Cook Islands Boosts Microgrid Capabilities with Storage

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Rarotonga, the remote South Pacific island that is part of the Cook Islands, plans to boost its microgrid capabilities with new energy storage capacity.

Cook Islands

Rolls-Royce has been awarded a contract to supply three 40-foot MTU-brand battery containers for a microgrid on the Pacific island of Rarotonga. Photo courtesy of Rolls-Royce

Under the terms of a deal signed with New Zealand’s Vector Powersmart, Rolls-Royce company MTU will supply three containerized battery storage units.

The MTU EnergyPacks, packaged in standard 40-foot shipping containers, will  support the microgrid while enabling the increased use of variable renewable energy. These units will be integrated by Vector into an existing power plant run by local utility Te Aponga Uira.

It is the third such project the integration company has developed with Rolls-Royce, including one on the nearby island of Aitutaki where a 20 foot battery container has been controlling the microgrid since 2019. In New Zealand, a 130 kVA containerized battery also stores excess power from a photovoltaic system at a resort in Glenorchy for use at night time.

Rarotonga’s microgrid supplies about 11,000 island inhabitants and includes photovoltaic systems, diesel gensets and batteries. The new MTU units will add a total storage capacity of 4,268 kWh and a power output of 4,800 kVA. Along with lithium ion batteries, the MTU EnergyPack houses an electronic control unit, transformers, and cooling equipment to form a complete energy storage system.

The development comes as Rolls-Royce plans to significantly expand its PowerPack production capacity at the Siemens-Technopark at Ruhstorf in Germany’s Bavaria. This new production capacity will be available from early 2021.

With some of the world’s highest electricity costs, the Cook Islands are looking to boost renewable generation capacity with backing by the Asian Development Bank (ADB), the EU, and others, according to the Ministry of Finance and Economic Management. The goal of the program is to deliver solar renewable energy to all five of the Southern Cook Islands by 2020. Under this $24.28 million project, each of the solar power plants built on the southern islands will have a total capacity of around 3 MW. Collectively, the renewables and microgrid installation are anticipated to reduce diesel consumption by 0.5 million gallons annually.

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  1. IF NIMBY is not a problem or by off shoring wind turbines could complement the on shore solar PV and the energy storage could tie it all together. Off shoring the wind turbine(s) allows less geo interference with wind flow and also allows one to put these very large, very high 100 meter to 140meter hub height far enough out to sea to hide the wind turbine from the shore. When one gets this high in the air, the winds become more constant and the output from wind generation can be 60% as opposed to solar PV 30 to 35% generation capacity. If wind currents are driven by land mass and ocean cooling from night to day, then the solar PV and wind complement each other and provide the majority of energy required each day.