6 May 2021

Extended dry conditions may set New Zealand back in zero carbon mission

2:43 pm on 6 May 2021

The prospect of a dry winter, which will prove a challenge for farmers, may set the country back in its transition to a zero carbon economy.

Canterbury region farms

Photo: RNZ / Nate McKinnon

While farmers will be making hard decisions about stock and feed for the coming months, the energy sector is also being looked at as a means of combatting future dry conditions.

Victoria University professor Justin Hodgkiss, who also co-director of the MacDiarmid Institute, told Morning Report the country had high renewable electricity generation, mostly due to hydro.

However when that drops in a dry year, it means the gap needs to be filled via other means - like coal and gas.

"It's not just this year - it gets worse in the future for two reasons. One [is] we can expect more dry years in the future with climate change and, two, we are going to be needing a larger electricity supply to cope with the electrification of transport in particular," Prof Hodgkiss said.

"Electric vehicles will dominate our fleet in the next decade or so. Also electrification of industry is high priority to decarbonise in general."

Storage options for renewable energy was part of the solution, he said.

"The big option that's being explored right now is the pumped hydro possibility in Lake Onslow, so that's being termed the 'New Zealand battery project'. 'Battery' in a metaphorical sense, whereby water is basically pumped back into a reservoir when there's excess renewable energy, such that you can discharge the battery when you need it."

The project had the capacity to solve problems during a dry year, however, it was an expensive solution, Prof Hodgkiss said.

This would be weighed up by the government against other options, like hydrogen, biomass and overbuilding renewable energy supply.

"I think probably there's going to be a mixture of all these things required. The interim Climate Change Commission put costs on all of these options in terms of their ability to reduce carbon. They think pumped hydro is the cheapest. But there are large error bars because increased RND can lower the costs of these other things over time."

AgResearch senior scientist Dr Robyn Dynes told Morning Report this autumn had been so dire in parts of the country to the point that some farmers have not managed to accumulate enough feed to carry them through winter.

"Beef and Lamb New Zealand and DairyNZ have both been pushing out resources for farmers over the past couple of months, because the rain has not been falling for a couple of months.

"For farmers, it's [about] looking ahead, it's knowing where they are now and where they are going to be if they go into winter."

The next challenge will be Spring, because rainfall during winter fills the dams and helps the soil so that when the warmth sets in again, it enables a lot of pasture growth for farmers.

Although farmers had pasture-based supplement feed set aside in storage specifically for these situations, Dr Dynes said whether that would suffice depended on how long the dry conditions lasted.

There was also cross-industry support available for farmers, but that could also be threatened by an extended dry period.

"You'll recall in the past we've seen massive truckloads of silage being transported from an area that's not in drought to another area that's in drought, so the spread of the drought impacts on our capacity to shift pasture-based supplements around the country," Dr Dynes said.

Farmers would be making decisions to try and keep the impacts of this year limited, she said.

"The great thing about rural communities is you won't be the only one in that situation. Through the Rural Support Trust, Beef and Lamb New Zealand, DairyNZ - they're already running community events where people can share their learning and thinking."

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