NZ Battery Project manager Dave Darby said when Cabinet approved the phase one, "indicative business case", for Lake Onslow, it asked staff for more detail on several technologies that looked like they might be "promising alternatives".
"We’ve got a lot of information about Lake Onslow, but during the past couple of years it’s emerged that there are other technologies, like hydrogen, or biomass or geothermal, that could potentially play a really important role."
There would be further investigation of those alternatives before work began on the detailed business case, Dr Darby said.
The Government announced this week it would proceed to the next stage of the NZ Battery Project, looking at the viability of pumped hydro, as well as "an alternative, multi-technology approach".
The Ministry of Business, Innovation and Employment launched the NZ Battery Project in late 2020 to look for solutions to New Zealand’s "dry year problem".
When hydro-electricity lakes run low during dry years, coal is burned at Huntly Power Station to make up the electricity shortfall.
Potentially turning the man-made Lake Onslow into a much larger lake and pumping water up into it, to be released as required for electricity production, has been a major part of the project’s first phase.
Phase two will include creating a detailed business case for it.
"We’ve really only scratched the surface of what we need to understand about the environmental impacts in particular," Dr Darby said.
"And we need to do much more study, and much more discussion with the local community about the social impacts, both positive and negative.
"I do feel that if the project does proceed there would be a short-term benefit to the community from the construction project, which would be major.
"But it would be, and I’ve heard this from many landowners and stakeholders in the area, that they are looking for a long-term benefit beyond the simple construction project.
"And I think for a scheme of this kind ... it’s really important to be aware of what it could bring to the community, so we will want to be looking at this."
First though, emerging renewable alternatives would receive due consideration, Dr Darby said.
Biomass was seen as renewable energy because it largely involved burning trees that had taken carbon out of the atmosphere.
Genesis had also successfully completed a biomass burn trial at Huntly Power Station, he said.
But more work was needed to understand the volumes of biomass required and the costs of the supply chain.
Second, New Zealand’s geothermal resources could possibly use technology allowing them to ramp up or down production as needed.
Third, there was quite a lot of interest internationally — and from New Zealand companies — in hydrogen, he said.
"We’re quite interested in tapping into that knowledge and learning how it could potentially help address the dry year problem.
"There’s lots of discussion internationally at the moment about how hydrogen can play a role in the energy transition if it is hydrogen made from green sources, using renewable electricity.
"It’s really a storage medium for electricity, and we are very interested in this as a potential storage solution."
However, not one of those alternatives alone would add up to enough, Dr Darby said.
"We’re probably going to have to look at all three."
The first phase of the investigation concluded Lake Onslow could fill the gap.
Largely through Ōtākou Runaka, local iwi were engaged with the work, he said.
"I think Ngāi Tahu are very interested in Onslow, but I don’t believe they have yet stated any firm position on it."
Preliminary engineering, geotechnical and environmental investigations would soon be made public, but first the indicative business case and the associated Cabinet paper would be released later this month, he said.
