller.

 

[davefitz]

Well, the daytime peak for A/C usage exactly coincides with PV output, so there should be provided more encouragement to install PV, maybe even require it in new homes .Other passive techniques to reduce solar insolation into the home should be applied as well ( solar screens on south and west windows).

The bigger issue is addressing the random nature of wind energy. We are reasonably sure that tomorrow's forecast is increasing brightness during the early mornging hours, followed by complete daylight, and later in the day less brightness followed by night.Complete darkness expected all night. Not as sure about tomorrow's wind speed.

"Whom the gods would destroy, they first make mad "

 

[waross]

Here's an idea for discussion. For southern and tropical climes;
Use a VFD to drive an A/C compressor. Use solar power to add energy to the DC bus.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[racookpe1978]

Well, the daytime peak for A/C usage exactly coincides with PV output, so there should be provided more encouragement to install PV, maybe even require it in new homes .Other passive techniques to reduce solar insolation into the home should be applied as well ( solar screens on south and west windows).

Going to disagree with you there.

PV solar power only matches demand in an idealized government study promoting solar power.

Actual electrical power demand peaks early in the morning as people wake up and start things, then drops off considerably between 9:00 and 2:00 to 3:00 oclock. Afternoon peak is 3:00 through about 7:30 to 8:00. A/C needs drop off after dark, but more lights are needed and home entertainment and the like also increases slightly.

Solar PV is only available from 9:00 AM to 3:00 pm local solar time. So, it begins to generate power just as demand actually lowers - forcing the conventional generators to be cut back even MORE than they would no-solar "assist" and causing even more cyclical strains and cracks in the metal. Then, as the afternoon real peak begins to increase at 4:00 and 5:00 in the afternoon, solar PV drops off to near-zero levels.

 

[cranky108]

Theres another problem with PV, in that many fire departments will not attempt to put out a fire on homes with PV because of the concern of being elecuted.
With this fact it is likely homes with PV will be rated in a higher fire risk catagory, and thus higher preminums (and lower home values).

Another issue is clouds should be increasing according to the thread on global warming, which will deminish the PV energy generated.

So PV is becoming nothing more than an expencive toy.

Some studies show that with increasing wind pentration there is increasing grid instability. This is also showing up in fault recovery voltage recordings. There will soon be a push to require wind producers to continue producing energy into lower and lower voltage dips to help stablize fault recovery voltages. This will likely be followed by requirments for non-static var support requirments like what is being required of other energy types.

So it might be better to look at regional or local solutions for storage, rather than grid sized storage solutions.

 

[davefitz]

Cranky108,

First responders cocerns are valid and resulted in changes to NEC 2014- see pars 690.12 and 690.13 for remote disconnect requirements

"Whom the gods would destroy, they first make mad "

 

[TomDOT]

racooke - The demand curve sometimes looks like that. Have a look at the predicted demand in Texas today for an example:

http://www.ercot.com/

- pretty good match to your description for a relatively cool day in Texas when there is little AC demand.

However, summer demand (when our biggest peaks happen) looks totally different, and is much closer to the PV production curve, though lagging somewhat. Peak demand warnings from 2-6PM (CDT, so 1-5 CST) are most common. Fortunately for demand matching, most of the good solar sites are far to the west and most of the demand is weighted east. This shifts us closer to PV output matching the demand curve. Obviously that means some potential transmission issues.

 

[racookpe1978]

Unfortunately, no other states straddle the time zones like TX does.

 

[TomDOT]

Other (lower 48) states are part of grids (Eastern Interconnect, Western Interconnect) considerably larger than Texas and can use the same effect by siting PV in good sites toward the West of the grid. Works better for the Eastern grid, as the population is also weighted East.

These other grids are considerably larger than the Texas grid and can actually leverage a larger effect.

Also, the absolute best solar sites in Texas (El Paso and Hudspeth counties) are actually part of the Western Interconnect. Located on the wrong edge for time-shaving, unfortunately.

 

[cranky108]

Good point. Put all the solar panels on the Eastern grid. However that's not where many of them are going. All that sand in the west looks so inviting.

 

[ornerynorsk]

http://news.msn.com/science-technology/scientists-discover-how-to-generate-solar-power-in-the-dark-1

Somewhat related . . . .

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[IRstuff]

This one probably more palatable for technicals:

http://arstechnica.com/science/2014/04/new-solar-thermal-fuel-has-energy-density-of-lead-batteries/

This article points out to me a couple of caveats:
> Lead acid batteries are not particularly energy dense, but net charging efficiency is probably higher
> There's a phrase "given UV" suggesting that the azobenzene only does its deal with UV light, which, coupled with its 14% efficiency, makes it less efficient than batteries, and with more moving parts

TTFN
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[cranky108]

EPRI had a number of articles some years ago about storing energy is salt ponds. The sun would heat the lower layer of the pond, and be insulated from the air by the upper layer (with the middle layed acting as a buffer). The energy could be extracted with an ammonia steam cycle plant. It seemed to be somewhat pie in the sky.

It wasen't a storage system per say, but more of a energy production facility that could store energy.

I doubt any of these facilities were ever built. However it is possible to use an ammonia cycle plant off any current power plant to increase efficency. But for the cost and risk, I don't see any being built.

 

[IRstuff]

Thermal energy is usually a poorer quality of energy than, say, electric, because extracting useful is more difficult, and usually very inefficient.

TTFN
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[ornerynorsk]

Anyone here well-read on Tesla? Perhaps the subject of another forum.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.