Can Planned Renewable Development Mitigate Near-Term Dry-Year Electricity Risk in Aotearoa New Zealand?

Dry-year electricity shortfalls are a defining energy security challenge in Aotearoa New Zealand. Low hydro inflows and ongoing hydro releases deplete seasonal energy storage, increasing reliance on thermal generation, particularly during winter. Amid declining domestic gas reserves and tightening climate commitments, debate persists over how best to maintain system reliability. Our viewpoint provides quantitative modelling evidence, using the open-source PyPSA-NZ framework, on whether renewable energy projects in late stages of development can provide reliable electricity during a dry year within the next 5 years. These projects would add 3200 MW of solar photovoltaics, 500 MW of wind power, 130 MW of firm geothermal and 1050 MW of battery storage providing short-duration flexibility. Because solar and wind are dispatched ahead of hydro, this capacity would displace hydro generation year-round and raise reservoir storage entering winter. Reliability is secured primarily by this additional stored energy. Using the 2012 hydrological dry year as a stress test, we show that, if these projects are delivered, the modelled system maintains reliable supply without further investment in firm capacity or fuel supply. This suggests the main near-term risk to electricity reliability is not a shortfall of generation, but constraints on integrating new renewables, including transmission capacity and financing. We propose that near-term energy security policy prioritises the timely delivery of planned renewable energy projects.