Storing Wind Power In Cold Stores

Roland Piquepaille writes "According to Nature, a European-funded project has been launched to store electricity created from wind in refrigerated warehouses used to store food. As the production of wind energy is variable every day, it cannot easily be accommodated on the electrical grid. So the 'Night Wind' project wants to store wind energy produced at night in refrigerated warehouses and to release this energy during daytime peak hours. The first tests will be done in the Netherlands this year. And as the cold stores exist already, practically no extra cost should be incurred to store as much as 50,000 megawatt-hours of energy. Here are additional details and a picture illustrating this brilliant idea."

Comments

Roland Piquepaille

[suso]

Um, what the hell? This guy has a spot on ZDnet now? At least we know what he looks like.

Re:Roland Piquepaille

[solevita]

When the summary said there was a picture, I didn't expect to see a blogger! I thought there'd be a windmill or something.

Re:Roland Piquepaille

[Lord_Dweomer]

How come there is no editor response? Seriously, every Roland story there are TONS of +4 and +5 comments bashing him (rightfully so), often times at the top of the comments, and yet the editors remain suspiciously silent. It is a slap in the face as a reader to be ignored like this when so much of the community is up in arms over this guy. Why do the editors refuse to give any comment on him?

Has anybody been able to do a rough calculation of how much he makes when his stories show up? Also, has anybody tried to contact ZDNet about him to complain?

But back to the core of the matter, Taco, why do you ignore us when we are all up in arms over this? It is only serving to make the editors look guilty even when that may not be the case at all. Prove us wrong!

April yet?

[flyingfsck]

Man, time flies. Refrigerating electricity - hmm, wonder how long it will last till it spoils?

Re:April yet?

[smartdreamer]

Maybe you are joking, but this as nothing to do with refrigerating electricity. It's about utilizing wind power to refrigirate during the night to be able to stop refrigirating during the day. Why? Because during the night, wind power over produce so it would be wasted! This is a simple idea but that can make a difference.

It reminds me about nuclear powerplants coupled with hydroelectricity. Nuclear power gives a constant output, but cannot be stopped shortly. So when they are overproducing, they pump water up transforming wasted energy in potential energy.

Re:April yet?

[Anonymous Coward]

I want to know how we can harness the power created by the vast vacuum between people that grasp sarcasm and you.

Re:April yet?

[OldManAndTheC]

the power created by the vast vacuum between people that grasp sarcasm and you.

Note: the technical term for this controversial concept is zero-comphrension-of-the-point energy.

Re:April yet?

[cbacba]

Love it,

There seem to be many April magazine Articles that float around for years. My all time favorite is the one about 10^40 bits in a crystal or maybe it was 10^60 bits. It was enticing people into april 1 mode for years after that - spawned a number of subsequent professional articles too. All you need for a crystal is something somewhat larger than the earth - and some interface circuitry. Those who shoulda known better tended to be those who were the last to know.

This may not be quite so similar but it's definitely no new idea to store energy from production time to usage time. I guess with higher temp superconductors, maybe a nice refridgerator might be in order.

The big problem this stuff tries to address is based on the factor that peak electric loading occurs mid-day - when it's hot out, most everyone is awake and working. It is a serious problem and peak demand electricity has been a serious cost factor. Solar panels do offer peak output mid day so can help by selling some of their rather expensive electrons at primo prices. Wind often is strongest with the coastal breezes in mornings and evenings - due to unequal heating rates of water versus land.

Unfortunately, for every conversion of energy - there are thermodynamic penalties that must be paid and cannot be overcome using whatever particular technique happens to be employed in that particular circumstance. The notion of using energy in heat (or lack there of for cold) is particularly bad in cases where the resulting energy needs are in other forms - such as needing electricity again. Thermodynamic efficiencies for heat engines are a factor of the difference in temperatures between heat source and sink - and the lower the differences - the less efficient it can be.

Something as simple as cooling down commercial refridgerators at off peak hours is probably a good idea both from energy savings standpoint and from cost standpoints - assuming the insulation is sufficiently good to keep out the heat and permit a net savings. As for new innovatinve ideas it hardly seems to be something worthy of more than a passing mention in some grocery store checkout line magazine article about 10 ways to reduce your corporate electric bill.

In some areas of the country, there are systems with devices tied to electric meters that offer another, slightly more intrusive alternative which is essentially to have the equivalent of an old pre text message vintage pocket pager wired to a power relay. When the little pocket pager radio device is activated, the relay shuts off the power to the customer device for about 15 minutes. Typically, it's big ticket items for consumers like electric waterheaters, airconditioners and irrigation pumps (for farmers). This is called load shedding and it's used to minimize some of that expensive daytime peak power. One can create a rolling temporary shutdown that can shed a few million killowatts continually. Often these systems are involved with tens of thousands of customers and cover areas that could be whole states.

Like the refridgerator at night thing, it doesn't tend to save energy, but rather to distribute it around to reduce the peak load - sometimes at the expense of actually increasing the overall usage.

Re:April yet?

[smartdreamer]

Memo to myself:
- Do not reply to a post trying to be funny with an informative answer.
- Go back to this post on April's first and have a good laugh.

Holy Frozen Kippers

[The Dobber]

This has nothing to do with storing power, it's simply a transfer of usage from on-peak to off-peak.

Wow.

Re:Holy Frozen Kippers

[peterofoz]

I might have taken physics a long time ago, but we learned that you make things colder by removing energy. So there can be no such thing as cold energy storage. You can consider a cold store to be like a vacuum storage tank as it creates a difference in energy which like electricity creates potential to cause energy in the form of heat to flow. It does make sense, however, to offset energy consumption from peak hours by this method. I'd seen a design discussed in the late 70's at Orange Coast College (Calif) for chilling a cold-brine in storage tanks below office buildings, then cycling the air condiditon pipes and transferring heat from the building and warming the cold brine. They had put the whole campus on a energy management system, driven by the mainframe, and all written in APL.

Re:Holy Frozen Kippers

[Anonymous Coward]

I know Idaho Power has been doing this for at least a couple of years. They pay farmers to turn their irrigation wells off during peak periods. This is just a way to reduce demand during heavy usage.

http://www.idahopower.com/energycenter/energyeffic iency/Irrigation/irrigationPeakRewards.htm

Re:Holy Frozen Kippers

[alshithead]

"This has nothing to do with storing power, it's simply a transfer of usage from on-peak to off-peak.

Wow."

You are 100% correct. It is not storing power. It IS more effectively utilizing generated power. Maybe it's not a big "wow" to you, but to me it's a fantastic (not so) common sense solution to better utilizing limited resources. The more we can utilize our resources as efficiently as possible, the less we need to generate/use/procure.

Re:Holy Frozen Kippers

[caseih]

Well electricity is not about energy storage per se so much as it is about potential difference. With mere physics alone we can show that by cooling off something to many degrees below the ambient temperature (and if we could keep it there at no cost), then we can extract energy out again (out of the ambient air) because there is a difference in temperature. Thus you can extract electricity out of the freezer from a certain point of view. Energy flows usefully in either direction. This is related to the entire field of geothermal energy production, which works in the winter so long as you have a heat sump (the earth). Of course none of this might have much to do with the original article. It's hard to know as Roland's blog adverts are often short on real details and facts. And being slashdot I can't possibly read the original article.

Re:Holy Frozen Kippers

[CnlPepper]

Yep. Wow. Yawn. Those Europeans are so damn smart........NOT! Before you go getting all jingoistic, the technology was first demonstrated by said damn smart Europeans in the 1890s. Have a read of Wikipedia's Pumped Storage Hydroelectricity page. There are plenty of examples of this technology other than the one you describe. One such example is the Dinorwig Pumped Hydro. Power station in the UK. The technology is already in widespread use.

Re:Holy Frozen Kippers

[VagaStorm]

D that and you will soon discover yor baterys aint working to well til you heet em up a bit :p

Re:Holy Frozen Kippers

[thc69]

heat is the most useless form of energy.

Tell that to this guy.

"night wind"

[macadamia_harold]

So the 'Night Wind' project wants to store wind energy produced at night in refrigerated warehouses

So do they release this "Night Wind" with a "Dutch Oven"?

This can be used in many places

[Reverse Gear]

I think the post is a bit misleading, energy is not stored by cooling down something, actually energy is taken away, but never mind.

As far as I can figure what is being done is to cool down these refrigeration rooms more when there is more power beeing produced because of the strong wind and then you don't have to run the refrigeration systems when there is little wind for a time as they slowly heat until some level.

I would think that even more power could be saved if the energy was used to freeze water and the ice then was taken to melt in the a frame used as insulation for the freezing houses.

I don't see this as much of a new idea though, it is something that has been talked about a lot here in Denmark, there are many other places where the use of energy can be spared when there is lot's of production from windmills, for example local heating plants, smaller refrigerators in homes (would require some kind of online connection to tell them when there is cheap electricity, but I think these intelligent freezers already exist), electric cars, pretty much anything with an attached battery really.

This can to a large degree be controlled by letting the prices vary on the market and let the consumer feel these variances also, that way it pays of to use energy when there is plenty of it.

Using the power when it is produced sure is more efficient than using the extra energy to produce hydrogen, but still that is still something that I think should be still done. The two things doesn't oppose each other as such, if we are to bring down our CO2 release we sure need a lot of windmills.

Re:This can be used in many places

[Rich0]

Actually, you don't need anything quite as elaborate as what this article seems to describe. All you need is the ability for power companies to charge rates that vary in realtime based on supply/demand, and to allow customer to elect to use these rates instead of averaged-out ones.

I'm sure a lot of industrial processes work on the principle that they need to generate x quantity of some particular good in a 24 hour period, but the capacity in the plant is such that they can maybe run at less than full output for some of the day, and catch up at other times. The refrigeration in this article is just one example of this sort of thing.

If the rates varied in realtime you could design your industrial process to automatically tailor its power consumpation to the going rate. As a result you can save megabucks on your utility bill, and the utility in turn can save even more bucks on now-unneeded coal-fired plants.

The same would apply in residential situations - people could have their air conditioners fluctuate their setpoint based on the price of electricity within some limit. If during a particular hour of the day power is cheaper than average go ahead and drop the temperature an extra degree or two, and then coast through times of price-spiking. Instead of brining plants online and offline utilities would just vary the price of electricity throughout the day. If the fluctuations in price are large enough homeowners would probably buy solar-based systems or energy-storage systems of some kind (bigger water heaters that don't run during the day, storage tanks to hold cold water for cooling during the day, etc.).

Basically all you need is an electric meter with online access to the power company, and a way for power-consuming devices to find out the current rate. For cheaper devices a simple timer would at least cover general on/off-peak times.

Anything that encourages energy-users to be conscious of the realities of electrical supply/demand fluctuation will only help the environment, the supply of fuel, the general economy, etc. With the current system a kWh is a kWh and consumers have no incentive to shift their usage off-peak.

Re:This can be used in many places

[Anonymous Coward]

I'm not sure how things are in America right now, but in Australia, they're rolling out a scheme called 'Time of Use'. Meters are automatically read every 30 minutes, or every 15 for large usage sites, and you're charged based upon the time that you use the energy. Currently it's split into 3 blocks.. Peak (business times) shoulder (evenings) and off-peak (nights, weekends) and differing rates are set for each period.

Energy Australia charge 22c/kwh for Peak, 8c/kwh for Shoulder and 4c/kwh for Off-peak.

Not as elaborate as your suggestion, but far more suitable for the average home user. It would probably benefit such 'cold stores' too, because I wouldn't imagine it would make much difference whether they're -20 or -40, so they could cool right down during the night, then use less energy during 'peak' hours. I would guess future developments might see small sites charging batteries during the night to power appliances through the day.

Re:This can be used in many places

[Rich0]

Adding user-feedback to a moderately unstable system like the electricity grid is not necessarily the best thing to do. Adding load-leveling capacity by storing power in the form of ice is a very, very good idea.

But in this case the load-leveling is being done by end-users. They just happen to be cooperating with the power company.

How would user-feedback make the system more unstable? Do you think that some users would set up their processes to INCREASE consumption when the price RISES? Users would either ignore the realtime rate, or they'd use it in a way that furthers the grid's goals - reducing usage when capacity is low, and raising it when capacity is high.

Right now utilities already do this in the form of on/off-peak metering. Generally only large industrial consumers are eligible (this varies greatly by country/region/etc). This is useful to save on gas-fired turbines and such, but as you point out wind is far less predictable - it might be more available at 1PM and less available at 1AM. To handle a grid with a lot of wind capacity you'd need realtime rates, and users who base their consumption on the realtime rates.

Regardless of the scheme you pick you need to make sure customers have incentive to cooperate. If you just tell them they're doing it for the common good they'll realize that they're going through a lot of trouble and possibly undertaking costs just to line utility executive pockets. If on the other hand you vary the rates in realtime, or give them breaks on their bills for participating they'll go along with it. Too often environmental initiatives are not reward-based, and as a result everybody pays them lip-service but silently undermines them. In most industries the greening-up of processes has not been the result of any desire to help out the environment, but rather large efficiency gains associated with recycling waste streams and reducing waste in general.

Why would he want to kill her in public?

[Dachannien]

store electricity created from wind in refrigerated warehouses

No, no, no.... There's no wind in these refrigerated warehouses. The point is that wind power fluctuates, so to smooth things out, this guy wants to use the electricity generated from wind power to overcool refrigerated warehouses at night, and then undercool them during the day when electricity demand peaks to make more of the electricity generated during the day available for other purposes.

Re:How to get rid of Roland Piquepaille...

[LiquidCoooled]

It can't work that well.
Afterall, you are posting in one of his articles.

alt fuels and systems

[drDugan]

Very nice. However, we're still just window dressing the Titanic.

500,000 years+ worth of stored energy in oil has been used in 200 years, and will be gone in another 200. Bummer. We found it, and used it. We have 6 billion people now (and growing fast) who want energy -- lots and lots of it.

All the alternative-fuels scenarios - even in the very best case where we grow vast oceans and fields of seaweed and switchgrass and use yeasts to process cellulosic 5-carbon sugars and make ethanol -- even in these best case scenarios (which incidentally would close the carbon loop), humans are still 1-2 orders of magnitude lower in energy production compared to the current oil-fueled system. If we add to that calculation efficiency measures we get closer, lower population - closer still, conservation - still closer... but: the harsh inescapable reality humanity faces in the next 30-50 years is this: there will just not be enough energy for the growing (first-world) population.

http://en.wikipedia.org/wiki/Cellulosic_ethanol
http://bioconversion.blogspot.com/2006/08/celunols -wet-biomass-conversion.html

We need to perfect nuclear power engineering, software, and extremely long term storage processes as soon as possible.

Re:alt fuels and systems

[Grail]

That, or we need to wean ourselves off the high-energy-consumption habit.

Oookaaay

[iminplaya]

Let me get this straight. The refrigerator is "feeding" the grid because it consunes less from the grid? Because we get some power from a wind turbine, right? Is there some kind of net metering thing going on here? Or is it just simple reduction of usage? Sounds like somebody's playing with words.

Article and post misleading

[AaronW]

I think both the article and post are misleading. Basically all they are doing is turning down the temperature at night and letting it warm up during the day. This just means that most of their energy consumption occurs at night, when there is often a surplus of electricity. It's a great idea though. Many forms of power generation cannot quickly adjust their outputs due to the wear and tear it would cause by temperature changes. I.e. coal, natural gas and nuclear power plants usually run at one output level, resulting in a lot of extra energy available at night when demand is low.

This wouldn't be restricted to just wind power like the article says. It would also be very useful for many other power sources.

One other method I heard about many years ago was to use the extra energy at night to pump water to a high elevation resavoir and during the day use that water to help generate electricity.

Re:Potential Energy of Water

[Dahan]

I've always wondered about using the potential energy of water (that is, raising it to a higher height), to store that energy to smooth out production versus demand issues for electricity.
Does anyone know if this is being done? It seems like it would be more straight forward than the refrigeration method mentioend in the article.
Have you considered Reading TFA? (Yeah, I must be new here):

... As a result many renewable-power plants have to store their energy, by raising water to a height or making hydrogen, for example, so they can 'save it for a rainy day'.

Well, an old idea in new disguise ;-)

[The Terminator]

Well, this usage pattern resembles much the old idea of a pumped storage power plant (Pumpspeicherkraftwerk), a hydroelectric powerplant where the water, which is used in high load times to produce electric power, gets pumped back uphill to a reservoir by use of the excess power of the basic load power plants like coal or nuclear driven ones.
This is done for decades now in the european grid. I had the opportunity in the late sixties to visit such a power plant at Schruns/Tschagguns in Vorarlberg in Western Austria.
It's a very impressive installation with a entire delivery height of more than 2000m (6000ft) in two stages. In the exhibition is also an impressive display of the entire european powergrid.

CU

Pumped storage hydro is common world wide.

[HornWumpus]

It really does a number on the fish though.

Re:Potential Energy of Water

[gtdawg]

Yes, it is being done in northern L.A. county.

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

http://www.osti.gov/energycitations/product.biblio .jsp?osti_id=7092283

Pumped Storage and Compressed Air Storage

[rohar]

This idea isn't really storage, it is just lowering usage during peak hours and making up for it in off hours. The idea doesn't seem to align with the mentioned wind power generation. I would think that except for during storms there is less wind at night at most locations, and they are talking about increasing load at night.

Other grid energy storage

Pumped storage could be adapted to wind.
Compressed air storage is another idea. The gas turbine generators have clutches in the compressor section and stored compressed air that is compressed in off-peak hours is used rather than the turbine powered compressor. The existing systems use the gas turbines in off-peak hours to compress air, but I would think that using wind powered compressors in a compressed air storage gas turbine plant would be a simple retrofit.

Roland the Plogger, wrong as usual. Real facts:

[Animats]

It's Roland the Plogger, wrong as usual, spamming to promote his blog. The Slashdot editors gave him two links this time, one without a "nofollow". Ka-ching!

OK, now the real info. Thermal energy storage has been around for years. There are thousands of installations. It's used when there's a big difference between day and night power rates. During the night, water is chilled, or ice frozen; during the day, the cold water is used for air conditioning. See Thermal Energy Storage Strategies for Commercial HVAC Systems for details on how to configure such a system. Also see CALMAC, which makes such gear. It was a spinoff from their ice-rink equipment business.

How many Can do this?

[JamesTRexx]

I think the question is also how many stores Can do this?
I work in the IT section for the biggest refrigeration company in the Netherlands, and from what I've seen every type of food has an specific storage temperature. Apparently a 2 degrees Celcius difference will make a big difference in the quality of food.

Making green energy from nuclear energy

[Portal1]

This is done a lot in Norway,

There they have double water dams/basins one high one low.
During peak hour the water is rushed down for electricity.
During night they buy cheap French nuclear energy to pump water back.

We called this making green energy from nuclear energy
(btw i am not against this scenario, but the energy is not really green )
Also a lot of energy is lost in the transportation from France to Norway

Better solution, combine it with windmills on the mountain ridges

Expert reaction

[Portal1]

Hi I am running a company that implements a lot of software for most of the dutch electricity company's

There is a special communication protocol used to communicate between these electricity company's
It is called EDINE and is based on EDIEL which is again based on EDIFACT
One of these messages QUOTE-RRV is specifically used to trade over and under production.
But is also used to trade possibility to not consume for a certain time.
Which effectively lowers the demand for a period of scarcity

This is used a lot in aluminum factory's that can effectively shut down for a day when there is a problem in a power plant
Of course if the same can be done for cold stores that is great.

Most of those company's are very wanted by electricity company's and they normally have very lucrative contracts
almost getting there electricity for free.

Hydrogen plants would be also very good candidates

Greets John

Re:Stupid idea

[hcdejong]

RTFA. They're not storing energy as heat and then attempting to recover it, they're modulating the energy usage of the cold store to buffer the grid. Cool down the store to -25 C during peak supply hours (which often don't coincide with peak demand), and you can switch off the refrigerator and let the temperature rise to -23 C during off-peak supply hours. This is beneficial regardless of whether the grid is powered by wind, solar or fossil fuel plants; wind power is just the sales pitch.

Re:Stupid idea

[toQDuj]

Actually, your idea to produce hydrogen at the windmills is one of the stupidest ideas in a long time. I was reminded of this by the CEO of NUON, a dutch energy company.

The argumentation goes as such: imagine clean power from windmills. Then imagine an electrolysis machine to produce hydrogen. then imagine a huge compressor, required to liquefy the hydrogen gas. then imagine storage tanks, which will slowly leak hydrogen. These tanks have to be regularly replaced because hydrogen tends to mess up the metal lattice structure, degrading the stability.

Then imagine actually transporting the remainder of the hydrogen across roads (pipelines would lose too much hydrogen), and subsequently converting what's left into electricity.

For your idea to work, we need hydrogen storage materials, which can be loaded and unloaded under more gentile conditions. Look towards metal hydrides for a potential answer there.

B., M. Sc.

p.s. RTFA. please, before you start labeling people as stupid.

Cold.....

[IHC Navistar]

You can't store "cold". The concept of 'cold' is just a simpler way to describe a thermal vaccuum - or a 'heat vaccuum. O Kelvin is just the thermal equivalent of a perfect vaccuum. The quantity of heat energy in a given space is what determines how cold-or hot- something is. Heat is the measured energy, and 'cold' is simply the absense of heat. Therefore, you cannot store the absense of something.

Wheather something feels cold or hot to us is measured by how hot or cold it feels. But, regardless of how cold it feels, there is still heat present-evein in ice or frozen ammonia. Heat content only reaches zero at 0 degrees Kelvin.

I'm not a physicist, but I think of the concept of 'cold' or 'coldness' by defining 'cold' as a "Thermal Vaccuum".

Re:This doesn't matter with regard to wind power.

[jonbryce]

Yes, they can do this without using wind power, and they probably do. That isn't the point though.

The point is that the output of a wind generator is pretty erratic and unpredictable, and this limits the % of total electricity that this source can supply.

If you have a power input that can take an erratic and unpredictable electricity supply and still function effectively, then this increases the % of electricity that can be supplied by wind turbines.

Re:Potential Energy of Water

[mccdyl001]

This has been implemented near Cape Town in South Africa. During the evenings, hen demand for electricity is low, they pump water from a resevoir on the cape flats (i.e. nearly at sea level)(google maps link) up to the top of a nearby mountain (link to it on google maps. Then during the day, when the electricity is needed, they let the water flow back down and power a turbine generating surplus for the grid. I think this was implemented since pretty much all of cape town's electricity is supplied by Koeberg nuclear power station (when the turbines aren't breaking down), and from what i can gather, the electrical output from a nuclear plant is pretty constant and would otherwise be wasted if there was not some way to temporarily store it during quiet times for use in peak times.

Actually, I was once speaking to a farmer who owns the farm that the upper resevoir is located next to, and he pointed out a large many-story high concrete pillar (you can see it in the google maps link to the upper resevoir i inserted earlier in this post, to the lower right hand corner of the dam). He reckons, and i have no reason to doubt him, that its there to absorb the backward wave of water that is created when the downward flow is shut off each night. The way he explained it was its almost like a super large tidal bore flows back up the pipeline that was drilled through the mountain to the lower reservoir. Supposedly it would spout a column of water about 50 meters into the air otherwise. Anyway,thats totally irrelevant to the article, just thought it would make the links a bit more interesting.

Re:This doesn't matter with regard to wind power.

[maxume]

Except that there might be wind power available in the middle of the night that is currently getting pissed away into the ether. There isn't really any other power source that happens to have excess capacity available in the middle of the night; wind is generally built as 'peak' capacity, because it might not be there once in a while. This system highlights a way of making sure that the energy gets used when it is available(it is good for the power company to simply 'give' the power to the cold houses, as it reduces daytime demand in a predictable fashion).

Re:Stupid idea

[radl33t]

Using windmills to generate hydrogen is hardly his idea, but in fact one that currently occupies many research groups with researchers that most people would probably not identify as stupid. As much as I would love to deride the 'argumenation' of your dutch CEO, may I simply point out that there are other methods for completing each and every step in your proposed scenario. I don't understand how you (or he) feel(s) this case is representative of the generic goal of using wind power to produce hydrogen locally. Furthermore, how is it incompatible with the gentile load[ing] and unload[ing] of hydrogen using metal hydrides? Why exactly can't they be incorporated into your hypothetical scheme to alleviate some of the problems you name? Lastly, don't you think it's a bit silly for you to chastise GP for making criticisms based on incomplete information when you do the exact same thing? Branding your post with your degrees in some vain search for credibility is embarrassing.

Nice Implementation of Older Idea

[BookRead]

I actually live in a building from the mid-80's that was built to use off-peak electricity. We got (and still have) a Time-of-Day electric rate where the we pay much less for the off-peak electricity. The ceilings in our units were designed as air plenums and were stocked with eutectic salt bags that change phase at about 68F. The idea is that that, in the summer we "freeze" the salt solution during the evening but cooling the air plenum. During the day we avoided running the A/C and saved significant electric costs. It works in reverse during the winter. They kept the apartments quite comfortable.

Eutectic salt solutions have been used in a lot of commercial applications to store "cold" generated during cheaper energy periods. The main disadvantage is that the eutectic salts break down over time and lose their phase change characteristics. There are also kind of expensive to replace.

Strategies like this that use thermal storage to modulate electric demand are pretty efficient ways to lower the required peak capacity of electrical systems. Other schemes like pumping water back up hill tend to run afoul of thermodynamic laws and can't be nearly as efficient.

Mostly ludicrous

[Ancient_Hacker]

Kinda ludicrous idea.

First of all, if you cool off the fridges, the increased temperature difference between inside and outside the fridge increases the rate of heat loss.

Next the larger the termperature difference, the greater the load on the compressors and the lower the overall efficiency. Although it helps a bit if it's cooler outside at night. But they're already capable of taking advantage of this without any "Night Wind" project babble.

The larger warehouses have more activity at night-- therfore more heat losses. The least best time for having a lower temperature.

A better approch would be to give somewhat lower rates for night electricity usage. Many industries use a *lot* of electricity and could save big bucks by shifting to nighttime work. There's one big steel-mill in town here that uses about 30% of all the electricity-- they'd love to get a few percent off their $13 million per month electric bill by using their electric arc furnaces at night.

Re:This doesn't matter with regard to wind power.

[Ziwcam]

The reason this matters for wind power follows:

Wind power is notoriously unreliable. A coal power plant can be predicted to always give out X amount of energy per minute (hour/day/whatever). Wind power, however, cannot. As weather is wont to do, it changes wildly and unpredictably during any given time span.

This method would allow cold storage units to use wind power to chill their goods during the night using "unpredictable" wind power, causing them to require less conventional power. That's how and why it works, in short. RTFA to figure it out if this doesn't help.

actual stored wind energy project

[gumbi west]

I had thought it was this project that actually stores off-peak power and then uses it during peak. It works based on this technology but uses wind power so that the variability can be managed.