An energy co-op on Kauai, Hawaii, is planning an ambitious new project which could provide 15% of the island’s energy needs for the next 100 years.

The board of Kauai Island Utility Co-operative (KIUC) has approved land lease and other agreements for a scheme on the west side of the island, incorporating photovoltaic (PV) and pumped storage hydro technology.

The co-op made the agreements with two state agencies: the Department of Hawaiian Homelands (DHHL) and the Agribusiness Development Corporation (ADC), and the board has approved expenditures of up to $350,000 for preliminary surveying, engineering and permitting work.

KIUC has already started work on required diversion modifications and installation of gauging equipment.

A framework for the project was facilitated via a landmark settlement agreement, approved by the Commission on Water Resources Management in April 2017, which sought to restore appropriate stream flow in the Waimea River, while providing water for other needs such as renewable energy and agriculture.

Parties to the agreement included KIUC, DHHL, ADC, the community-based group Pō‘ai Wai Ola and the Kekaha Agriculture Association.

If the project completes development and is constructed, KIUC will invest millions of dollars in infrastructure improvements and ongoing maintenance on lands owned by state agencies.

Improvements include the rehabilitation of the Puʻu ʻŌpae, Mānā and Puʻu Lua reservoirs, the repair and maintenance of the Kokeʻe Ditch system, the installation of a pressurised pipeline delivering Kokeʻe water to DHHL mauka lands and the Mānā plains, and improved roads.

“This partnership enables the state to provide proper stewardship for the river, while expanding agriculture, energy production and residential development on the west side,” said KIUC chair Allan Smith.

Once completed, the pumped storage hydro project will generate up to 25 megawatts of electricity, and will substantially reduce the utility’s carbon footprint by displacing 5 million gallons of diesel annually.

KIUC says energy will be generated at a cost per kilowatt hour that is comparable to KIUC’s other renewable projects and lower than the current cost of diesel.