Quick Dips

Wasted Water, Pricey Power

The Institution of Professional Engineers is concerned that electricity generators have been spilling water at hydro stations, while using large amounts of natural gas in thermal power stations, suggesting that commercial interests are being put ahead of environmental or efficient use of resources.

"Electricity generators are therefore simultaneously wasting a valuable renewable water resource and squandering natural gas. This is an inefficient use of resources and is also not in accordance with the government's international commitments to limit the discharge of carbon dioxide emissions into the atmosphere," says IPENZ spokesman John Blakeley.

"Any consideration of environmental issues and efficiency of resource use appears to now be `right at the end of the chain' in their decision making processes. If this is already happening now, it is rather frightening to contemplate the consequences of the further split of ECNZ into three companies from April 1 next year with more competitors entering the marketplace all following thie own goals"

Following a relatively mild winter combined with high rainfall, South Island lake levels are near full capacity or spilling. Traditionally, hydro storage in the South Island is planned to be at empty by October to be able to catch all the spring rain and snow melt. By mid-November the lakes would normally still be less than about 70% full to allow for catching further inflows from snow melt. This year with the lakes already full it is now too late to prevent large volumes of water being spilled.

Blakeley says that if hydro lake storage was being managed as it used to be, South Island electricity generation would be higher, the inter-island electricity transmission link would be running at full capacity and thermal generation would be reserved for periods of peak demand.

"Instead over the past few months South Island hydro stations have spilled water, the inter-island electricity transmission link has been running mainly at less than half of its 1000MW capacity and the New Plymouth thermal power station and the new Taranaki Combined-Cycle power station at Stratford have been operating day and night at more than 300 MW each."