Cook Islands Wants Battery System To Ease Burden On Power Grid

ADB asked to support installation of utility scale battery storage

By Cameron Scott 

RAROTONGA, Cook Islands (Cook Islands News, August 18, 2016) – Te Aponga Uira is working with the Asian Development Bank on the installation of a utility scale battery storage system to ease pressure on Rarotonga’s electricity grid, says TAU’s chief executive, Apii Timoti.

He says the new system will ease pressure on the existing grid and to allow further integration of renewable energy installations such as solar electricity systems into its network. 

“When this is implemented, TAU will be able to lift the limit on further solar installations. We are still in the process of working through the project requirements with the ADB and hope that this will be on line in 2017.

“On this point, to ensure costs to our customers remain reasonable, grant funding and concessional financing is key.

Timoti would not comment on the cost of the project, which will be funded through the Global Environment Facility. However, its completion next year will come as a relief to solar power system installers, one of whom says his business has been crippled by TAU’s sudden restriction on the installation of new systems. 

Commenting on a proposal by Chris Vaile of Triad to establish a pilot pumped hydro power installation in the Te Reinga o Pora Valley, Timoti said TAU had in fact been researching hydro-electricity for the last two years, although on a much larger scale than that proposed by Triad. 

“We are aware of the Triad proposal but since it is a commercial venture, we have had very little involvement.

“This is not to say that we do not want to be involved.

However, we would prefer to take a cautious approach and see how this would fit into the developments also anticipated by TAU in relation to the entire power system which we are approaching through a planned process over the next six months. 

“It is fair to say that all storage options are being considered including battery and pumped hydro.”

Though pumped hydro systems had low maintenance costs throughout their life, they had high initial installation costs, Timoti said.

“The pros and cons of all storage options need to be considered and we are doing this.”

In a letter sent to landowners in the area where Triad’s proposed pumped hydro system would be installed, lawyer Tim Arnold claimed while batteries could be a good way to store small amounts of power, Te Aponga would need to store huge amounts of power every day.

“It could cost close to $100 million for all the batteries needed to store the island’s night time power needs and Te Aponga would have to spend big money every time those batteries needed to be replaced.”

Arnold said it would cost around $7 million in batteries to store the same amount of power as the proposed pumped hydro system.

However, Timoti said battery technology was evolving and constantly improving both in terms of application and cost.

“Although considered expensive now because of high replacement costs, with new developments globally this could be cheaper in the future.” 

Timoti said the road to renewable energy involved high capital and ongoing fixed cost transformation from a power system with high variable costs due to changing fuel prices.

 “We cannot comment on the figures provided by Arnold. However, the lifetime of the asset needs to be considered when we talk figures. A large-scale pumped hydro system generally has a life of around 90 years.”

Research shows that battery systems are now being used to stabilise power distribution networks in small countries and on islands around the world. Timoti says Rarotonga’s utility-scale battery will be a “time shift storage solution” and will be put out for public tender in coming weeks. 

“We expect commissioning in mid-2017,” he said.

“This is a grant-funded project and therefore the set up costs are covered with the fixed ongoing costs being minimal. 

“Our ideal is to progress government’s target through upgrading our power system with grant and concessional financing to minimise ongoing costs, and therefore end cost to our customer.  Timoti said government’s 2020 target date for the Cook Islands to be 90 per cent reliant on renewable energy was one that TAU “endeavoured to progress towards” and would involve input by all stakeholders on Rarotonga including landowners, the private sector and funding agencies. While he would not be drawn on whether the target date was realistic, other commentators have said it is unlikely to be achieved.                 

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