Locals concerned proposed Waerenga solar farm will heat valley by 2C

Locals in the Waikato valley of Waerenga say plans by a UK-based company to build a solar farm, fail to address concerns it could increase the temperature in their valley by several degrees.

Island Green Power and its NZ arm Waerenga Solar Farm Limited have applied for resource consent, with Transpower, to build and operate a solar farm on 85-90 hectares of land in Waerenga.

The project will provide power to 46,000 homes, with 290,000 silicon panels feeding the national grid from three properties on Waerenga Road, Keith Road and Awariki Road.

But many locals argue the area, which is home to dairy farmers, fruit and vegetable growers and a wetland, will suffer.

"The lack of communication from Island Green has been appalling. They've had two years to put their proposals together; we had 15 days, some people in the community only got six," said Roger Mackinven, who will look out on the proposed site.

Resident Courtney Howells told Newshub he is not against the idea of a solar farm, but is concerned not enough work has been done to ascertain whether it'll trigger a "heat island effect" in the Waerenga Valley, which already gets up to 28C in summer.

"I don't think we should go ahead until we have some clarity around what impact a heat island effect of maybe 1-2C has on this valley."

NIWA's chief scientist overseeing climate, atmosphere and hazards told Newshub while there is no real evidence of this in NZ yet, "research carried out at solar farms in China and the USA indicate that solar farms can warm the air immediately above the panels by up to around 2.5C in the mid-afternoon."

Dr Andrew Tait said "at around 20 metres above the panels there is no longer a noticeable difference in temperature from the ambient conditions".

This localised warming is often referred to as a "PV heat island".

"You might expect a similar effect if a solar farm were operating in the Waikato, but this would need to be studied in detail."

Courtney Howells said Waerenga is a unique site to build a solar farm, given its proximity to Lake Waikare. The lake already absorbs heat, making the area prone to intense downpours that he feels could see further sediment run into the nearby wetland.

"If Island Green has got other sites with a similar environment, a large lake that evaporates, a wetland that is precious and they have evidence to show there is no impact then let's produce it."

Howells is urging the government-appointed independent consenting panel to "make sure we are not making a mistake cos it's too late once the green button is pushed".

Island Green Power is registered in Bermuda and has built 21 solar farms around the world.

If granted resource consent, it will lease Waerenga farmer Ross Laing's land for 40 years. He considers the heat island effect "a red herring".

"If you remove 500-600 cows off the land and the inputs like sprays and fertilisers, under solar panels it'll be sheep. It'll be purely organic, less intensive with more planting around rivers and waterways. If you want to talk about an environmental point of view, I think it's a really great thing for the valley."

Island Green has failed to respond to multiple requests by Newshub for comment.

Documents before the Environmental Protection Authority's independent consenting panel from its advisors say: "Studies of solar farms in arid environments where scrub vegetation had been removed have observed a temperature increase. However, Waerenga Solar Farm Limited (WSFL) is not aware of any recorded heat island effect at a solar farm installed on pasture with surrounding vegetation."

It says there is no reason to believe that a temperature increase would occur at Waerenga Solar Farm.

"They haven't seen Waerenga in a drought, it goes brown," advocate for Waerenga locals John Keith said.

Waikato-Tainui, Ngaa Muka and the five marae it represents "is supportive of renewable energy provided the social, environmental, cultural, political and economic effects of these solar farms being proposed in our backyard are done in partnership with Ngaa Muka."

Iwi spokesperson Haydn Solomon would not comment on why Ngaa Muka initially opposed the solar farm but later changed its stance. On November 1 it advised the Environmental Protection Authority it has "reached an in-principle agreement" with Island Green Power that addressed any concerns it had.

"With regard to the issue of heat effect, no evidence has been tabled in this consent process to substantiate such claims," Solomon said.

He said "if there is increased sediment coming into the wetland then there needs to be debate" but for now iwi support the project.