Ok. Turbines that run on diesel, or even gas, use a lot of fuel. Huge amounts. While they are fantastic in the right application, they are not so good in others.
That's why we have them as peakers rather than baseload. Fast to start, make lots of power for their size however they are very expensive to purchase, run and maintain. Thanks to the peaks and dips of the load of the grid, we need these peaking machines for literally just a few hours a year. Some years they might not run at all, except for testing. However, there is no real alternative. You can't build a baseload power station to run for a couple of hours per year.
There are also quite a few peakers around the are reciprocating gas powered engines although they tend to be much smaller capacity. So, it's horses for courses.
Back to diesel turbines.
Those 30MW ( approx ) turbines would use tons of diesel per day each. I don't want to post a number off the top of my head without confirming what I know for sure. It's been a while since I've been involved with that stuff and I wouldn't want to post a fake number and mislead the forum , unlike some others .
Here's a link to a story at the time. Frydenburg was trying to score some political points at the time when he made the claim about 80,000 litres per hour " to keep the lights on ".
While I can't confirm whether that number is right, depending on the circumstances, it could be close to that number if everything was running flat out. It certainly is in the ballpark. So, that's 80 tonnes of diesel per hour. You can do the numbers on what that adds up to per day.
Clearly that's anywhere near sustainable, sensible or practical.
So, my recalcitrant friend is right in that it takes a fair bit to keep the diesel up to a big turbine. That is exactly why you don't run them for long. It is just too damn expensive. Crazy expensive.
If we look back at the history of the particular turbines in question, we can see their original purpose. SA had some catastrophic events pretty close together. For a variety of reasons their established backup black start system failed. So, in order to fix that the government took the quite expensive but quick option of purchasing these generators. Like all governments under pressure they probably paid to much but considering the ramifications of having a whole state black for a long period, it makes sense to use these turbines. They are really well proven and they will do the job in an emergency no worries at all.
However, once the turbines and several other things around the state were sorted out, people started to question that decision. Mostly driven by politics. Contract costs etc. It is my understanding that the replacement government revamped the deal to save money. Also , many changes have been made around the state to make the grid much more reliable. More renewable assets, better black start arrangements, upgrades to the interconnector, installation of three big batteries, improvement of software for the solar and windfarms and importantly a better rewritten contract arrangement in terms of supply from those assets.
As more of SA's power comes from renewables, the need for more firming arises. Happily , these turbines are ideal for that in the interim. Converting these turbines to run on gas makes them better for that . Cheaper than diesel ( but still expensive ) and quite a bit cleaner.
So, until industrial sized energy storage is built, firming assets such as these turbines will be used more and more as more renewables come into the grid. How long that will be is anyone's guess.
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