New Zealand's only standby dry-year power station at Whirinaki near Napier, has swung into operation, signalling increasing concerns about low hydro lakes and whether there will be enough power next winter. A Genesis Power spokesman said the company was importing 200,000 tonnes more coal next year than it had this year.Electricity Commission chairman Roy Hemmingway said hydro lakes usually started to fill at this time of the year, but hydro storage was falling. The 155-megawatt Whirinaki power station near Napier ran for about five hours yesterday and for an hour and a half on Monday. Whirinaki starts in response to spot market electricity prices over $200 a megawatt hour, under an established protocol set by the commission. A month ago spot prices were about $65MWh and by last week they had risen to $130MWh. Mr Hemmingway said the climb in spot prices to more than $200MWh on Monday and yesterday signalled generators' concerns about low storage and that 600MW of thermal plant (a 250MW unit at Huntly and Otahuhu B power station) was out of action for summer maintenance. "While we still don't see a major reason for concern because we are still not seeing a historical inflow sequence that empties the reservoirs, we thought it was prudent to let people know the risk has increased," Mr Hemmingway said. The commission uses 78 years of data to make its assessments of risk to security of supply. Mr Hemmingway said the eight weeks before the most recent rainfall were the third driest for that time of year in 78 years. It was still too early to estimate power supply for next winter, he said. In 2001, very low reservoirs filled in six weeks at about this time of year. Meridian Energy spokesman Alan Seay said yesterday: "There is a level of concern at Meridian about power supplies next winter." Meridian is the biggest hydro power player and has the two biggest hydro storage lakes at Pukaki and Tekapo in the South Island. Mr Seay said the lakes filled up between spring and early autumn, so there was still a lot of time for the needed big inflows to occur. Concern would rise if Meridian's lakes were not close to full approaching winter, he said.
