Climate change may be good news for hydro power, grapes

Warmer temperatures and their impact on New Zealand’s hydro-power potential may be a rare bit of good news on the climate change front.

Hydro-generated power already accounts for more than half of the country’s total electricity, 80 per cent of which comes from renewable sources.

In the South Island, the Waitaki scheme generates 1728 megawatts of power and the Clutha scheme 752MW.

In the North Island, power stations along the Waikato River generate 1059MW.

National Institute of Water and Atmospheric Research hydrologist Dr Daniel Collins told the joint Meteorological Society-Hydrological Society conference in Christchurch yesterday that there was good news about the future of the national hydro-power system.

Modelling of hydro schemes in both islands with climate change showed ‘‘signs’’ of a rise in potential hydro generation in the South Island, even during drought, but a decline in the North Island.

Nationally, there could be a 14MW increase in power, about 3 per cent of installed capacity, he said.

The models did not take into account changing demand patterns – such as a rise in summer peaks due to an increase in the use of air conditioning – or what it might mean for the ability to transmit electricity across the high-voltage, direct-current, inter-island Cook Strait cables.

‘‘We are going to have stronger westerlies across New Zealand, dumping more precipitation in the Alps, in the headwaters of these schemes.

‘‘That is one of the strongest messages from climate-change projections that we have. But that signal is weaker in the north. But nationally, because the South Island generates so much, it more than compensates for the possible declines in the North Island. So, hey, this is a positive news story about climate change,’’ Collins said.

University of Canterbury geography emeritus professor Andy Sturman said projected warming over the next few decades was also good news for cool climate grape-growing in New Zealand. ‘‘We will actually benefit from climate change.’’

Weather observations from intensive networks set up in the Marlborough, North Canterbury and Central Otago wine-growing regions had been fed into models.

It was a question of growing the right varieties. One or even 2-degree Celsius rises for sauvignon blanc grapes would make little difference because the variety was ‘‘pretty robust’’.

‘‘We do have time. You plant your vines for 30 years. At the end of 30 years you pull them out and put some other ones in. So you can actually plan ahead over the decades.’’