‘Reserving judgement’: Perceptions of pumped hydro and utility-scale batteries for electricity storage and reserve generation in New Zealand

Renewable electricity expansion highlights the need for a review of energy storage options. Wind power growth, in particular, is likely to require the support of dedicated fast-start reserve capacity. Moreover, in New Zealand, non-pumped hydroelectricity-based storage has only limited potential to meet seasonal variations of hydro inflows. This constraint has contributed to several ‘dry-year’ events over the last decade. This case study surveys New Zealand electricity sector experts as to the feasibility of meeting reserve capacity needs while reducing carbon emissions through the introduction of pumped hydro and utility-scale batteries by 2025. Most respondents project peak power demand to continue to increase, resulting in new-build centralised (∼150 MW) thermal reserve power sources. Pumped hydro is seen by most as prohibitively costly, but is almost universally viewed as technically capable of providing renewables support and peak power adequacy. Utility-scale batteries are seen as least cost-effective, with very high storage costs per kWh and most likely only to be used in NZ for very high-value applications where there is a strong technical advantage, such as the six-second instantaneous reserve. A price of carbon of around NZ$100/tCO2-e, however, was seen as making these technologies much more competitive, and climate change mitigation was seen as a strong driver of these storage options.