NZ: Winter power shortages loom
Electricity companies and industry are in talks about a looming hydro power shortage this winter.
25 February, 2012
South Island generators and national grid operator Transpower said they are watching things closely as national hydro storage this week dropped below where it was the same time in 1992, three months ahead of that year's major winter power crisis.
But they emphasised it is still early days and that a couple of heavy rainfalls in the south of the South Island or the catchments of the Waitaki River system could alleviate the low lake levels
Rain on Thursday eased the situation slightly from where it was midweek.
The latest figures, compiled on Thursday, show national hydro storage at 2379 gigawatt hours (GWh), very close to the same level on February 22, 1992.
South Island hydro storage is at 1867 GWh, or 67 per cent of the long-term average.
The level of Lake Pukaki, at the heart of the Waitaki system, which generates about one-quarter of the country's power, stands at 54 per cent full in generating terms .
Lake Tekapo is 70 per cent full.
Further south, dry weather is responsible for even lower lake levels, with Lake Te Anau at 43 per cent full, and Lake Manapouri also 43 per cent full.
The inter-island high-voltage direct current (HVDC) link has reversed its usual flow, carrying power southwards for about the last five weeks.
Kieran Devine , general manager of system operations for Transpower, said the company had been dealing with the situation as if it were a "regular transmission problem".
"Lakes at the bottom of the South Island are a lot lower than those further north."
Some rain had fallen in the Waitaki catchments over the past day which should help, he said.
"It's a good sign it is raining in those catchments, even if all it does is soften the ground up so the next fall doesn't drain into the ground.
"After that, the forecast for the South Island is average to slightly below average [rainfall] over the next few months. So a forward look is positive to neutral."
Transpower had had four industry meetings to discuss the situation and ways to juggle the constraints on the inter-island link ahead of its upgrade later this year.
"The principle issue is getting the power off the link at Benmore and into the deep south." Meridian Energy general manager of markets and production, Neal Barclay, said the company was monitoring lake levels.
"It's an area we have to watch carefully. But if we look forward we would still expect there is a better-than-average chance they will bounce back before winter.
"There are no guarantees around that, so we have to operate in a relatively prudent manner, reducing the amount of hydro generation and bringing thermal [power] on in the North Island."
Genesis spokesman Richard Gordon said Genesis and Meridian had water management agreements in place that meant they would work together on the use of water in Lake Tekapo and Lake Pukaki. The higher level of Tekapo was "not a case of us holding water back".
"We have to manage it through Tekapo A and B [power stations] to meet our South Island customers' needs. We have 60,000 [South Island] customers now."
Auckland electricity consultant Bryan Leyland said it was still too early to worry about a winter power crisis.
"But in the days of the old NZED [New Zealand Electricity Department], it would be thinking about how it could be building up storage now in the lakes."