From: "Geo." 

We've diverted from the goal. They are looking for energy storage
techniques, big batteries.

I was thinking of freezers like a house, more insulation means less energy
usage. They don't care about that, they want to cut the peaks off peak
energy usage.

Here in Ohio they use time of day billing to do that. Electricity at 7am is
more expensive than electricity at 5am. They also bill for sharp increases
such as turning on all the lights in a big building at the same time, if
you spread out the load increase over a couple hours it costs you less.

Geo.

"Don Hills"  wrote in message
news:a2B2FtgaXekG092yn{at}attglobal.net...
> In article , "Geo."
 wrote:
>>
>>Well if that's true, then just put stuff into the freezers at off peak
>>electrical usage times.
>
> Costs more in delivery scheduling. You need more trucks etc. Twice as many
> trucks if you can only deliver for 12 hours of the day instead of 24, for
> example.
>
> But now you've started me thinking: Frozen goods are normally "blast
> frozen"
> at point of manufacture, then carried in refrigerated containers / trucks
> to
> the cool stores if they aren't geographically adjacent. (Even if they are,
> they have to be later transported from the factory to the distribution
> depots.)
>
> A lot of energy is used to quick freeze the goods (literally, blast them
> with extremely cold air) to get them over the phase change. Assuming goods
> with a high water content, and assuming an initial temperature of 20
> degrees
> C and a final temperature of -20 degrees C, the enrgy required is divided
> up
> roughly as follows:
>
> 17% to drop the temperature from 20C to 0C.
> 66% to freeze the goods.
> 17% to drop the tempearature from 0 to -20C.
>
> The goods are usually transported at about this temperature or a bit
> higher,
> truck/container insulation is kept as thin as practical to maximise load
> space.
>
> Long term storage warehouses keep the goods at -24 or less in some cases
> to
> maximise storage life. That's only a drop of 4 to 6 degrees from the
> truck,
> not a huge energy difference.
>
> The other type of "cool store" is that for fruit and vegetables,
> especially
> the ones used for keeping apples etc for months at a time. They run above
> freezing, but usually do the full pull-down at the store rather than at
> the
> packing house.
>
> So it looks like a significant part of the energy consumption is at the
> blast
> freezing stage for frozen storage. It would make sense to do that "off
> peak",
> except that again you run into problems with inefficient utilisation of
> plant.
>
> --
> Don Hills    (dmhills at attglobaldotnet)     Wellington, New Zealand
> "New interface closely resembles Presentation Manager,
> preparing you for the wonders of OS/2!"
>    -- Advertisement on the box for Microsoft Windows 2.11 for 286

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