Carbon Forecast: Tuesday 18 August 2026

South Australia carries the lowest carbon intensity in the NEM this morning at 0.0323 tCO2/MWh, with renewables at 93.42% of generation — wind alone is supplying 1,159 MW against negligible gas-fired output of just 0.11 MW OCGT and 82.7 MW CCGT. Tasmania sits second-lowest at 0.0943 tCO2/MWh with 85.49% renewable penetration, hydro contributing 382 MW alongside 342 MW of wind. Queensland carries the highest intensity at 0.6723 tCO2/MWh with renewable share down at 23.22%, reflecting 5,331 MW of black coal generation against 1,329 MW of wind and minimal solar output of just 3.4 MW at this hour. NSW follows closely at 0.6391 tCO2/MWh (27.29% renewable) with black coal at 5,576 MW dominating the mix, while Victoria reads a comparatively moderate 0.581 tCO2/MWh with renewable penetration at 52.38%, wind output of 3,590 MW offsetting 3,400 MW of brown coal.

The trajectory across mainland regions through today's session tracks the solar and wind resource. NSW and QLD both show overnight troughs in intensity around 0.43-0.45 tCO2/MWh in the early hours before rising sharply through the morning ramp as solar output falls away and demand builds, peaking near midday to early afternoon at 0.70-0.71 tCO2/MWh in NSW and similar levels in QLD, before easing modestly into the evening. Victoria shows a more favourable midday profile, dropping to 0.517 tCO2/MWh around 13:25 as wind generation strengthens, sustaining relatively low intensity through the afternoon before climbing again into the evening peak. SA's carbon intensity stays in negligible territory for most of the day, dipping to its floor of around 0.0099-0.0102 tCO2/MWh mid-morning through early afternoon when wind generation is strongest, before renewable share tapers off into the evening as intensity climbs toward 0.03 tCO2/MWh.

For carbon-sensitive loads seeking green windows today, SA remains the standout option nearly continuously, with its lowest-intensity window concentrated between 08:30 and 14:00 AEST when intensity sits below 0.011 tCO2/MWh and renewable penetration exceeds 97.8%. Tasmania's best window falls in the early morning between 07:00 and 09:30 AEST, when intensity drops to 0.055-0.056 tCO2/MWh on strong hydro-wind combination. Victoria's optimal window for load-shifting sits in the early-to-mid afternoon, roughly 13:00-14:30 AEST, when intensity troughs near 0.517-0.519 tCO2/MWh. NSW and QLD offer comparatively narrow low-carbon windows overnight into early morning (before 04:00-04:30 AEST) and should be treated as higher-intensity regions for the bulk of today's operating hours, with midday-to-mid-afternoon representing their highest-emission period as coal generation dominates and solar contribution remains modest.