Hydro spills prove need for extra storage - expert

Media Release
January 9, 2009

Hydro spills prove need for extra storage - expert

People holidaying in the South Island should make a diversion to view the spectacular spills from the Benmore Dam on the Waitaki River so they can see their winter power savings flowing away.

That’s the view of hydro expert, Waikato University Associate Professor Earl Bardsley. Dr Bardsley, from the university’s Earth and Ocean Sciences department, says the water loss highlights New Zealand’s vulnerability to insufficient energy storage capacity in the South Island hydro lakes.

Meridian Energy has this week been spilling water from several of its South Island hydro lakes which are now full, despite last winter’s power crisis when the lakes dropped to very low levels.

Dr Bardsley says last winter’s electricity saving campaign saw less power used, but because the campaign stopped the lake levels from falling further, there isn’t enough room to store summer water.

He says the campaign was necessary, and the power companies are simply doing their best with hydro storage systems unable to cope with natural climate variations, but it highlights the need for a large pumped storage scheme to be built in Otago. “This would provide winter electricity supply while keeping the hydro lakes at stable levels to allow room for storage when summer floods come. There is no way of forecasting these high summer flows, but extra storage would allow for that and avoid these situations.”

Spills at the Clutha and Waitaki hydro schemes are not common, but represent lost generating potential which cannot be held over to offset the next dry period, Dr Bardsley says. “Spills from Lake Tekapo are particularly significant because this represents simultaneous losses from five downstream power stations which get bypassed by the water.”

He says this week’s spills also prove that renewable energy is not always the answer either.
“If large wind farms in the South Island had been available last winter, their power would have been used to maintain the level of the hydro lakes and would have resulted in even larger spills than at present.

“It’s possible that new wind power schemes in the South Island will generate no net power when there are summer spill losses,” Dr Bardsley says.

ENDS

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