Hydro Lakes Seriously Low During April

New Zealand’s hydro-electric storage lake levels remained seriously low during April 2008. Levels were dramatically lower than April last year, electricity demand was steady and inflows were seriously deficient.

At the beginning of April 2008, New Zealand’s hydro-electric storage stood at 2285 GigaWatt hours (GWh), 73% of average for the time of year. By month’s end, this had declined to 1919 GWh, 63% of average. Storage steadily declined during the month, roughly paralleling the April 2007 trend. However, storage was dramatically lower than April last year when storage hovered between 72% and 90% of average, and was closer to the levels recorded during the 1992 crisis year.

Inflows were below average on 26 days, and seriously deficient (below 50% of average) on 9 days, reflecting the dry conditions. Above average flows into the lakes occurred on the 15th, 16th, 29th and 30th of April.

Demand was close to April 2007 figures, with average daily demand being 103.9 GWh compared with last April’s figure of 103.5 GWh. Two days of peak demand occurred during April 2008 when load reached 109.6 GWh on the 10th and 109.7 GWh on the 15th. Last April’s peak demand of 112.5 GWh occurred on the 28th.

Tight management of resources saw steady transfers via the Cook Strait cables, with north to south transfers exceeding northbound transfers on 15 days.

The Outlook: The 80-year average shows that inflows decline slightly during May and June and reach their minimum toward the end of July. Storage declines steadily over the same period, owing to steady winter demand for electricity. The National Institute for Water and Atmospheric Research outlook for April to June is for warm conditions over most of the country, and rainfall is expected to be near normal in most places.

[Compiled from data supplied by M-co.]

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