Genesis boss Marc England has rejected claims New Zealand had enough power to handle the unprecedented demand last night, but that commercial decisions had prevented it.
However, Genesis chief executive Marc England told Checkpoint his company was being scapegoated by Woods, and denied it was commercial decision to have less supply. He said it had been an operational decision.
"Genesis is just one of several generators. We actually lost a lot of money yesterday... more than $1 million," he said.
England said a build-up of weeds in a hydro lake and a lack of wind for turbines had hampered supply.
Transpower apologised this morning over the cuts on one of the coldest nights of the year.
It has assured customers that power will not be intentionally cut again tonight.
Transpower grid development general manager John Clarke told Checkpoint extra generation had been made available after thousands of New Zealanders were left in the dark last night.
Woods this afternoon said she had confirmed there had been capacity to handle the demand of 7100 megawatts, and the situation could have been prevented.
"This wasn't a physical constraint of generation, we did have the ability to physically generate the amount of electricity that would have been needed to keep the lights and the heaters on for New Zealand last night but commercial decisions were made not to."
She said generator Genesis had decided not to turn on its third generator at Huntly.
"The third rankine (generator unit) at Huntly was not turned on because Genesis made a decision that there wasn't going to be that much demand in the system."
She would be seeking more answers about whether Genesis' decision to shut the generator off was an intentional move to keep power prices high.
She noted that another concern was the coordination of the generator companies.
"The individual operators and generators only really have line of sight into what they're doing," she said.
"Things did change throughout the day, the wind did die down so that meant some of the wind generation went off. I think that once we get through and we can give reassurances for people that this isn't gonna happen tonight, that there are some obvious questions that still need to be answered for me."
Transpower, the state-owned enterprise which owns and operates the national grid, has responsibility for overall system operation, and Woods said about half the amount of power cuts could have been made.
"Seems that there was an overestimation by Transpower about how much needed to be shedded. The number that they were putting out to the distribution network, to the lines companies was that 2 percent needed to come off. It seems like that was probably double estimate of what needed to be shedded."
Genesis said Tanspower did not ask it for more electricity until just after 5pm last night on the cusp of the evening peak demand.
The company said it did increase supply at its Tokaanu site but gale force winds earlier in the day had pushed weed into the intake at the plant, which ultimately tripped, losing 115 megawatts of generation.
It said elsewhere it was operating at full capacity.
Transpower has assured customers that power won't be intentionally cut again tonight. Its general manager of grid development, John Clarke, says extra generation has been made available.