In last week’s article, Did solar and wind wilt in the heat, I sought to illustrate that the output of wind and solar power over the Victorian and South Australian heatwave week beginning January 13 was consistent with what the Australian Energy Market Operator (AEMO) expects and plans for in trying to ensure reliable supply of electricity.
This was in an attempt to address alarmist claims that what occurred over the heatwave suggested that the Renewable Energy Target placed power supplies at high risk of blackouts.
But I made a mistake, misinterpreting a chart I was sent from Infigen Energy which illustrated the accuracy of AEMO’s wind energy forecasting system during the heatwave.
I’d originally thought the chart showed the systems’s forecast for 24 hours ahead, but it turned out to, in fact, be for only an hour ahead. This was subsequently seized upon by tabloid columnist Terry McCrann as part of an article criticising me as a “dishonest”, “warmist propagandist”.
I’ve criticised McCrann a few times for errors myself so it’s only fair to expect some criticism back. After all, I’ve told him he might benefit from familiarising himself with the Bureau of Statistics economic input-output tables before predicting an economic Armageddon from the carbon tax.
And I’ve also noted that in mocking the low power output of AGL’s Macarthur Wind Farm during 2012 McCrann might have been a touch unfair given the wind farm was still undergoing construction at the time.
In this recent article McCrann observed:
“On his website he [Tristan Edis] wrote that AEMO had an 'ace up its sleeve' – being able to accurately forecast the amount of wind power that would be generated 24-hours in advance. He charted the forecasts against the actual output and showed a remarkable – indeed impressive – co-relation ... It didn't help his case that his article carried a correction that the accurate forecasting wasn't 24 hours ahead but just a single hour. What a way to run a grid – checking whether the wind is blowing and then 'forecasting' it will continue to for the next hour.”
So, for our chart of the week and to expose my dishonesty about the market receiving plenty of advance notice about any drop-off in wind farm output over the heatwave period, I’ve tracked down the data on AEMO’s wind energy system’s forecasts for 24 hours ahead over the period of the heatwave.
The chart below, prepared by AEMO, shows its system’s forecasts for wind farm output in SA for 24 hours ahead (green line) and 12 hours ahead (red line) compared to actual wind farm power output (blue line). As you can see the system accurately forewarned other market generators of the significant drop-offs in wind farm output that occurred over this week.
Source: Australian Energy Market Operator
So is 24 hours a good amount of warning time in operating the grid?
On this point it is useful to refer to tables that AEMO publishes on how much each generator’s output can be ramped up or down within an hour and the minimum level of output these plants can go down to and remain stable. These show that power generators across the NEM, including many brown coal generators, are capable of ramping their output up and down by a considerable amount within one hour, let alone 24 hours.
In spite of all this I should acknowledge an accurate point McCrann makes in his article. Wind power’s installed capacity (even when geographically dispersed) can only be relied upon to a small extent to be available during peak demand periods. While both wind and solar PV do a good job of reducing the frequency with which we use fossil fuel power plants (and therefore their greenhouse gas emissions) you wouldn't want to rely on these technologies alone for displacing the available capacity you can draw upon from a fossil fuel power plant.
This has actually been well demonstrated using real-weather data in model simulations by University of NSW researcher Ben Elliston and also by the Australian Energy Market Operator’s 100 per cent renewables study.
But I wasn’t disputing that fact. What I was disputing were claims that the heatwave period demonstrated that the Renewable Energy Target was going to substantially increase the risk of blackouts. This reasoning is seriously flawed.