Light-rail plan requires boost to power grid
A light-rail network in Christchurch would force an early upgrade of the city's power grid, new research suggests.
Lincoln University academics Agathe Grenier and Shannon Page, from the department of environmental management, have studied the potential impact on Orion New Zealand's electricity network of introducing light rail to central and western parts of the city.
As well as accelerating a grid upgrade by about four years in west Christchurch, a light-rail system would require the grid to provide several megawatts of extra electricity to be able to operate at peak times.
They also found that the Fendalton substation would be the most affected by the electricity demand of light rail, although given current power-use projections, it should be able to cope with the increase in power load until 2015.
If there were no light-rail system, the substation would not need upgrading until 2019.
The researchers said overall power demand from a growing fleet of electric vehicles would be "significantly higher" than demand from a light-rail line providing the same number of passenger kilometres a day, but light rail would have more impact on peak loads.
In their paper in journal Energy Policy they compared a possible light-rail system in Christchurch (population 377,000) with that now operating in the French city of Orleans (population 369,000).
They assumed the Christchurch City Council proposal for a 15-kilometre line from the central city to the airport would have similar features to the 18km system in Orleans, operating from 5am to midnight, with trains every nine minutes and an average travel time between stops of 2 minutes.
Ten trains would operate at peak time, between 7am and 7pm, with between two and eight running outside that period. Trains would stay at each station for an average of 20 seconds.
Their modelling revealed that the Fendalton substation, in the central part of the line, would be the most affected on the route. At peak times it would power up to four trains, as well as other electricity demand.
Orion's load forecast predicted an 8.8 per cent increase in peak load for the substation between 2010 and 2020.
With light rail added, the substation's maximum capacity would be reached in 2015, not 2019.
"One light-rail line could be sustained in Christchurch for a few years before upgrades are required on affected substations," Grenier and Page said.
"Although the impact on the local grid is higher, the overall energy demand of light rail is lower. [However], electric vehicle charging during peak time may overload several substations.
"The unplanned introduction of electric transport would put the local distribution network at stake."
- © Fairfax NZ News
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