The 7 best ways to stop load shedding

[duncan drennan]

I believe that if Eskom and the government work together, admit that they made a mess, and start being leaders, we can move through this energy crisis with only some minor bruises to our economy.

So I've compiled a list of the 7 best ways to stop load shedding. I believe that with some small and painless changes we can at least provide ourselves with enough breathing room to get through this crisis.

1. Turn off the air conditioners
2. Turn off your geyser
3. Turn off your pool pump
4. Turn off anything that consumes standby energy (TV's, DVD players, cell phone chargers, etc.)
5. Switch to CFL and LED lights (and use fewer lights)
6. Run appliances as late at night, or early in the morning as possible
7. Use your computers in energy saving modes

Read the full blog post for all the details of how and why

If you think this plan makes some sense, then please post about it on your blogs and websites! Let's try to spread a message that is understandable, and can get us out of our current predicament. Thanks

Also, post your energy saving tips here on The Forum SA

[Dave A]

Turn off the air conditioners

You live in Cape Town, don't you

[duncan drennan]

Well, as I've said before, would you prefer Eskom to turn them off for you?

The full article details how to minimise aircon effect on peak demand, and stay

It turns out that this is my most popular blog post so far (graded on traffic on the day of posting) - whoohoo! Also got a couple of interesting leads as a result of it. Must follow up now!

[Dave A]

Well, as I've said before, would you prefer Eskom to turn them off for you?

They already do

To some extent I'm revving you - it's really about using the aircon in moderation and only as necessary. Believe me, there are times when it is necessary.

I think we're going to have to talk about heaters come winter - when our real peak demand kicks in!

An idle thought about the 15% of Eskom power that goes to airconditioning - have you any idea how much of that is being used by the mines (who can't switch off their airconditioning and still operate)?

[duncan drennan]

To some extent I'm revving you

Yeah, I know....and I'm just revving back a little bit

An idle thought about the 15% of Eskom power that goes to airconditioning - have you any idea how much of that is being used by the mines (who can't switch off their airconditioning and still operate)?

It is probably quite significant! I hadn't thought about mines, but I did consider cold chains (food, drugs, etc.) that could not be turned off. Eskom's "conservative" estimate for peak savings is 600MW (which I used, and is from the National Response to the electricity crisis.

PS. posted a reply on my blog to your comment

[Dave A]

PS. posted a reply on my blog to your comment

You mean my comment got approved

Don't mind me - I'm just a bit whacky today

[duncan drennan]

Maybe you should turn your air conditioner back on.....

[murdock]

what about moving back into a cave or a mud hut next to a forrest and a river so you have plenty of fire wood and water.

i believe we should conserve energy but just because of some fools bad planning we must all now suffer

[duncan drennan]

I just got this comment on my blog, and the guy then called me and told me he has emailed over 300 people about this (DA, ANC, VF, Solidarity, and more). His attitude is really positive which is great to hear.

I have put my 2 geysers on swimming pool timers and my electricity bill was reduced with R460 the last 8 months average compared to the previous 8 months average.

My geysers are only switched on 1,5 hours in the middle of the night and again 1,5 hours in the middle of the day. We are 5 people in the house and have warm water all the time.

My usage also went down 44,4 % over that period (from average 2250 units/month to average 1250 units/month).

I have ignoramuses that belittled that. They even said it is impossible, my accounting is wrong etc. Even the technical director said in the newspapers that it does not work.

However, my accounts proves my point.

I have done my MBL at the School of Business Leadership, UNISA.

To me it seems quite clear how we landed in this situation (mismanagement and cost-cutting seem to be the culprits of our immediate demise), but how we respond to it will show our mettle as people of this country.

We have a great country which is certainly worth fighting for. Let's take these challenges head on with the resilience of the tough people that we are.

[Dave A]

I'm definitely hearing two sides to this geyser switch off story. If we look at the comment above, essentially the geyser is on for a total of 3 hours a day.

I don't doubt his facts and maths for a moment - one of the questions though is how much time is a geyser actually heating normally anyway. Applying very rough maths - about 6 hours in this case?

Those who are arguing that leaving the geyser on is more efficient than switching it off and reheating the water from cold are basing this on the fact that the cold heating element acts less efficiently than when it is up to normal operating temperature. This, too, is a fact.

Both are relevant to finding the optimal solution to using the least electrical energy to provide our hot water needs.

Frankly, two suggestions have made the most sense to me as bare minimums:

• Insulate - get a geyser blanket no matter whether you're going with the timer story or not.
• Go solar - even if it is a tiny panel on the north facing eave of the house that just tops up the heat during the day.

Both are relatively low cost, high yield and short-term-to-break-even solutions that will work well together.

Probably the thing that makes me the most nervous about the timer solution promotion is I just know that lots of folks are going to "do it yourself." If the sparks start to fly... It's not going to be pretty.

[IanF]

Those who are arguing that leaving the geyser on is more efficient than switching it off and reheating the water from cold are basing this on the fact that the cold heating element acts less efficiently than when it is up to normal operating temperature. This, too, is a fact.

Dave
How long does for a geyser take to warm up from cold, if you are on a timer should you put it on for 2 hours or more?

[Dave A]

No doubt it'll vary according to the type of geyser, but I suspect 1.5 hours is more than enough in most instances - at least judging by the time it takes for our geyser to recover from a full flush (about 45 minutes, but it's quite small - and old).

No doubt Duncan could give us a clue - assuming a 2kW heating element how many litres of water can be warmed 10 degrees in 10 minutes?

(Gee - in days gone by I knew the numbers to work that out off by heart. Getting old )

[duncan drennan]

• Insulate - get a geyser blanket no matter whether you're going with the timer story or not.
• Go solar - even if it is a tiny panel on the north facing eave of the house that just tops up the heat during the day.

Insulating certainly needs to be a priority for all households. The R150 investment will definitely save you money and pay for itself relatively quickly. Not too sure about solar - everything that I've seen is very expensive.

I'm a little unsure why this guy (in the comment above) is saving so much energy (and therefore rands). There are a couple of things that can play a factor like,

• Insulation
• Thermostat setting
• Usage

I've been trying to find some equations to do a quick calculation as to real savings and turning geysers on/off. Temperature setting will definitely play a role.

I can't see how the temperature of the element affects efficiency - it is a resistive heater and is nearly 100% efficient, regardless of temperature. It would be on for longer to heat from say 50º to 65º than from 63º to 65º, but I can't see how this effects efficiency.

The lower the temperature of your geyser the slower it will cool down.

Regardless of the energy issues, it is still important to try to turn your geyser off during peak times (07h00 - 10h00 and 18h00 - 20h00) to alleviate the load it adds to the electricity network. If you can turn it off all day and only turn it back on after 20h00 that will make a significant difference to load shedding.

____

PS. For those of you confused by this there is a difference between energy and power.

Energy is what you pay for and is measured in kilowatt hours (kWh). It is a measure of how long you have been using a certain number of kilowatts. So if your kettle is a 2kW kettle and you run it for 1 hour (yikes!) you will use (2kW * 1hr = 2kWh).

In this case the kettle's power rating is 2kW.

Eskom has a near infinite supply of energy but can only deliver a certain amount of power. Let's just say Eskom's power capacity was 20kW, that would mean that only 10 people could run their kettles at the same time, but there would always be enough energy to boil water, as long as only 10 people did it at the same time.

If 11 people tried to boil their kettle at the same time Eskom would not be able to provide the power for them to do so, even though they could provide enough energy.

This is exactly the problem that we have at the moment. Eskom has plenty of energy, but a limited capacity to supply power (their capacity is about 40000MW).

[duncan drennan]

No doubt Duncan could give us a clue - assuming a 2kW heating element how many litres of water can be warmed 10 degrees in 10 minutes?

I'm going to cheat here a bit....

It takes a 3kW, 150l hot water cylinder (HWC), or geyser, element to heat the water from 20 ºC to 65 ºC in the order of 2 hours 40 minutes and consumes about 7.838kWh

From Eskom's residential DSM page

Working backwards....45ºC change consumes 7.838kWH, which means 5.7ºC/kWh, or rather 0.17kWH/ºC.

So to work out how long it would take to heat from temperature a to b

time to heat = 0.17 divide by (element kW) times (b - a)ºC (approximately)

[Dave A]

I can't see how the temperature of the element affects efficiency - it is a resistive heater and is nearly 100% efficient, regardless of temperature. It would be on for longer to heat from say 50º to 65º than from 63º to 65º, but I can't see how this effects efficiency.

The resistance is not constant. The resistance is lower at lower temperatures, higher at higher temperatures. I've been messing around with some maths...

Consider the voltage as constant in the following.
Applying V = I * R, half the resistance produces double the current.
Doubling the current doubles the power demand applying P = V * I

Lower resistance at the appliance would also increase the effect of line resistance, energy dissipated at a non-target point, but that "should" be nominal.

EDIT: With an element resistance of the order of 10 - 20 ohms, line resistance could well be a factor.