NZ hydro lakes brimming with energy

With hydro lakes full, the average wholesale electricity price paid to Contact Energy in the first three months of 2007 was less than half that of a year ago.
The price in the most recent quarter was $NZ43.25 ($A38.68) per megawatt hour, compared with $NZ115.83 ($A103.58) in the first three months of 2006, the company said on Tuesday in its quarterly operational report.
The lower prices reflected differences in hydro lake levels, which were 105 per cent of mean at the end of March this year, compared to 65 per cent at the end of March 2006.
Contact's total generation for the first three months of 2007 was 2388 gigawatt hours, 17 per cent less than a year earlier.
Hydro generation was 862 GWh in the most recent period, compared to 737 GWh, reflecting higher inflows into the Clutha River catchment.
Geothermal generation was up 7 per cent to 467 GWh, while thermal generation was down 38 per cent to 1059 GWh.
Contact Energy's ten power stations include hydro stations at the Clyde Dam and Roxburgh, in Central Otago, the Wairakei geothermal station near Taupo and gas-fuelled stations in Otahuhu and Taranaki.
It produces about 25 per cent of the country's electricity.
Shares in Contact Energy, slightly more than half-owned by Origin Energy of Australia, were down 10c to $9.01 around 2pm on Tuesday.
While hydro lake levels may have been good at the start of the year they have since fallen away and are now at 73 per cent of average for the time of year.
Levels have been below average since part way through February and recently dropped to below the level at the corresponding point last year.
Early in 2006 concern had mounted that an electricity crunch was on the way as hydro lake levels tracked those of 1992 when the country last faced a major power shortage.
At the start of April 2006 storage was down to 65 per cent of average, but then it rained heavily and the problem was averted, even though levels remained below average well into November.
Now levels are again falling further below average but the industry appears less concerned than early in 2006, one reason given that Genesis Energy's gas turbine e3p (for energy efficiency enhancement) project at Huntly is being commissioned.
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