Power situation long term?

[km2]

Eskom presentation on managing a power system

I did not go in expecting much from an hour long Eskom presentation, but that was actually really interesting. Thanks for posting it.

 

[oober]

I would posit that the *paying* customer base may start taking their business elsewhere.
If reliable Electricity isn't for sale, then self generation starts becoming more and more attractive, especially at current rates, and the pricing its heading rapidly towards. Its also going to be a lot more reliable than Eskom.

180k will get the average house with 20kw daily usage offgrid including batteries in todays money.
(Say about 5kw panels on the roof, and 30kw of battery, plus a 3kw backup generator to cater for repeated winter outages past 2 days of no sun, and all inverters etc for a single phase household)

Some Math / Justification on that
20KW daily usage = 830W/hr on average.
5KW panels will generate over 15KW in winter, and well over 30KW in summer daily, so deficit is 5KW/day or zero in summer.

Assuming 5KW / day worst case scenario deficit
You need roughly 3 x (3 days of battery) x 2 (50% discharge) for usage.
- Batteries shouldn't be drained past 50%, so halve the rated value.
- Cater for 3 days of worst case scenario of no sun.
- Add a generator for generation for worst case scenario getting worse, and batteries go below that point of discharge.

With that in mind, deficit is 5KW odd in winter, so 3 x 5 = 15KW for 3 days of discharge (say 3 days of cloudy weather) x 2 (can't discharge lead acid/agm/crystal batteries more than 50%) = roughly 30KW required in batteries.

28.8KW of battery can be had for a little over R1/Whr eg / 20x12v@120Ah= 28800W which can be run in 24V or 48V easily (battery inverters usually run in 24v or 48v sizing)

12v@120Ah Gel Lead Acid is currently R1500 at retail, or less, which = R30,000 for 28.8KW per 5 years usage worse case.
The good news is that battery prices are headed down, not up.

...

I think your battery sizing is a bit optimistic. You need to account for efficiencies of about 85% and also your inverter will use 40-60W/h.

Taking that into account with 20 20x12v@120Ah= 28800W@48V * (0.85) = 24480W / 2 for 50%DOD = 12240W.

Now add the inverter usage itself lets say 50W = 1200W per day x 3 = 12240W - 3600W = 8640W / 3 days = 2880W actual available. So a shortfall of 2120W per day. You need a battery bank that is at least 43% bigger. Let's make it 50% to be safe, so your R30,000 becomes R60,000. ROI starts to get much smaller. That is why net metering is actually so important. Otherwise it might just not we worth it.

Also I'm not sure how much power solar panels produce when it's raining or very cloudy? With the stated battery bank if your solar is not generating much you only have about 120W per hour at your disposal for the 3 rainy days.

Also it's not recommended to have so many parallel batteries, for some reason, they all seem to recommend getting bigger 2V batteries and running the whole lot in series. So you would rather want to get batteries like these.

The 762aH batteries cost about R3000 each and weighs in at 55kg...

So lets just say your solar panels only produce 5KW total per day for those rainy days, I'm totally guessing this figure. And your usage is still 20KW that is a shortfall of 15KW per day that needs to be stored in your battery bank.

So we need a battery bank that will last us 3 days, which is 15KW * 3 = 45KW.
Lets first just work on 1 day of required power of 15kW.
Lets use the 762aH 2V batteries, we will required 24 of these batteries to get to 48V. This will give us one battery bank of 762aH@48V = 48*762 = 36576 * (0.85) = 31089,6W.

This is still at 100% DOD so we need to half that to get to 50% which gives us 15545W per day. Remember the inverter will use about 1200W per day so you only get 14345W.

The costs is then R3000*24 = R72000! Only for one battery bank. Now we want 3 days worth of power so need two more banks in parallel. That gives us 72 batteries required. 72xR3000 = R216,000.

I'm probably very pessimistic with my calculations...

 

[Arthur]

I did not go in expecting much from an hour long Eskom presentation, but that was actually really interesting. Thanks for posting it.

You know, Eskom is being unfairly blamed on this fiasco.

There are tens of thousands of highly committed and competent people at Eskom, who do an incredible job with aging plant and infrastructure.

Ironically, their woes stem from SA's 'honeymoon' period - the 5-6 years after 1994 when all new projects were put on ice because Eskom was going to be broken up and sold off.

That is not Eskom's fault. It made the case, but it was not listened to.

It is the fault of our political overlords.

If I were an Eskom board member, I would make damn sure just about every worker, manager, engineer got a huge bonus. These people are performing a miracle holding together a very creaky system - and that creakiness is not of their making.

In the real world, we should be deeply grateful to the thousands of professionals at Eskom who are managing an incredibly difficult situation with great skill.

They deserve medals, in my view.

 

[LazyLion]

Eskom is very blameworthy. They got rid of competent people and have failed to carry out preventative maintenance.

 

[oober]

You know, Eskom is being unfairly blamed on this fiasco.

There are tens of thousands of highly committed and competent people at Eskom, who do an incredible job with aging plant and infrastructure.

Ironically, their woes stem from SA's 'honeymoon' period - the 5-6 years after 1994 when all new projects were put on ice because Eskom was going to be broken up and sold off.

That is not Eskom's fault. It made the case, but it was not listened to.

It is the fault of our political overlords.

If I were an Eskom board member, I would make damn sure just about every worker, manager, engineer got a huge bonus. These people are performing a miracle holding together a very creaky system - and that creakiness is not of their making.

In the real world, we should be deeply grateful to the thousands of professionals at Eskom who are managing an incredibly difficult situation with great skill.

They deserve medals, in my view.

If only they would help fast track feeding back into the grid! Then I'd give the the purple heart

 

[Arthur]

Eskom is very blameworthy. They got rid of competent people and have failed to carry out preventative maintenance.

On the maintenance, they had no other choice. The instruction to run at the red line comes from their political masters. I know for a fact that Eskom management wanted to bring down baseload systems for essential maintenance and refurbishment, and their only shareholder refused.

They didn't get rid of competent people. When top experts saw the reality of political control, they left of their own accord, and who can blame them. They knew it was a sinking ship, and that they would be blamed for the faults of others.

Seriously. This catastrophe is caused by the State, not Eskom.

 

[Arthur]

If only they would help fast track feeding back into the grid! Then I'd give the the purple heart

This is a complex technical problem for them. With the grid so unstable, the very wild swings of PV feed-in can push the grid over the edge. Especially in the two daily peaks, exactly when solar PV drops away to zero.

I speak as someone who has solar PV and who does export to the grid.

 

[Jola]

Hmm, I have heard stories of competent white engineers being sidelined, even now, purely because they are not black.

IMO a lot of the blame lies at Eskom's door.

 

[Arthur]

Again, that type of AA is imposed on them by the State. It is not homegrown.

Until Eskom was nationalised in 2002, it ran a very sane fair employment policy. That policy was introduced and managed in the 1980s by Herman Edeling, a world class engineer and manager, who also headed up both generation and transmission, building it into one of the best systems in any utility anywhere on the planet.

I have heard from his own mouth how this worked, and how the State increasingly imposed impossible and irresponsible targets.

Why do you think Brian Gilbertson, a very capable private sector manager, lasted less than two years as GM? He saw the problems were not internal (he could fix them if they were) but external.

 

[Venomous]

so is this a uniquely African problem?

no.

The UK have been taking coal plants off the grid, in an attempt to go green on electrical production. Replacement green plants are not producing enough/not completed etc, etc.

They have been issues with warnings regarding possible electrical down times for this winter...

 

[HAL 9000]

South Africans are warned to brace themselves for cold turkey on Christmas Day as the Eskom crisis looks set to continue into the New Year, reported the Sunday Times.

According to the newspaper, consumers can expect 54 hours of darkness in the coming week as the embattled parastatal announced that it needed to free up 4,000MW after running out of water and diesel at some facilities.

CEO of the South African Chamber of Commerce and Industry Neren Rau said the country’s unstable electricity supply was the single biggest risk to the country’s economy.

However, the Sunday Times established that cabinet is set to meet on Wednesday over the issue, that municipalities are being slapped with damages claims in the millions from consumers over power surges brought on by faulty equipment and outages, and that several disaster management centres are on high alert to deal with the unforeseen impact of the crisis.

Meanwhile, Eskom CEO Tshediso Matona is scheduled to provide an update on Monday on the parastatal’s action plan and to release its festive season forecast, reports the newspaper.

This comes after months of drama at various power stations including the recent collapse of a silo at Majuba.

Eskom announced on Friday that it had implemented stage three rolling blackouts that would last until 22:00 on Sunday.

It said power cuts would begin at 06:00 and end at 22:00 on Saturday.

On Sunday load shedding would also last until 22:00 to build up reserves for the upcoming week.

Eskom chief executive Tshediso Matona said: "Our objective for load shedding this weekend is to fill the pumped storage dams as well as the diesel tanks and undertake essential maintenance.

"We're trying to avoid load shedding if at all possible until mid-January."

The power utility could not guarantee that, but said it would put in every effort over the festive season to avoid interruptions, he said.

"Due to technical problems at its power stations, depleted water reserves and logistical issues relating to diesel supplies at its peaking power stations, Eskom's power system was extremely constrained," the parastatal said.

As a result stage two power cuts were implemented at 11:00 on Friday and it was extended to stage three an hour later.

"The change in stages is due to the shut-down of two of our open cycle gas turbine power stations that use diesel to generate electricity," Eskom said.

"The diesel reserves have been depleted at the Gourikwa and Ankerlig gas turbines leading to the shut-down of the power stations."

"This in turn led to the Drakensberg and Palmiet pumped storage schemes, which use water to generate electricity, to reduce their output as a result of depleted water reserves," Eskom said.


http://www.fin24.com/Economy/Eskom-chaos-set-to-dampen-Christmas-festivities-20141207

 

[Mortymoose]

Hey my power in the store went off for 3 seconds there, will you South Africans stop messing around with "our" power....

/Moose realizes to late that he might irk some folk.....

On a serious side, google Kudu Gas Power station. This was meant to be built in my remote town and should have been up and running by now..... not a big plant, a mere 800MW , enough for the entire Namibia with an extra 200-300Mw to sell off.

At one stage ESKOM did'nt want to buy from us if we built the plant, then the project stalled and started, then stalled and started.

Over the years there were numerous bigwigs from Nampower in our town, telling us how this plant would make us self sufficient.....

Then as the years dragged on and certain people did'nt get what they wanted, reports started surfacing that the project was off then it was on, then it was off.... now last week, it was back on again.....

If africa could see past the idea of "what's in it for me?" we would have been able to give back 800mw of power into your SA grid..... but as with all things African....... we are still waiting.....

 

[HAL 9000]

Sir David Attenborough (whispering):

"And here we see Eishkom's PR representative, Isay Notruth, hard at work behind his 'Haikona-No-Spark' manual typewriter, furiously drafting their official response as to the REAL reasons for the 'current power crisis' (pun intended) in South Africa - to be tabled at the special Cabinet meeting scheduled on Wednesday!"



"A full sitting of Parliament is expected for this momentous & de-lightful occasion, which will hopefully shed some light on the current crisis affecting all of South Africa!"



"Rumour has it he has included an 'Eish-breaker' to make his presentation more entertaining, and hopefully a few Cabinet Ministers will also 'crack-up' when hearing this!"

 

[satanboy]

You know, Eskom is being unfairly blamed on this fiasco.

There are tens of thousands of highly committed and competent people at Eskom, who do an incredible job with aging plant and infrastructure.

Ironically, their woes stem from SA's 'honeymoon' period - the 5-6 years after 1994 when all new projects were put on ice because Eskom was going to be broken up and sold off.

That is not Eskom's fault. It made the case, but it was not listened to.

It is the fault of our political overlords.

If I were an Eskom board member, I would make damn sure just about every worker, manager, engineer got a huge bonus. These people are performing a miracle holding together a very creaky system - and that creakiness is not of their making.

In the real world, we should be deeply grateful to the thousands of professionals at Eskom who are managing an incredibly difficult situation with great skill.

They deserve medals, in my view.

Fine, but I can't see why the CEO is paid R22m. His salary should be reduced to R4-8m.

 

[HAL 9000]

Fine, but I can't see why the CEO is paid R22m. His salary should be reduced to R4-8m.

NO parastatal CEO (essentially a Government sub-department as they are the majority shareholder) should earn MORE than Numma Whunnnnn - they should be paid the same amount - or less - than the Cabinet Minister in charge of the portfolio for the relevant parastatals.

 

[Space_Chief]

They can offload some of this demand by introducing LPG heating for cooking and water heating though. At least in Europe they have that.

 

[saturnz]

I'm generally not pessimistic about our prospects, but when Tina was appointed energy minister my heart sank and I knew what would unfold.

For some bizarre reason and counter to their own experts who they hired, government is going nuclear. Nuclear plants are difficult to budget and are guaranteed to run into huge overruns of more than double the original budget, moreover they take foreever to build, 10-15 years in practise, if not longer.

The United States is an excellent example of the practical considerations of building nuclear plants, and thats with reasonably good intentions. Given the fact that Tina is minister now, I think its not even worth considering how much a failure our nuclear programme will be, and essentially that means this problem is not going to go away in the next decade or two unless something seriously dramatic happens, politically or otherwise.

 

[atomcrusher]

From the horse's mouth - Zuma comments of the power situation

Our less than esteemed President speaks on the power situation ..

More needs to be done with less in order to balance the country's finances, President Jacob Zuma said in written replies to Parliament on Monday.

"We are fighting wasteful expenditure and corruption. We are also freezing budgets of non-essential goods and services, withdrawing funding for posts that have been vacant for some time, and reducing the rate of growth of transfers to public entities, particularly those with cash reserves," he wrote.

http://today.moneyweb.co.za/article?id=798380#.VIak6TGUeRs

 

[itareanlnotani]

I think your battery sizing is a bit optimistic. You need to account for efficiencies of about 85% and also your inverter will use 40-60W/h.

Taking that into account with 20 20x12v@120Ah= 28800W@48V * (0.85) = 24480W / 2 for 50%DOD = 12240W.

Now add the inverter usage itself lets say 50W = 1200W per day x 3 = 12240W - 3600W = 8640W / 3 days = 2880W actual available. So a shortfall of 2120W per day. You need a battery bank that is at least 43% bigger. Let's make it 50% to be safe, so your R30,000 becomes R60,000. ROI starts to get much smaller. That is why net metering is actually so important. Otherwise it might just not we worth it.

Also I'm not sure how much power solar panels produce when it's raining or very cloudy? With the stated battery bank if your solar is not generating much you only have about 120W per hour at your disposal for the 3 rainy days.

Also it's not recommended to have so many parallel batteries, for some reason, they all seem to recommend getting bigger 2V batteries and running the whole lot in series. So you would rather want to get batteries like these.

The 762aH batteries cost about R3000 each and weighs in at 55kg...

So lets just say your solar panels only produce 5KW total per day for those rainy days, I'm totally guessing this figure. And your usage is still 20KW that is a shortfall of 15KW per day that needs to be stored in your battery bank.

So we need a battery bank that will last us 3 days, which is 15KW * 3 = 45KW.
Lets first just work on 1 day of required power of 15kW.
Lets use the 762aH 2V batteries, we will required 24 of these batteries to get to 48V. This will give us one battery bank of 762aH@48V = 48*762 = 36576 * (0.85) = 31089,6W.

This is still at 100% DOD so we need to half that to get to 50% which gives us 15545W per day. Remember the inverter will use about 1200W per day so you only get 14345W.

The costs is then R3000*24 = R72000! Only for one battery bank. Now we want 3 days worth of power so need two more banks in parallel. That gives us 72 batteries required. 72xR3000 = R216,000.

I'm probably very pessimistic with my calculations...

Don't forget I cater for the longer term rainy days (which aren't that often) with a generator.
It's cheaper to run a generator if needed for the odd three days of continual rain/overcast weather in winter for 3-4 hours to recharge batteries a day, than to buy more batteries.

You don't need to cater for the occasional once every few month situation with an investment in a bunch of $$ batteries. Cater for outliers with sensible solutions!

My own figures are actually based on a year of actual usage, vs theory, so should hold up well for those in the Cape, as thats where I've been running my own system. Even on the crappiest days I don't remember getting < 10KW with a 4KW setup on the worst days, which was slightly more than ample for our daytime + generated a little excess.
When I'm back I can pull actual values from my records, and verify that (I'm in Shanghai at the moment), so hard to check.

I could go into what batteries and why, but it would go into pages upon pages of explanations.
Parallel = thicker cabling, as the ampage goes up. Serial = same size cabling as voltage goes up. Battery cabling is a once off, and worth spending the money for getting that right. Its also a fairly minor part of the system pricewise. Panels to inverter usually run higher voltage DC, as they are longer runs, Battery<-> inverter is typically short and run in high amps.
I'm not such a fan of 2V batteries for larger installs. Suffice to say I'm generalizing somewhat, but its fairly feasible to use what I suggested. 12v is also the most produced, so economies of scale means that they're the best priced.
Again, this is glossing over things somewhat, but I really can't be bothered going into detail (sheer laziness I know!). Probably worth a blog post on my blog


IMHO Its better economics to oversupply on panels vs batteries, as batteries can be recharged faster with more panels. Having excess panels means oversupply of electricity in summer (which is a bit of a waste as we can't feed back to the grid*), and ample supply in winter. Panels also last 20+ years, and are the cheapest part of the system.

Monetary decisions typically decide whats best, vs theory, as you can probably see from inferring the thought patterns involved in the decisions above, and my explanations for them.


It also lets you look at things in a different way.
Not so hard to imagine situations like -

Honey, if you run the washing machine today, we need to run the generator at R30/hr, can you wait a few days?

Or

Hmm, if we bought a more efficient energy saving fridge, we'd save at least 50W/hr, thats 36KW/month or R700 a year, and we wouldn't need additional battery.

When you monetize costs into capital expenditure vs general expenditure it suddenly makes a lot more cents (sic) to do thing like that.
----

*Allegedly yes, reality - not economically feasible, or easy to do.

 

[DominionZA]

http://www.makro.co.za/sports-and-o...re-/br-saturn-580-4-burner-gas-braai-275471EA

Got one of these from my wife in Aug for my birthday. Awesome!