The green energy transition towards net zero depends on massive amounts of storage to cover the gaps in the generation of wind and solar power, especially on windless nights.
The underlying concept behind the Snowy 2.0 Pumped Hydro Energy Storage (PHES) Scheme is to generate electricity by releasing water from the upper Tantangara reservoir to drive the turbines and to capture the released water in the lower Talbingo reservoir. During periods of excess electrical energy in the National Electricity Market (NEM), the water is pumped from Talbingo back to Tantangara, thus completing a cycle.
The Tantangara reservoir has an active storage of 240 GL which, theoretically when full, is sufficient to generate 350 GWh of electrical energy (2000 MW for 175 hours) as promoted by Snowy Hydro.
Tantangara Reservoir has never been more than 70% full in the 23 years to December 2020. This means that there has never been sufficient water to generate the specified 350 GWh of electrical energy over 175 hours.
In addition, the long-term average weekly volume of the Tantangara reservoir, in the same 23 years, is 18.15% which allows only 32 GL to be used for generation.
The long-term average storage available in Talbingo is approximately 33 GL. This volume is clearly insufficient to support 175 hours of generation, unless the water is allowed to spill which may violate the conditions of the ‘Snowy Water Licence”
The sorry story
The scheme was announced by PM Turnbull in 2017 with an estimated cost of about $2bn. The feasibility study in 2017 predicted a cost in the range of $3.8bn to $4.5bn and the scheme was expected to deliver power by late 2024.
Nowadays it is uncertain whether the scheme will ever be completed and cost estimates (including major transmission lines and a substantial wind fleet) run over $20 billion. The scheme depends on pumping power from a fleet of wind turbines that is almost as large as the currently installed capacity of wind power in the NEM. These additional facilities will cost in the order of $14bn, not counting the transmission lines.
Snowy Hydro’s own modelling anticipates annual generation in the order of 2.8 Terawatt hours. The review of the project by Bowden and Brooking has determined that for a cost of $8bn, the average sale price for the energy generated in the 50-year life of the scheme needs to be in the order of $450/MWh. This is greatly in excess of the $135/MWh predicted in the business case.
The scheme depends on pumping power from a fleet of wind turbines that is almost as large as the currently installed capacity of wind power in the NEM. These additional environmentally destructive wind facilities will cost in the order of $14bn, not counting the transmission lines.
The scheme does not deliver a continuous flow of power because there is a pumping phase when water is moved from the lower reservoir to the upper level and a generation phase when the water runs down through the turbines. During the generation phase, a flow of 2000MW is specified. Whilst unrealistic, this is the scale of a large coal-fired power station; however, because the flow is not continuous, the total output is significantly less than the output from a conventional power station.
This means that the wind turbines and the Snowy 2.0 pumped hydro facility combined do not replace a single 2000MW (2GW) of coal power.
To replace the 20+ GW of coal capacity in the NEM, a substantial number of schemes on the scale of Snowy 2.0 will be required. The prohibitive cost of pumped hydro to support individual wind farms was calculated in a briefing note circulated to all state and federal MPs in April 2021.
It should be noted that no significant pumped hydro scheme in the world runs on wind and solar power alone. The largest facility at Bath, Philadelphia (US) runs entirely on coal and nuclear power to enable those plants to run continuously at their optimum output.
That politicians take note of the limited capacity of pumped hydro.
That journalist and commentators convey the facts about storage cost and capacity to the public.
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