Greg Hewgill (ghewgill) wrote,
Greg Hewgill

electricity in new zealand

When you live on a remote island in the South Pacific, you can't buy your electricity from anybody else. Fortunately, New Zealand has many raw sources of energy: Hydroelectric, geothermal, wind, gas, coal, etc. The South Island has primarily hydroelectric generation, while the North Island has the rest. There is a High Voltage DC Inter-Island link that connects the two islands so they can swap power when needed. The direction of this link is almost always northward, to use the excess generation capacity from the South Island hydro stations. The latest released New Zealand Energy Statistics report shows this lopsided split, as the "Hydro & wind" approximately represents the South Island and "Thermal" represents the North Island.

The news today has a number of conflicting reports about this coming winter power usage. There has been lower than normal rainfall and the lake levels are at about 58% of full capacity, which is the lowest level since 1992. A small selection of headlines tells the story:

The Energy Link site publishes the Market Review report which has tons of info like wholesale electricity price trends, generation trends by time, generation proportions by source, daily demand trends, HVDC transfer direction and volume, estimated CO2 emissions, and more. The net energy transfer over the HVDC link became southward over a month ago.

The last article claims that all the country's power is presently being supplied by thermal stations on the North Island, and the Inter-Island link is configured to transmit power southward. Since that is not its primary direction, the link has less capacity in that direction than northward (600 MW southward; 1040 MW northward).

All this indicates to me that the situation is a bit more dire than the politicians would like to admit. The power industry has set up which intends to inform people about the situation and how to conserve power. That site shows the lake storage below average, the lake inflows below average, and both the average demand and peak demand as high as they have ever been.

What could possibly go wrong?


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