“Effectively, if you become stranded from the grid on the East Coast or the North Island, you’re relying on the generation from that area to power your own homes or businesses,” he said.
“So the team here are really proud of what they’ve achieved,” said chief wholesale officer Tracey Hickman.
“Without the power station, the lights could have been out for the whole region for a long amount of time.”
Hickman pointed to the Onepoto intake structure and said “as you can see, there aren’t any floodgates to open”.
After the cyclone Genesis commissioned an independent review which found that their water was only responsible for 1 percent of Wairoa’s flooding. The Wairoa District Council is conducting its own review of this data to verify the report.
The rest of the flooding was overflow from streams and rivers, Hickman said.
Before the cyclone Genesis had seen the weather forecasts and intentionally lowered their lake by 6 percent to reduce the possibility of overflow.
During the flood they had to flow the water according to the resource consent rate of between 35-40m³ per second.
Hickman said the resource constraint is there in case of uncertainty on whether there will be “lots more rain, or no rain — potentially you’re going to get a mixture of both”.
“It’s a balancing act, which is why we have minimum constraints and maximum constraints to try to manage rain.”
General manager for media and communications Chris Mirams said Lake Waikaremoana operated approximately 5.5m below the natural lake level, which enabled flood flows to be stored rather than passed directly downstream.
A Genesis team member said: “Without the power scheme, there’d be no control of the lake water. So this scheme actually becomes a safety control point for the river flows”.
During the media tour, Genesis’s efforts to decarbonise New Zealand featured heavily.
Hickman, who has a Masters degree in environmental studies, said the electricity sector had an important part to play in decarbonising New Zealand.
“Genesis is investing really heavily in solar farms and, over time, in wind farms,” she said.
“One of the big constraints around solar and wind farms is, it’s great when the wind is blowing and when the sun is shining, but you need to diversify when that is not available.
“In New Zealand that’s hydropower schemes, but currently dry winters are a huge problem for us, when the rain does not come.
“So, we are planning a large grid scale battery at our Huntly site and these might increase in years to come because that provides intermittent grid firming, when the sun and the wind come and go.”
Hickman said Genesis was also exploring the possibility of biomass, which is the process of turning wood pallets into energy. Forestry slash could potentially be used for this, she said.
“Genesis still has the Huntly power station (which is run through coal and gas) and New Zealand depends on that power station when the hydro lakes are low.
“We’re all working really hard to see if we can just replace coal with something more renewable.
“The benefit of biomass is when you do not need it you are are able to store it.
“And then you have it available when the hydro lakes are low,” she said.
