The Murray Darling Basin Authority and Meridian Energy Australia have begun a new trial aimed at avoiding summer price spikes and blackouts by targeting water releases from Hume Dam at times when solar power is waning and grid demand surging.
If the trial succeeds, the practice of managing water releases to better stabilise the grid could be applied to other dams and become a more powerful tool for integrating wind and solar energy into the grid, Meridian chief executive Ed McManus said.
"By releasing more water at times of the day with peak electricity demand we will make better use of the Hume Dam to generate electricity when it is most needed, with no impact to downstream water users," Mr McManus said. "More electricity supply at peak times has the potential to lower wholesale prices."
Meridian, which operates wind farms in South Australia and Victoria, bought hydro power stations on the Hume, Burrinjuck and Keepit dams this year to ensure more reliable, low-carbon supply for its Powershop retail arm. Lake Hume, on the Upper Murray, is the largest with 3005 gigalitres capacity but is now just under half-filled.
Some dams, such as the big Dartmouth Dam on the Mitta Mitta River in Victoria, operated by AGL Energy, and the vast Snowy Hydro scheme in NSW, already have a lot of flexibility in when they release water thanks to multiple storages, but "run of river" dams – including Meridian's Burrinjuck and Keepit dams – could benefit from the trial.
Armoury of grid weapons
The trial will take about six months. To ensure irrigators, communities and environmental flows are protected the variations will have to be kept within existing operating parameters, Murray Darling Basin Authority (MDBA) head of river management Andrew Reynolds said.
Optimising the role of hydro to make it work harder to stabilise the grid at times of tight supply could add to the armoury of weapons – including home and grid scale batteries, gas peaking plants and "demand response" – at the disposal of grid operators and suppliers.
The need for more powerful tools to manage the grid is taking on greater importance as more and more wind and solar energy comes into the grid, straining a legacy system of poles, wires and substations built for a simpler, centralised power system.
Mr McManus said that in the height of summer the dam would likely be releasing the maximum amount of water anyway. But any time it was releasing less than the maximum there would be potential to about double the output from the hydro dams at peak demand times.
"We'll release less overnight and ramp up during the day to coincide with the late afternoon and early evening, which is when we see peak demand," Mr McManus said.
Closing the supply gap
He said that when the Australian Energy Market Operator signals a gap in supply at times when demand for electricity is surging, it is typically for small amounts such as 100 or 200 megawatts.
"If we can have a little bit more from hydro and have some demand response you'd be going a long way to closing that gap," Mr McManus said.
Under demand response, solar panels, batteries and smart appliances such as pool pumps, aircon and industrial fridges located "behind the meter" in people's homes and businesses can be marshalled to support the grid at peak demand times.
Mr Reynolds said the trial aims to deliver "business as usual" benefits to existing stakeholders – irrigators, communities and the environment – while improving electricity generation and providing extra network support over summer.
"While river levels will vary most noticeably immediately below Hume Dam, they will remain within the current range of variability and will dissipate by the time the flow reaches Albury. With current conditions being so dry it's important to note the trial will not impact on water availability for entitlement holders downstream of Hume."
He said the trial would start conservatively with a regular scheduled release pattern that varies water releases at Hume Dam from 2pm to 8pm on weekdays. Releases will be closely monitored throughout the summer to ensure there are no adverse impacts on native fish or bank erosion rates.