Electric transportation and the impact on local electricity management: a case study of electric public and private transport in Christchurch, New Zealand.

Abstract

Electric transport such as a light rail transit (LRT) system and private electric vehicles (EV) are power intensive systems and are likely to add significant pressure on the electricity distribution network, especially during peak times. This study estimates the impact of both private EVs and a public LRT system on the local distribution network using Christchurch, New Zealand as a case study. The number of plug‐in EV in Christchurch in 2010 is insignificant (R. Hay, personal communications, October 20, 2010). To evaluate the impact of a future EV fleet, an analysis of the current light hybrid vehicles location in Christchurch highlighted that future EV owners will not be evenly distributed across the city. For instance, one out of 30 local power substations may have to supply 14% of Christchurch electric cars. If users charged their cars after their final daily commute, which often coincides with peak electricity, substations such as the one in Fendalton would reach their full capacity if EVs represent more than 3.5% of the Christchurch private light vehicle fleet (7700 EVs in Christchurch). However, implementing demand side management (DSM) would allow a higher EV uptake (up to 11.4%). While Christchurch does not currently have a LRT system, a light rail network has been modelled to identify which local distribution substations would supply the line in Christchurch. The Fendalton zone substation would be one of the main power supply substations and was found to have enough spare capacity in 2010 to provide the additional power demand. Despite regenerative breaking systems and smart management to reduce the maximum power demand of a LRT system, forecasts show that an LRT introduction would require earlier infrastructure upgrade (2015 instead of 2019 in business as usual) to keep up with growing demand. A comparative analysis shows that the maximum power demand from an EV fleet is six times higher than maximum demand from a LRT system on a similar number of passenger kilometres per day basis. However, DSM options would allow shifting all EV fleet demand off peak time whereas although LRT demand can be reduced, it would still contribute to peak load. Therefore, the LRT would have a great impact on the local distribution network than an EV fleet.