2021 Investor Day Presentation slide image

2021 Investor Day Presentation

Future dry year flexibility scenarios (3) Onslow-Manorburn (simple) pumped storage 585MW of (new or old) Southland load with no flexibility A simple 4,000GWh storage and 1,000MW power station. scheme: 25% losses: 750MW available for hydro management and 250MW for intermittency management Reservoir release rules determined by dynamic needs of the power system, dispatched according to water-value: Mean dry-year pumping load is 650GWh - 'trickle charge' overnight in summer Mean generation / releases are 325GWh. This will increase as Lake Onslow fills. Intermittency management contributes an extra ~125GWh ■ There is a clear seasonal need for generation In extremes, up to an extra 1,500GWh of generation is dispatched back into the market # of years Annual Onslow-Manorburn Generation output Southland Stimulation; 750MW generator; trickle-charge pumping; No thermal 100 100% 90% 90 80 70 60 Count 50 — SumProb 40 40 30 20 10 80% 70% 60% 50% 40% 30% 20% 10% 0% <0 0 135 135 - 270- 270 405 405- 540- 675- 810- 945 1,080 1,215 1,350 1,485 1,620 1,755 1,890 - 540 675 810 945 1,080 1,215 1,350 1,485 1,620 1,755 1,890 2,000 annual generation [GWh] sum prob ( years) Source: Meridian The estimated $4B+¹ Onslow scheme can be a viable dry year mechanism, along-side other sources of flexibility ¹estimated cost, not including further required investment in transmission Meridian. 11 MAY 2021 2021 INVESTOR DAY PRESENTATION | 30
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