Hybrid solar-pumped hydro system planned in Hawaii


Kauai Island Utility Cooperative (KIUC) and AES Corporation are planning to develop a solar powered pumped storage project.

West Kauai Energy Project (WKEP) is aimed to integrate renewable energy and irrigation. It will provide renewable energy production via hydropower and solar PV, coupled with pumped hydropower and battery energy storage to shift most of the project’s output into the nighttime peak. In addition, irrigation water will be delivered to support diversified agriculture on state-owned lands.

The novel project, for which a power purchase agreement has been filed with the Hawaii Public Utilities Commission, also will rehabilitate three existing reservoirs and the related ditch system infrastructure as well as restore flow to the island’s main Waimea River.

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“This project’s integration of pump storage hydropower with large-scale solar power is unique in the energy industry,” states David Bissell, KIUC’s President and Chief Executive Officer.

“Working with AES helps keep this important project moving forward while minimizing risk to our cooperative. Upon completion, the facility will operate at a cost that will benefit KIUC’s members for decades.”

When operational, the solar array will contribute up to 35MW directly to the grid and will store up to 240MWh for dispatch during evening peak. The hydro resources are expected to produce 24MW on average daily, which includes 12 hours of storage to be used overnight.

The project, the third renewable collaboration between KIUC and AES, is up for regulatory approval. With the go ahead, it should move Kauai’s renewable generation beyond 80% and meet more than 25% of its electricity needs, as well as open up dormant agricultural lands for production and increase public access and recreational opportunities.

The long duration storage capacity should enable the island to run on 100% renewable energy for prolonged periods without sunlight. Additional grid stability will be provided by balancing intermittent solar with firm hydropower.

KIUC serves 34,000 customers on the island of Kauai.