Load Shedding does not work

[Moederloos]

I have a prepaid meter - so for me it is relatively easy to get the figures I am about to quote. I would be interested in other people's experience / observations.

I use 35KW of power per day - every day. This figure seldom fluctuates much, and whenever I buy more, I do a quick calc again over the "billing period", and it is 35KW per day. That translates into about 2KW per hour for the 16 "awake" hours per day, and 3KW for the 8 "sleeping hours".

Now, yesterday, our power was cut from 11am-2pm - 3 hours. In theory, this should have removed 6KW from the grid. However, when the power returned, my usage spiked - I used almost 4KW in under 40mins. By 3:30pm (90 mins after power was restored) I had used 7KW. In other words, my usage in 90 mins was double what it would have been had there been no load shedding to begin with, and my overall consumption was not diminished in any appreciable way.

For the curious, this power use was all related to "always on" equipment like fridges (which were now hot), geyser (which was now cold), UPS (which were all flat) and so on. I did switch the kettle on, but this was the only "active" power use on my part.

Anyone else notice this trend or have figures we can see?

 

[eltherza]

Anyone else notice this trend or have figures we can see?

Well, think of it like this. Which is harder to do, push a car from stand still or push a car that is already moving? I believe the same applies for everything in your house.

Another example. Your fridge is smart that when it increases 1 degree from the level it's set, it takes 10mins to lower it that 1 degree. During load shedding, your fridge would increase 4 degrees, thus taking 40mins later decrease the degrees again. Have you saved power? No. But what load shedding DOES stop is things that aren't automated, such as TVs, lights.

Of course that is stupid to, people will just change the times they watch TV, do washing and cooking.

The whole "pre-emptive" load shedding isn't to save coal for winter, it's because they cannot produce enough power at the time for everyone. Saving coal is a joke because everyone will just change when they use the power.

 

[*New* *Improved* chiskop]

Moederloos, I have no idea about my own usage but I'm interested in your figures. Why do you think you're using more power during the eight sleeping hours? Is that the geyser?

As an aside, my parents used to have a prepaid system in a holiday house. One day it stopped debiting our usage. For about two years they were running off the same R20 pre-paid electricity. My father's argument was that it would be expensive for Eskom to come out to resolve the problem, and that it would take them years to recoup that cost, seeing as the house was only occupied about two months of the year.

After about two years, the meter started running again with no intervention.

 

[Moederloos]

Moederloos, I have no idea about my own usage but I'm interested in your figures. Why do you think you're using more power during the eight sleeping hours? Is that the geyser?

Its 3KW over the entire 8 hours, or about 0.4KW per hour. Not 3KW per hour over the 8, or 24KW.

It is of course a bit of a guess (its close to accurate), I tried to divide the 35KW over 24 in a way that "made sense".

 

[zambussi]

Aah, but here's what you're missing. Load shedding is not in place to save overall electricity consumption, but rather to stagger it since almost 25% of the network is down due to non-existent maintenance.

So when your power comes back on line, yes you will use more power, but mnay businesses which account for the majority of power usage will have closed by 6PM, so there is spare capacity.

Of course if Eishkom hadn't been in such a hurry to purge skilled white staff in the past, we wouldn't be in this mess - but nothing we can do about that now - especially since their masters haven't learnt anything from this fiasco.

 

[Moederloos]

Aah, but here's what you're missing. Load shedding is not in place to save overall electricity consumption, but rather to stagger it since almost 25% of the network is down due to non-existent maintenance.

So when your power comes back on line, yes you will use more power, but mnay businesses which account for the majority of power usage will have closed by 6PM, so there is spare capacity.

Of course if Eishkom hadn't been in such a hurry to purge skilled white staff in the past, we wouldn't be in this mess - but nothing we can do about that now - especially since their masters haven't learnt anything from this fiasco.

There's the rub - my power returned at 2pm. Just in time for "them" to now be required to loadshed the JHB CBD. So, in short, the load shedding of the CBD was required, due to the excess power usage in Roodepoort, which in turn was required, because at 10am Sandton (or wherever), came back on and used an excess in power...
And, when the CBD came on at 6pm, the Florida/Maraisburg section went off - until 10pm.

So, the staggering is not even useful - it is worse than useless as it just concentrates 3-4 hours of power usage into 90mins.

 

[AutoX]

I think you are onto something Moederloos, I really do.

 

[diabolus]

Well the fact that we -never- know for sure when Eskom plans to load shed also means, we don't plan/spread our usage around it . So when we get load shedded it is generally case that you did not do what you wanted to do [i.e. heat the water / cooking / etc] . So what happens when the power comes back on? You turn on ALL your stuff [catching up on 2 hours+ of no power basically] = a big spike. If i knew with 100% certainty on day x, from time x-y i won't have power, i might have done a few things earlier
or spread them out around the time without then having to turn -everything- on the second the power comes on.

It's the same thing at work. We -can- actually function without power if we know about it, we have tons of meetings which are perfect to be held in power outage moments....but we simply can not plan it as Eskom just seem to load shed when the hell they feel like it.


I thought Eskom was onto something when they said they will Loadshed areas regardless of whether there are enough power [ensuring a consistent schedule], but they then simply pulled out of that one saying "there's enough power"...2 days later blam power goes randomly again. So Eskom is a bunch of morons combined with municalities...or whoever is suppose to plan these things properly.

 

[Moederloos]

Well the fact that we -never- know for sure when Eskom plans to load shed also means, we don't plan/spread our usage around it . So when we get load shedded it is generally case that you did not do what you wanted to do [i.e. heat the water / cooking / etc] .

...

So Eskom is a bunch of morons combined with municalities...or whoever is suppose to plan these things properly.

Two good points I often debate. The first is a real pain - yesterday the power went out at 10:52 - instead of 10. (am). So, at 10am I need to go out - turn off PC. Get back at 10:40 - power is on. So, I turn everything on - only to have the power kill everything 10 mins later.
The local Spar lost an entire day's baking - they put bread and rolls in the oven at 10:30, thinking the power would not go off that day.
And I am sure the problem is not localised to my experience.

As to the municipalities being moronic. So true. Power comes on at 2pm - and despite our area having ripple switches - they allow the geysers to all be on. Huge spike in usage.

 

[Daveogg]

Have to agree here, in fact i think the load shedding i am experiencing is actually making the situation worse.

Take for example my swimming pool pump, which i have set to NOT run during the morning or evening peak. Eskom in its wisdom load shed me from 12 - 2:20pm, thereby disabling the timer on my pump. When the power comes back on, the pool pump starts again and is in use for the same number of hours as it would have been, except it is now running during peak periods.

Similar for a whole host of other power using appliances.

 

[HavocXphere]

You stated that your hourly usage is about 2kW.

By loadshedding you they effectively cut 6KW (2 x 3 hours).

During the 1.5 hours afterwards, you used 4KW over and above your normal usage (7-1.5x2).

That's 2KW "saved" on your house alone.

That's significant amount when demand is getting close to supply.

There's the rub - my power returned at 2pm. Just in time for "them" to now be required to loadshed the JHB CBD. So, in short, the load shedding of the CBD was required, due to the excess power usage in Roodepoort, which in turn was required, because at 10am Sandton (or wherever), came back on and used an excess in power...

Your chain reaction theory only works if the total usage increases, which by your numbers it does not and there are no peak periods, which there are. With a total decrease and the presence of peak periods, the benefit of moving usage into non-peak periods and total savings outweighs this effect of one load shedding triggering another.

 

[Moederloos]

You stated that your hourly usage is about 2kW.

By loadshedding you they effectively cut 6KW (2 x 3 hours).

During the 1.5 hours afterwards, you used 4KW over and above your normal usage (7-1.5x2).

That's 2KW "saved" on your house alone.

That's significant amount when demand is getting close to supply.

No - because for the rest of the 3 hours (1.5 hours), I used the regular 2KW.
So, I used 7KW in 3 hours as opposed to the normal 6. An INCREASE of 1KW.

At best, I came out equal - but! at the expense of a concentrated load for 1.5 hours.

 

[Deenem]

Sorry to be pedantic, but you used 35 KWH per day, not 35KW.

Think of a 35KW engine running for an hour, the energy that it produces in that hour is 35KWH and that's how much you used during the day.

Otherwise, I think you have a valid point, there will definately be a surge everytime the power comes back on and everthign starts to 'catch up'

 

[killadoob]

can they store electricity?

i mean ould they shut the whole of Gauteng down from 2-4am would this make a difference?

 

[HavocXphere]

No - because for the rest of the 3 hours (1.5 hours), I used the regular 2KW.
So, I used 7KW in 3 hours as opposed to the normal 6. An INCREASE of 1KW.

At best, I came out equal - but! at the expense of a concentrated load for 1.5 hours.

Here's how I worked out 2KW. Maybe my calc is wrong:

Without loadshedding
Day: 16 hours x 2 = 32 KW
Night (8hours): 3 KW
Total hours: 24
Total usage: 35

With loadshedding:
Day:
->3 hours loadshed: 0 KW
->1.5 increased usage: 7 KW
->11.5* normal: 23 KW
Night(8hours) 3 KW
Total hours: 24
Total usage: 33

35 - 33 = 2 KW savings

*=24-8-3-1.5=11.5 hours

 

[Moederloos]

Here's how I worked out 2KW. Maybe my calc is wrong:

Without loadshedding
Day: 16 hours x 2 = 32 KW
Night (8hours): 3 KW
Total hours: 24
Total usage: 35

With loadshedding:
Day:
->3 hours loadshed: 0 KW
->1.5 increased usage: 7 KW
->11.5* normal: 23 KW
Night(8hours) 3 KW
Total hours: 24
Total usage: 33

35 - 33 = 2 KW savings

*=24-8-3-1.5=11.5 hours

OK - fair enough. Next load shed I will keep usage figures for 5-6 hours to see how long it takes to stabilise completely.
However, the point remains that for 1.5 hours I used around 4 times my normal usage - which surely defeats the whole purpose of load shedding to begin with. In other words, Eskom are forced to load shed another area just to accommodate the increased strain on supply, caused by my having been loadshedded to begin with!

 

[Frankie]

OK - fair enough. Next load shed I will keep usage figures for 5-6 hours to see how long it takes to stabilise completely.
However, the point remains that for 1.5 hours I used around 4 times my normal usage - which surely defeats the whole purpose of load shedding to begin with. In other words, Eskom are forced to load shed another area just to accommodate the increased strain on supply, caused by my having been loadshedded to begin with!

Load shedding is not there to save on your bill or overall consumption, but to relieve the inability of Eishkom to meet the instantaneous load demand with the limited number of generators they have available.

 

[Moederloos]

Load shedding is not there to save on your bill or overall consumption, but to relieve the inability of Eishkom to meet the instantaneous load demand with the limited number of generators they have available.

Which is my point - it fails in that task.
If my load increases 3-4 fold after power is restored, they are exasperating the problem by shedding in the first place!

 

[stoke]

I completely agree with you Moederloos, I sit here watching my UPS's recharge and hear the fridge running full speed and the freezer sprinting at full speed, and of course, when the power comes back on immediately one cuppa tea/coffee is required.

This is more like spike enforcing, not load shedding.

 

[HavocXphere]

1.5 hours I used around 4 times my normal usage

Valid point there. Its more than double (2.5X). So they would need to loadshed 5 areas for every 4 they loadshedded in the previous hour/period. However, if the loadshedding hours are long enough, then a single round of loadshedding can move the entire thing into off-peak...where the eventual spike matters less.

You're right in that its not as clear-cut as it seems, but they are not exasperating the problem. If demand approaches supply then they *must* loadshed to prevent a cascading grid collapse. No choice.