Hydro output hits lowest level on Australia’s main grid since market records began

Australia’s main grid, the National Electricity Market, on Sunday recorded its lowest hydro output since records began in 2010.

The new minimum of 172.1 megawatts (MW) came at 1pm (AEST, grid time), on Sunday, and was more than 18 per cent below the previous record minimum reached in August last year.

It came as Tasmania also hit a record low, with a minimum output of just 77.6 megawatts (MW), some 27 per cent below the previous minimum of 106.2 MW in August, 2024.

In Tasmania, a state that is usually dominated by hydro generation, the hydro share of 7.27 per cent reached at the same time beat the previous low of 8.2 per cent, also recording in August last year.

Observations and Considerations:

– Low market prices led to the hydro withdrawal – Regional dispatch prices were low or negative, with Victoria at $31/MWh and Queensland at minus $27/MWh, limiting hydro dispatch incentives.

– Renewables dominated supply at the time, with some 20,386 MW of renewables providing 65.7% of total generation, reducing the need for hydro.

– Battery charging (minus 314 MW) was also soaking up excess renewable energy.

– There was minimal hydro contribution across regions – NSW and Queensland hydro were at very low levels, while Victoria’s hydro was effectively at 0 MW.

This record reinforces hydro’s evolving role from baseload supply to flexible, price-driven operation. As storage and demand-side management grow, hydro may increasingly focus on peak demand support and system stability rather than continuous generation.

A few observations about Tasmania:

– High wind generation and significant Victorian imports displaced hydro – Wind provided 513 MW, while Tasmania imported 429 MW, reducing hydro’s role.

– Tasmania hydro operators may have withheld generation to maintain water storage for future periods of higher demand or lower rainfall.

– There is no utility-scale solar or battery storage in Tasmania yet: Unlike other NEM regions, Tasmania’s low hydro output was not due to large-scale solar or battery charging.

– With Victorian prices lower across the day, Tasmania relied on imports rather than hydro generation.

Meanwhile, at around the same time Victoria set new maximum instantaneous output records for wind (3,983 MW) and combined wind and solar (4,243.0 MW).

Strong wind conditions drove the majority of the increase, and minimal curtailment levels suggests transmission constraints were not a major limiting factor at these peak moments. The high net exports (above 1,400 MW for the wind record) highlight Victoria’s growing role in supporting the broader NEM.