Author Topic: Cutting through the BS for alternative power  (Read 12303 times)

Offline chrisc

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Re: Cutting through the BS for alternative power
« Reply #15 on: February 08, 2015, 06:46:48 PM »
As an aside, here is a reprint of an article which appeared in a financial magazine in January

The view below is from an Eskom engineer . (1977 to 2004)

Eskom (when it was the Electricity Supply Commission) was one of the best companies in the world.
It was owned by all South Africans, and was a non-profit making organization.

Money was always set aside, by selling electricity for more than it cost to produce, making profit for replacement and expansion.

No World bank or Government loans)

In 1994  it was turned into a business with the government as sole shareholder.
This was done to collect further tax from those who actually pay for electricity, and to provide a vehicle for the implementation of government policies in the form of job creation and black empowerment.
Profits, and the money set aside for replacement and expansion and maintenance, was paid to the government as dividends.
The sole 'shareholder' directly appointed most of the executive, and non-executive directors.
These appointments came out of the ranks of the ANC, and were people with no managerial or Power Plant experience.
The people started getting appointed & promoted based on potential.
They couldn't perform the work, but, the people who could do the work, but were retrenched based on skin color, were re-employed as contractors.
Although no additional work was getting done, (due to lack of funds because of the increased work force of roughly 23%) this was fine because the government wanted to reduce unemployment.
In order to bring relieve to poverty stricken townships,

Eskom directors were instructed to produce the cheapest electricity in the world.
This plan did not work, because of all the extra wages, contractors, and a Management team that did not have a clue how to run a Power plant,
Resulted in ESCOM  running into huge losses for the first time in history.
To compensate for this, the non-competent management team cut the maintenance budget by 55%
This were the first “cracks” in the once stable, profit making Power giant’s foundation.
The sole shareholder in the Mbeki era, wouldn't allow Eskom to build any further power stations,
saying that this would be done by private investors.

The private investors didn't come to the party because electricity was too cheap (remember the reduced fee for the poverty stricken masses) to provide adequate return on investment.
Five years too late Eskom was allowed to expand and build 2 huge, new power stations, but it didn't have any money. . .
This had to be borrowed.

The reason for this was that the ANC government instructed ESCOM not to cut the power to non-paying black townships, resulting in HUGE losses. (In the 2014-2015 book year, Soweto was R670 million in arrears, with more the than 5.2 million illegal aliens)
The “New” black uneducated, and with no experience, signed a contract with the Richards bay Hillside Smelter to deliver 120 MW of Power, for 25 years (who in his right mind would sign a contract for such a long period?)
At a reduced cost of 27% of the real cost of electricity. ( 120 MW is enough power to run a City the size of Vereeniging)
The ANC, the sole shareholder wanted a piece of the cake (the two new Power plants) and 'got' a big piece of Hitachi - the company who 'won' the contract to supply the boilers for these power stations.
Because of this Eskom wasn't allowed to take Hitachi to court when poor, sub grade materials were supplied.
Then Eskom, with it's reduced standards, attempted to project manage the construction of these new power stations by itself.

What a calamity !!!!!
The money was borrowed from the world bank, however because they are coal stations a requirement was the installation of flue gas desulphurisation.
This hasn't happened (yet) because of insufficient water. So Eskom (they don’t mention the ANC Government) is in trouble with the world bank.
In short, because of taxation, affirmative action, transformation, employment, equity, BBBEE, lots and lots of corruption and a bloated and bureaucratic workforce etc,
Eskom has run out of money and generation capacity, standards have dropped dramatically,
corporate memory is being lost at an alarming rate due to “forced” retrenchments of skilled, qualified white persons with years of experience.

Today Eskom is attempting to borrow the money for the steam generator replacement at Koeberg from a French bank.
One of the questions that this bank is asking is about post Fukushima safety improvement progress.
Guess what !!!!! 
Because there is no money ..........as is always the case, SOMEONE must pay. So Eskom wanted to dramatically increase its price.
The government (who is also the sole shareholder) wouldn't allow an increase large enough to cover the cost of its mismanagement.

So Eskom is bankrupt,
And, there is no money for maintenance, so the situation will carry on until total break down is the last resort.

Offline chrisc

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Re: Cutting through the BS for alternative power
« Reply #16 on: February 10, 2015, 06:46:28 PM »
Mantech have a range of inverters, cost is about 20% less than the suppliers above

An electronics shop in China Town sells inverters.  I am going along there tomorrow with this friend and some measuring instruments to see if they are within spec

Offline LeonardF

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Re: Cutting through the BS for alternative power
« Reply #17 on: February 10, 2015, 08:41:53 PM »
Hi All

I have been looking for options to combat the load shedding problem. The generator vs A UPS solution.

Just basically want to power up a PVR decoder, TV, ADSL router and a DVD player. Probably about 175 watts. It would be great to also be able to have a few lights at night although some battery backup lights could suffice.

I was quite keen on the UPS solution as it seemed the most convenient to implement but I realise that they do not really have decent storage (Battery power) to run for 4 to 5 hours. After all they are mostly designed for 15 to 20 minutes

i.e. a 3000VA UPS plus additional battery bank
http://www.purpleflytrading.co.za/rct-c-316_93229/rct-3000gt-online-ups-2400w-single-phase-with-ground-lcd-display-1-x-rs232-1-p-2989462.html
and the battery bank
http://www.purpleflytrading.co.za/rct-c-316_93229/rct-extended-battery-bank-for-3000gt-online-ups-12v9ah12-rct3000gtb-p-2989526.html

At R8.2k it is becoming quite an expensive solution

I also came across a UPS on the Communica website
http://www.communica.co.za/Catalog/Details/P0751533767
I see it is a pure sine wave which I assume is the desired output.
It seems this unit is designed to take a 12V 120 to 150Ah battery which should do the job. Mantech has a 150Ah battery for R3.3k

Is this setup practical?

Has anyone gone this route?

Are there other options worth considering?
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Offline Atjan

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Re: Cutting through the BS for alternative power
« Reply #18 on: February 10, 2015, 10:01:15 PM »
Thanks for that link Chris. There really is a lot of BS around on the alternative energy front. I'd appreciate it if someone can help with some Q&A please...

1) I've read somewhere that you shouldn't really use more than 20% of a battery's capacity else it buggers up the expected life of the batteries. Is that expected 6yrs if you use the battery in this very conservative manner or is it when you use a lot more of its capacity?

It seems like a bit of a trade-off for me with the batteries. If you use a lot of the capacity, you get away with a few (very expensive) batteries for a short period. If you use only a little of their capacity at a time, you need a whole lot of batteries - 3-4 times more I surmise.

2) Wrt the pure sine wave inverter - looks a really neat piece of kit. From the web write-up, I understand it will basically do the following:
- Switch between mains and batteries depending on if the mains is on
- Charge the batteries
- Act as a 220V inverter

3) Will it be able to warn you if your batteries are running low?
4) Will the inverter still be useful if one add PV in the mix?

5) Also, the whole VA and kW thing is confusing. I saw a few things where the VA rating is higher than the kW rating. Can you explain why that is?
It's only hifi people....

Offline chrisc

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Re: Cutting through the BS for alternative power
« Reply #19 on: February 10, 2015, 10:20:31 PM »
You must bear in mind what is required to convert a DC voltage to 220 VAC

One simple way to do it, is to convert the DC to AC and use a transformer to increase this to 220 VAC

Lets assume you want to power mains devices up to a nominal 500 watts

Starting from a 12 volt battery, we would then have 12 VAC.  It is necessary to multiply this by 18 times to get 220 VAC.  500 watts at 12 volts = 42 amps.  At this kind of current, the windings of the transformer are going to get very hot and a lot of energy will be wasted generating this heat.  You will see that the specs of 12 volt inverters seldom get better than 75%

If you can get a 48 volt inverter (which should cost the same) then you only need to multiply the 48 VAC by 4.6 times and 500 watts at 48 volts is (only) 10.4 amps, so the transformer is much smaller.  Efficiency can reach 93% which is about as good as you are going to get

To get 48 VDC is easy - connect 4 x 12 volt batteries in series.  Since a 12 volt battery consists of 6 x 2 volt cells wired in series anyway, another few sets of cells makes no difference

Regarding the amount to which you should discharge batteries, certain types (particularly lead calcium) can be discharged to about 50% and safely recover.


Another question - watts and VA

Here you need to know the power factor.  This is the ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work.  I know this is a tricky concept, but read this article (which will save me 10 mins typing) http://en.wikipedia.org/wiki/Power_factor

(An incandescent lamp has a power factor of 1, an CFL lamp will have a power factor of 0.5)

Apply the following formula

How to convert apparent power in volt-amps (VA) to real power in watts (W).

The real power P in watts (W) is equal to the apparent power S in volt-amps (VA), times the power factor PF:
P(W) =  S(VA) × PF
So watts are equal to volt-amps times the power factor.
watts = volt-amps × PF
or
W = VA × PF
Example
What is the real power in watts when the apparent power is 3000 VA and the power factor is 0.8?
Solution:
P = 3000VA × 0.8 = 2400W

Offline Atjan

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Re: Cutting through the BS for alternative power
« Reply #20 on: February 10, 2015, 10:53:15 PM »
/\  :clap:
Thanks for the clarification Chris, much appreciated.
It's only hifi people....

Online Kemosabe

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Re: Cutting through the BS for alternative power
« Reply #21 on: February 11, 2015, 12:55:22 AM »
Brilliant explanations Chris.
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Offline philipc

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Re: Cutting through the BS for alternative power
« Reply #22 on: February 16, 2015, 01:35:22 PM »
Chris....want a job at Eskom? I am sure they need you there asap!
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Offline Trompie67

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Re: Cutting through the BS for alternative power
« Reply #23 on: February 16, 2015, 04:03:33 PM »
Chris....want a job at Eskom? I am sure they need you there asap!

The scary part is my Mother in Law has a couple that are close friends, as such we see them intermittently at her place. The husband is 81 years old & is currently contracted via a 3rd party to Eksdom (and has been for the last 6 years) & is on the Medupi build. His contract was renewed in December for another 3 years - he will be 84 when his current contract expires & he is guaranteed (unofficially of course) a further 3 years as he will be moved across to Kusile. it's bloody hard work for him commuting to Medupi weekly for 3 days at a stretch, he is no youngster & is taking strain. That said he has knowledge & experience that is invaluable to the project. Pity Eksdom retrenched him ("early retirement") 14 odd years ago.......
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Offline chrisc

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Re: Cutting through the BS for alternative power
« Reply #24 on: February 16, 2015, 05:33:32 PM »
Chris....want a job at Eskom? I am sure they need you there asap!

Very last place I'd go.  Besides that, I'm not black enough, in fact I'm not black at all

Offline Family_Dog

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Re: Cutting through the BS for alternative power
« Reply #25 on: February 16, 2015, 07:41:55 PM »
You could become a coal miner, you would soon lose the paleness  ;)


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Offline philipc

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Re: Cutting through the BS for alternative power
« Reply #26 on: February 17, 2015, 09:34:09 AM »
Joking aside, there are actually some decent blokes still working there, trying their best, but they are not the decision makers and they are a little 'demotivated' to put it lightly.
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Offline LeonardF

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Re: Cutting through the BS for alternative power
« Reply #27 on: February 18, 2015, 11:48:40 PM »
Mantech have a range of inverters, cost is about 20% less than the suppliers above

An electronics shop in China Town sells inverters.  I am going along there tomorrow with this friend and some measuring instruments to see if they are within spec
How did your China Town trip go. Was there anything worthwhile?

I notice some of the inverters out there come with built in AC charger, although one does need to be careful as some: namely the Meanwell TN-1500 only delivers 5.5A on the 12V unit.
http://www.rectifier.co.za/Meanwell/dcac_true.html
The unit does have PV capability with a PV charger as well and software to switch between the two. The problem here is at 5.5A charging say 2 x 100Ah 12 V batteries in parallel, it is going to take 40 hours or so to charge
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Offline Andrew

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Re: Cutting through the BS for alternative power
« Reply #28 on: February 26, 2015, 03:50:40 PM »
More on the side of solar power - a friend of mine has ring-fenced her house with solar lights, so that if power goes off at night she at least still has a bit of illumination around the house. I took a closer look at them this past weekend and didn't want to say anything to her, but the build quality is shocking and she says that although they advertised the lights would last for around 7 hours, it's actually closer to about three or four hours before they run out of power. Has anyone used similar devices and what were your experiences? Are there decent ones out there at respectable prices, or is the market a mixture of silly expensive on one side, and cheap Chinese imitation plastic that will fall apart after two or three months on the other?
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Offline Trompie67

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Re: Cutting through the BS for alternative power
« Reply #29 on: February 26, 2015, 04:01:00 PM »
More on the side of solar power - a friend of mine has ring-fenced her house with solar lights, so that if power goes off at night she at least still has a bit of illumination around the house. I took a closer look at them this past weekend and didn't want to say anything to her, but the build quality is shocking and she says that although they advertised the lights would last for around 7 hours, it's actually closer to about three or four hours before they run out of power. Has anyone used similar devices and what were your experiences? Are there decent ones out there at respectable prices, or is the market a mixture of silly expensive on one side, and cheap Chinese imitation plastic that will fall apart after two or three months on the other?

We bought some cheapies from Makro to light the garden - little garden lights that have a small solar panel on the top.

They last from sundown until around 04h00 - before we installed the generator we would bring them inside & use as lighting - not very bright, but put 2 of them in a vase on the bedside table & you can read by them no problem at all.

They have lasted just over a year - we got them December 2013!

Link: http://www.makro.co.za/home-and-catering/nature-worx-10-pack-stainless-steel-solar-light-253233EA

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