Wind generation has once again been making headlines over the past few weeks, on two different fronts:

1. From the outside looking in, we’ve seen several stories in the mainstream media regarding the public opposition facing several proposed wind projects. Notably, seen through a Four Corners episode titled ‘The Wind Wars’ two weeks ago. In a similar vein, a widely-read article in the Conversation, penned by several academics, raised concerns over the biodiversity impacts of several proposed wind farms in Queensland.
2. From the inside looking out, the NEM’s existing wind fleet has been grappling with a rather consequential ‘wind drought’ since April. It has been tracked closely here on WattClarity, with additional coverage by the AFR and RenewEconomy.

The two issues are unrelated in the short-term, but are important to consider in tandem in the long-term, especially in light of the AEMO’s Integrated System Plan (2024 ISP) released earlier today.

A closer inspection of Q2’s wind yield may offer a real-world glimpse into the challenges facing our current electricity system, mid-transition.

Where we are

Throughout Q2, we’ve observed several instances of supply-demand tightness in the electricity market. Several factors have been at play, including multiple prolonged wind lulls. Compared to recent years, we’ve additionally seen cold temperatures driving increased heating demand, relatively low production from hydro, and increased production from coal. The latter two factors are likely to have resulted in an increase in net emissions when compared to previous second quarters. Our annual analysis of Q2 prices in coming weeks will examine economic outcomes.

The gas system has also faced a squeeze, culminating with the AEMO issuing a ‘Risk/Threat Notice’ for the east-cost gas system last week. Again, there have been several factors at play – with others such as David Close having published more nuanced thoughts on the structural issues in both gas production and storage (i.e. beyond GPG). There are caveats in linking the current situation in each market, as Paul listed here.

Storage levels at Iona Underground Gas Facility are still on the decline (seen since mid-May).

Source: AEMO

How we got here

Taking inspiration from Paul’s ‘worm’ charts – in the video below I’ve animated a rolling 3-day cumulative trend of total production, and have also added spatial data to track production by location (also shown on a 3-day rolling cumulative basis).

There are two reasons why I’ve chosen to analyse the data in this manner:

1. to highlight the fluctuating nature of yield from the NEM’s wind fleet as it is currently composed, but also;
2. to underscore the challenges in satisfying volume, spatial, and ramping requirements – for gas and/or long-duration storage – in a future grid that will eventually depend on VRE to function. A challenge that is hard to imagine will be solved by the current fleet of ‘big batteries’, which all have a duration of ~2 hours or less.

A view of the 3-day rolling cumulative wind generation trend shows four distinct wind lulls over a span of 2.5 months.

Data source: NEMreview

The animation attempts to show two different dimensions of data at the same time (i.e. space and time), so I’d recommend that viewers make use of the pause button to better understand both dimensions at each point.

There are many moving parts in a system-wide view, but I’ve attempted to annotate four distinct wind shortages over Q2 (where the rolling total dipped below a 15% capacity factor for consecutive days), with approximate dates:

• Wind Lull #1 (13th April to 20th April): Underperformance of wind farms in VIC, NSW, and parts of SA.
• Wind Lull #2 (13th May to 18th May): Underperformance of wind farms in SA and VIC.
• Wind Lull #3 (22nd May to 28th May): Underperformance of wind farms in VIC, SA, NSW, and parts of TAS.
• Wind Lull #4 (5th June to 11th June): Underperformance of wind farms in QLD, SA, and TAS.

The occurrence of successive wind lulls, reinforces the conclusions published in a WattClairty piece two years ago by Geoff Bongers, Nathan Bongers and Andy Boston – how seasons of low wind and solar will influence what system we need to design for.

As a form of reference, the capacity factors for all semi-scheduled wind farms for last year (although on a monthly basis) are shown in the chart below for comparison. This chart was included in our presentation to the Clean Energy Council back in May.

For comparison, volume-weighted capacity factors in 2023 were markedly higher in April (25.81%), May (29%) and June (41.2%), compared to what we just saw in Q2 2024.

Source: GSD2023

I’ll also note that the first animation only covers production (i.e. output) and not availability (a better reflection of available wind resource). Transmission outages and other network constraints have also been impacting wind production, particularly in NSW, perhaps most notably on May 8th – although that individual occasion did not coincide with the wind lulls mentioned above. Paul has covered other reasons why wind output may have been suppressed in a longer article posted last Saturday.

Key Takeaways

• We’re still at a point in the transition where we should prepare for the ‘dunkel’ and the ‘flaute’ separately. ‘Dunkelflaute’ is a german phrase now synonymous with periods of low solar and wind production – with the literal meaning loosely translating to ‘dark’ (Dunkel) ‘lull’ (Flaute). Whilst there are significant challenges when both happen simultaneously, Q2 has shown us that each separately can be just as consequential.
• Wind resource diversity has system-wide value. However, as we’ve written about ad nauseam – don’t mistake this for saying that this diversity will solve all of the challenges.