Carbon Forecast: Wednesday 16 September 2026

South Australia and Tasmania are running the cleanest grids in the NEM this morning, with intensity at 0.107 tCO2/MWh (80.9% renewables) and 0.014 tCO2/MWh (97.9% renewables) respectively. Tasmania's hydro fleet is supplying 1,162 MW against wind of 208 MW, keeping the region at or near zero intensity for most of the overnight period. SA's 1,119 MW of wind generation dominates its mix, with gas (CCGT and OCGT combined at 288 MW) filling the balance. At the other end, Victoria sits at 0.861 tCO2/MWh with renewable penetration down to 24.8%, as brown coal (3,810 MW) continues to carry the bulk of load with wind contributing 628 MW and solar negligible at this hour. NSW (0.625 tCO2/MWh, 29.0% renewables) and Queensland (0.648 tCO2/MWh, 26.1% renewables) sit in between, both leaning on black coal fleets above 5,100 MW.

The generation mix data confirms the pattern driving these numbers: SA and Tasmania have no coal in their stack, so intensity tracks wind and hydro availability almost directly. NSW, VIC, and QLD all carry large coal baseloads (black coal in NSW/QLD, brown coal in VIC) that keep intensity elevated whenever wind and solar output softens, as it typically does in the early evening ramp. Victoria's trajectory over the past 24 hours shows this clearly — intensity climbed from 0.571 tCO2/MWh at midnight to a peak near 0.974 tCO2/MWh around 17:25-18:55 as solar dropped to near zero and renewable share fell to 16%, before easing slightly into the evening.

Looking at today's outlook, expect NSW, VIC, and QLD to follow their typical diurnal pattern: intensity troughs overnight and in the early morning hours (00:00-05:00 AEST) when wind output is strongest relative to demand, then rises sharply through the morning ramp as solar hasn't yet reached peak and demand builds. The cleanest window for carbon-sensitive loads in the mainland regions is likely between 00:00 and 04:00 AEST, where NSW has historically dropped to around 0.34-0.35 tCO2/MWh and QLD to around 0.41-0.46 tCO2/MWh on renewable shares above 55%. Midday solar should pull intensity down again in NSW and QLD, but VIC's midday intensity has been rising instead, given its heavier reliance on wind versus solar. SA and Tasmania will remain the lowest-intensity options across nearly all hours today, with SA occasionally dipping toward 0.03-0.08 tCO2/MWh whenever wind output strengthens overnight and Tasmania sitting at or near zero for most of the day on hydro dispatch.