Carbon Forecast: Sunday 21 June 2026

Victoria carries the highest carbon intensity on the NEM right now at 1.10 tCO2/MWh (06:30 AEST), with renewables at just 3.25% of its mix — brown coal at 4,303 MW and gas OCGT at 753 MW account for the bulk of its generation. Queensland sits at 0.71 tCO2/MWh with 16.23% renewables, driven by 5,181 MW of black coal and 786 MW of gas OCGT, with battery (641 MW) and wind (396 MW) providing the remainder. NSW is at 0.70 tCO2/MWh on 17.04% renewables — 6,907 MW of black coal dominates, supplemented by 1,328 MW of hydro and 558 MW of gas OCGT. South Australia sits at 0.53 tCO2/MWh with 9.51% renewables; gas (OCGT 849 MW plus CCGT 605 MW) makes up nearly all generation, with wind at just 44 MW at present. Tasmania registers 0.00 tCO2/MWh at 100% renewables, running entirely on hydro (1,369 MW) and minor wind (19 MW).

The day's intensity trajectory is clear from the overnight data. Across NSW, QLD, and SA, intensity fell through the early-morning hours as thermal generation eased, reaching intraday lows between roughly 13:30–14:30 AEST (03:30–04:30 UTC). NSW touched 0.54 tCO2/MWh and SA reached as low as 0.25 tCO2/MWh in those windows, coinciding with peak overnight wind penetration. Intensity then climbed sharply through the morning peak as thermal units ramped back up and solar contribution remained minimal in this winter period — NSW is now 0.17 tCO2/MWh above its overnight low, and VIC has risen more than 0.17 tCO2/MWh from its overnight trough to reach today's high above 1.10 tCO2/MWh. Victoria's intensity has remained persistently elevated throughout the day with renewables consistently below 15% and wind nearly absent at 13 MW.

For carbon-sensitive scheduling, today's lowest-intensity windows have already passed for most mainland regions — the 01:00–05:00 AEST band delivered the best conditions. Looking ahead through the rest of today (06:30 AEST onward), no solar uplift of consequence is expected given winter solar angles, and the intensity profile is unlikely to improve materially until overnight wind ramps again after approximately 22:00–23:00 AEST. SA is the most responsive region to watch: its intensity can shift 0.20–0.30 tCO2/MWh within a single hour when wind picks up, as seen in the 08:55–09:55 AEST window overnight where renewables briefly exceeded 56%. Loads in TAS1 face no carbon constraint at current generation conditions. Operators with flexibility to shift consumption to the post-22:00 AEST window across NSW and SA will capture the next meaningful low-intensity period.