Invitation to Comment: 2025 Security of Supply Assessment: Reference Case Assumptions and Sensitivities (Closed)

Submissions closed 9 December 2024

Transpower, as the system operator, is responsible for annually publishing the medium-term security of supply assessment (SOSA). This assessment provides a ten-year view (2025 to 2034) of the balance between supply and demand in the New Zealand electricity system.

Three security of supply margins will be evaluated, the:

1. New Zealand Winter Energy Margin (NZ-WEM);
2. South Island Winter Energy Margin (SI-WEM) and
3. North Island Winter Capacity Margin (NI-WCM)

For the 2025 SOSA, we will continue to utilise a single reference case and sensitivities as the method of presentation. The reference case does not represent the most likely outcome. Its assumptions are based on public information, and confidential surveys. These assumptions represent the resources available to the power system over the next ten years. It should be interpreted as what the market could develop, not necessarily will develop.

Sensitivities (and plausible combinations of sensitivities) from the reference case will be assessed by flexing different variables. This will allow stakeholders to better assess the key variables that can impact the energy and capacity margins under different potential future states.

The purpose of this document is to invite feedback from market participants on two areas of the 2025 SOSA prior to drafting:

• the proposed key reference case assumptions, and
• the sensitivities that we are proposing to apply (individually and combined) to the reference case.

Submissions

We received 4 submissions listed below.