Electricity grids need to grow bigger

Electricity is way to go to move beyond fossil fuels and check how low it is presently of the total so they will be expanded and increased substantially to make it a bigger share.
So the (thumb suck) predictions are as follows:


Got some better alternatives?

Your sentence is unintelligible.

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How about: To transfer the power that we generate we will need to utilize electrical grids on a much larger scale than we do presently to achieve the required emissions targets by 2050.


@Phil.g00 Looking at your pic I have wondered why you’re behind bars. Is it perhaps that they have canceled your retirement until that big expansion job is complete??

I’ve been behind many a bar in my time. Retirement is about 18 months away (hopefully).
I postponed it because I intend to live longer than I could afford to.

Further to this topic here is a podcast on the UK grid: (It also discusses DC :slight_smile:)

There’s a free trial period so use that to gain access

From what I gather from Gerhard Salge of Hitachi Energy the move to the new grid will involve HVDC supplies. These are used to introduce reactive power into existing grids for their their ‘grid forming’ role.
My guess is this is why there is so much more electrical power flowing in the new grids.
The estimate is 3 times what is currently flowing. (but it might not mean the grid will be supplying 3 times as much power??)

As with everything, there are tradeoffs.
EHV AC transmission lines have losses proportional to the current magnitude, hence the quest for higher and higher transmission voltages.
But AC power transmission at 50 Hz also translates into around a 6000km wavelength.
Power transmission becomes unstable if it exceeds a 90-degree phase shift, which is around a quarter of 6000km. This is the reason there are series cap banks on the transmission lines down to the Cape. The phase shift effect of a capacitor makes it appear as if the transmission line is shorter than it actually is geographically.

HVDC does not have this problem and is only subject to resistive losses, making it more efficient. But it needs costly end equipment to make the AC/DC and DC/AC conversions.
Anecdotally, in my limited dealings, the end equipment seems to have a relatively high downtime for maintenance issues compared to AC.

But, the real disadvantage in my mind is that DC transmission does not convey any system momentum whatsoever. An AC powerline at 50Hz represents all the mechanical momentum of all the spinning rotors on the system. To budge that frequency, every generator on the system has to speed up or slow down. That is not easy to do, which is why conventional power systems are inherently stable. (This is when the generation matches the load, hence the bouts of load-shedding).

In a conventional AC grid, the power transfer is backed up by a proportional amount of spinning mechanical mass. DC transmission line end equipment is an artificial AC created electronically and doesn’t contribute to system stability. (This would add another dimension of complexity in terms of ensuring system stability during load-shedding).

AC and DC have their place in the transmission system as a blend, but their limitations and applications should be understood.


And this is also why the Western Cape cannot just add as much solar as they want. We don’t have enough spinny stuff this side to do that, all the spinny stuff is on the other end of really long transmission lines. Well, almost all of it.


Yes, there is more to things than taking a fixed stance on coal vs RE, or AC vs DC, cable vs OHL etc.
Oh, the joy of being so ignorant you can be woke.

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They talk about this in the podcast. An interim plan is to add a massive generator with equally massive flywheel similar to what some large installations use for backup power (banks etc.)
But this is simply to add inertia to the grid so it doesn’t use or generate power.


Indeed, there are ways to add mechanical inertia without spinning it with coal or Diesel :slight_smile: But we’re stuck with an AC grid if we do that.

Sometimes it feels like we’re repeating the history from Edison/Tesla times. Although, the story is always hopelessly oversimplified and the real story was the invention of three phase plus the induction motor. Again… spinny stuff :slight_smile:

It’s called a synchronous condenser. It is just a synchronous generator/motor that runs between a motor and a generator.
That said, it does use power, obviously, to cover losses. It also needs a whacking great induction motor to bring it up to near synchronous speed so it is close enough to synchronize with the system.
RE can then power these and in turn, bring stability to the system.

Here’s our new shiny one:


So, get on to CoCT mayor, and get him to buy up some of these smaller generators that ESKOM are decommissioning in those Camdens and Komatis etc. Get them shipped down the Cape and you’ll get your spinny things for cheap.
Then you can have your solar independence.
Cos’ that is all they are, just synchronous machines with flywheels.
And you know that they’ll just get cut up for scrap.


Ah, I always enjoy a good Phil-post.

And Phil-quote.


On that topic. I dislike the word “woke”. But I also dislike the fact that it has become a collective word for everything that is felt to be slightly left-leaning. I mean, if you properly venture into MAGA land (there is another collective word for people you may find disagreeable), simply putting solar panels on your roof or looking at an EV makes you “woke”. Which to me is stupid. The spectrum is just so insanely huge, and the term itself is merely a reboot of something we’ve seen too often before. A group of people are claiming to have seen “the light” :slight_smile:

But with all that said, I absolutely agree with Phil that a lot of “social progressives” are sadly deeply deeply ignorant of the mechanics of the situation.

Not that it is limited to that group either. Take the foam-at-the-mouth response from people about the Frankfort saga. Yes, it is an unfortunate turn of events, but way too many people are cock-sure-of-themselves shouting that this is a conspiracy of the highest order, while in reality it is a legitimate engineering challenge and a risk that cannot be disregarded. The shouting, in other words, shows that way too many people have no idea how running a power grid works…


@Phil.g00 Please clarify why the new grids have 3x more power flowing in them?
Is it because of electricity replacing all the ICE generators and EV charging stations or is it as I suggested reactive power that now is required to stabilise the new grid that has no inertia??

I am sorry, I don’t do those free trials, for the first-month things, so I didn’t read up to that point.
I don’t know the context of the statement.
It might simply be that 3x the power has to flow per conductor in a DC system as opposed to when it is spread over 3-phase conductors.