Tourists visit Hawaii for the sun and sea. Now, solar and reservoir water could be central to the way the state’s only electric co-op produces electricity well into the next century.

"We want to pump water from the Mana Reservoir to the Puu Opae Reservoir using solar power, and release the water to generate electricity for our members," said David Bissell, CEO of Kauai Island Utility Cooperative.

The project is part of an overall plan to revitalize agriculture and restore habitat on the western side of Kauai Island. Restoration and maintenance of the reservoirs and associated infrastructure are key to this effort.

The Lihue-based co-op will spend up to $350,000 on preliminary survey, engineering and permitting work for the pumped-storage project. It could eventually produce about 25 megawatts of hydroelectric power, or enough to meet about 15 percent of the island's electricity needs.

Plans include a five-mile pipeline to move the water between the two reservoirs and an 8-kw solar array to power pumps that will move the water uphill during the day. Release of the water through turbines at a power house would help meet co-op demand when its other generation facilities are not producing adequate power.

"We see the Puu Opae pumped-storage project as an investment in the co-op's future that could still be providing energy 100 years from now," said Bissell. "It will help ensure energy and water resources for our members, and get us closer to our goal of meeting 70 percent of our energy demand with renewable resources by 2030."

The co-op has worked closely with the Department of Hawaiian Home Lands, the state's Agribusiness Development Corporation and local organizations to develop sustainable projects. If the pumped generation project is built, KIUC has agreed to support several initiatives designed to improve and maintain reservoirs, existing streams and drainage serving the area.

The overall project could cost up to $90 million and construction could begin in 2020, co-op officials said.