Brooklyn wind turbine in Wellington, New


The NZECS Residual Supply Mix

The NZECS has, as one of its core objectives, the goal of increasing information and understanding around the way electricity is generated in New Zealand. 

To this end, we make sure that generation attributes contained in certificates purchased through the NZECS are not also claimed by non-participating energy users. The mechanism by which we do this is called the Residual Supply Mix, or RSM.

The RSM describes the nature of the electricity for use by reporting energy consumers who do not purchase NZ Energy Certificates directly from generators. It is a key part of how greenhouse gases are accounted for in New Zealand.

The current RSM is described below.

2019/20 Residual Supply Mix

The RSM has been calculated for the period from 1 April 2019 to 31 March 2020. This was the first year in which NZ Energy Certificates were transacted in New Zealand, and so the RSM remains similar to the NSM.

National Supply Mix: the total mix of electricity generation supplying New Zealand's domestic demand.

National Supply Emissions Factor: the emissions factor of the National Supply Mix.

Residual Supply Mix: the mix of electricity generation minus volumes transacted within the NZECS.

Residual supply Emissions Factor: the emissions factor of the Residual Supply Mix.

51,567 certificates were purchased and redeemed in the 2019/20 Production Year, against an equivalent volume of consumed electricity. 

In future years, as the volume of certificates transacted increases, the difference between the National Supply Mix and the Residual Supply Mix will increase.