I have been commentating on electricity in my home state of South Australia for the past five years. So it may have surprised some that when the entire state (Yes, the whole place. Everything) went black a little over a week ago that I did not get right out there with comment.
There are two simple reasons for this.
Firstly, I was in China. More on that another time.
Secondly, and more importantly (wait for it)… I absolutely did not know or understand what had happened.
And, as I gradually took in news report, tweet, meme, media release in my inbox and op-ed, it became pretty obvious that no one else did either. What we have had is a week of furious politicking and spin, across the board, because seemingly no one was prepared to say “I don’t know yet”. It was seemingly more important to get preferred messages embedded in the public consciousness nice and early.
Our state government was quick to claim that this was an extreme weather event resulting from a catastrophic loss of infrastructure and literally nothing to do with our (frankly untested) energy mix. Yep, the wind event was hardcore, the pictures attest to that. Nope, I wasn’t buying the balance of that argument within the first hours because frankly no one knew. A piece from Tony Wood of Grattan Institute seemed to partially reinforce this, plying an argument I am tiring of: “It’s not wind, it’s that our system is not well structured to manage wind”. A lot of South Australians are struggling to appreciate that distinction and never really consented to being placed on the policy vanguard of system reliability in the first place.
Our Prime Minister (Turnbull), State Opposition Leader (Marshall) and independent Senator Xenaphon were quick to pin the blame all on the renewables, seemingly content to ignore a major, weather induced catastrophe that was hurting people in my home town even though at that time they, too, did not know.
The climate hawks had an interesting spin… apparently wind was the hero of the day, chugging away merrily until disaster struck and then swiftly back on deck.
“The fact is the system brought down all three generators for safety reasons after three transmission lines and nine towers fell. And wind generators actually helped restore power- the Snowtown wind farm was the second generator brought online”.
Andrew Stock of the Climate Council
Again, such a claim coming in scarcely after power was even restored is testing credulity because, yet again, they did not know. Independent energy commentator Tristan Edis asked us to compare this to a coal-induced failure in 2005… except that even did not black out the entire state. Fact is we seem to have nothing like this event on the record.
So frankly, the response in this first week has been mostly a politicized, tribal hot air. While I had my ideas and suspicions, I have been waiting for the reports to begin from the Australian Energy Market Operator. The preliminary report was released today and you can read it here.
So what happened? In brief and simple language, South Australia was rolling along merrily and in good shape when warnings of extreme weather came in. About 24 hours later when the extreme whether struck, we were asking for about 1800 MWe of power from our grid, which is connected to the much larger state of Victoria via two interconnectors. About half that power was coming from wind at the time, much of which is based in the north of the state, roughly 20% was coming from gas in South Australia and the balance (30%) was coming through the interconnectors (which is coal, basically).
IMPORTANT ASIDE: The wind generation is providing electrons and NOT frequency control ancillary services (colloquially, inertia) to the system. I discussed ancillary services in a recent post, please read it for more understanding of this. END ASIDE
A section of transmission line south of Port Augusta, near Melrose, was hit with extreme winds, quite possibly tornadoes, and wrecked. Eventually three lines went out of service and six wind farms reduced output. This sudden imbalance of supply/demand was felt as a major drop of frequency. In response, the grid started clamouring for frequency from the rest of the system to stay in operational range (49.5-50.5 Hz). So, virtually instantaneously, it was pulling in supply from other synchronous generators who felt the perturbation in the system, including across the interconnector.
“In the events leading up to SA region Black System, generation reduction occurred at six wind farms. There was no reduction in thermal generation. Each reduction coincided with a drop in voltage observed at the wind farms’ connection points”.
AEMO Preliminary Report
At first it was ok then…more supply gone…more frequency being lost…more clamouring for stability.
ASIDE: Why did the wind farms reduce output? I don’t know. At the moment, neither does AEMO to the extent that they are prepared to publish a finding, but I expect the experts have some ideas.
Additional analysis is required to determine the reasons for the reduction in generation and observed voltage levels before any conclusions can be drawn.
AEMO Preliminary Report
This need for more stability was felt as a demand for 900 MWe through an interconnector designed for 600 MWe. That’s too much. To stop potential for damage, the interconnector cut us off, and it was lights out for South Australia. The chart below from AEMO shows the last few seconds.
ASIDE: Does it matter? Yes, it matters. Folks reflecting on the old days where we had black outs in the suburbs every now and then and dug out the candles are missing something important. That was load shedding where those of us not badly exposed by power loss shared a little pain so others who are exposed kept power. Yes, we dug out the candles with a degree of cheer and then face-palmed when we tried to boil the electric kettle. These hierarchies still exist. Who is badly exposed to power loss? Smelters and foundries: when their product freezes in the wrong place it’s a multi-million dollar problem. Hospitals: they have back-up generators and sure as eggs some failed and people were transferred from intensive care. Food businesses. Street lighting. Traffic lights. These are just a few examples. It’s actually pretty damn important that this does not happen. END ASIDE.
So, what do we know now? Well, the new acronym on everyone’s lips is RoCoF: Rate of Change of Frequency. The system is designed to handle so much and no more and we exceeded it, asking for about 6-7 Hz per second when the maximum is 3 Hz per second. We didn’t have enough generators contributing frequency when we needed it. The chart below shows the frequency response. Note again, the x-axis of time is in seconds. That is the nature of frequency control. We can see that frequency correction occurs within tenths of a second but in the end, it all became too much. So, to reiterate my previous posts, saying that ancillary services are important is not a plot by anyone trying to stomp on renewables that don’t happen to provide them. They are an essential requirement.
Several important questions remain outstanding. Firstly and obviously we will want to know from AEMO their findings about the loss of generation from the wind farms.
The other questions are more nuanced. While the weather event was without question extreme and would always have had consequences, have we perhaps placed our system at greater risk by taking on a greater level of variable, asynchronous generation in form of wind than we were really ready to handle? That’s harder to answer, and asks us to perhaps model the event under different generating mix conditions. For example, we have a relatively clean, modern combined-cycle gas generator in Adelaide (Pelican Point), capable of providing up to 485 MWe that was providing nothing to the market at the time (presumably it was priced out by wind: it has been operating at half-capacity at most since 2013 for this reason). Were this power station serving the market at the time would the events have proceeded differently? We have received recent warnings from AEMO on these changes in our supply and they could not have been much clearer:
If the RoCoF is too high, there is a risk that protection systems sensitive to RoCoF will trip generation in SA. This additional tripping of generation following separation has the potential to increase the impact of the event, increase the amount of load that is shed in SA, and lead to ongoing cascading tripping of generation in SA. As noted above, one of the factors that determines RoCoF in SA is the inertia delivered by the online generating units. Figure 2 shows the inertia in SA since the start of 2012. There is a clear downward trend. This is due to the increase in wind and rooftop PV generation that contribute little in the way of inertia and the consequent removal from service of synchronous generation, which is the major provider of inertia. The total inertia currently available in SA is around 16,200 megawatt-seconds (MWs). 15 In 2017, without Northern Power Station and Torrens Island ‘A’ Power Station, the total available inertia would reduce to around 10,000 MWs.
AEMO, Update to Renewable Energy Integration in South Australia, February 2016
The answer there seems to be “yes”. We have created conditions of greater risk of failure.
Do we need to ensure a greater balance of supply across our grid to spread our risk from transmission losses? Exploiting regional renewable resources like wind (and solar) may seem great, but part of making it cost effective is being as rational as possible with transmission infrastructure. That economic rationality leaves us open to losing hundreds of MWe, perhaps more, from a single point of failure. Ironically, we won’t connect large nuclear plants here for that type of reason.
It’s important to ask and answer questions like this, not to try and put renewables in the frame but to deal honestly with the challenges before us. It may be glib to just “blame” wind and ignore policy and market shortcomings (our failure to price pollution, for example). However I find it equally glib to blame policy and market shortcomings and ignore the inarguable technical shortcomings of wind generation as though we owe it to that sector to provide, and pay for, solutions. For me, that’s a little like the nuclear sector pretending the production of hazardous material is everyone else’s problem, not something to cost into the nuclear electricity. I don’t accept that argument for nuclear and I don’t accept it for wind.
I don’t want to revert to a dirtier grid. In my 2015 paper with Bradshaw and Brook I made it clear that we now have a cleaner grid thanks to wind. But we cannot lose security and reliability along the way in the way we just have. The very real potential for loss of support for our energy journey here in South Australia is palpable right now, with this event coming on the back of record high prices earlier this year.
I argue, based on the preliminary findings now available, that the way forward for clean energy in South Australia must include generation sources that are reliable and can boost the inertia in our system. Ideally we would be able to dot them around our grid to balance generation and mitigate risk from transmission failure. Ideally they would be good load followers to work effectively and economically with the wind generation. Basically, if we want to keep moving to clean while protecting and restoring reliability, we need small modular nuclear reactors.
So, take care before flogging this government. The move to wind has often been very popular here, and whether criticism is deserved or not for current conditions, this government has also shown tremendous courage in bringing the nuclear option to the table for South Australia, and right now they are asking us for our position.
In this commentator’s opinion it is up to us to demand a way forward for clean energy with nuclear involved in our system. If we don’t, we stand a real risk of turning around and going back.
Header image poached from Adelaide Now, who nicked it from ABC. Thank you to informal researchers for content and sources, you know who you are.