Does the NZ Emissions Trading Scheme affect retail petrol prices?

Of course, my title asks the wrong question. The more policy relevant question is "How much does the NZ Emissions Trading Scheme affect retail petrol prices?

The Ministry of Business Innovation & Employment has a page on weekly oil price monitoring and some week by week data on petrol prices. I made a R chart from that data.

Click on the image for a decent sized graphic.

The NZETS component of the NZ retail price of petrol pretty much just hugs the zero point on the vertical axis.

A note lower down the web page states "The costs associated with the ETS are provided by Hale & Twomey based on the prevailing carbon price from the New Zealand Carbon Market". So we need to note that this data is an estimate.

Over the four and a half years of the NZETS, the estimated NZETS component has ranged from a maximum of 2.4 cents per litre from late 2010 to June 2011 to a minimum of half a cent from July 2013 to December 2014.

As far back as 2007, the Labour Government predicted that petrol prices may rise up to 4 cents a litre possibly based on carbon price of $25 per tonne. From memory, the early 2011 price for a NZ unit was about $21 a tonne.

Wikimedia Commons has the R script I wrote for the chart (except it's a .svg file, not a .png).