A proposal to connect the electrical grids of Maui and Oahu with an undersea cable would save utility ratepayers on both islands an average of 0.6 cents a kilowatt-hour over the life of the project by increasing the amount of renewable energy that could be tapped and allowing the two grids to operate more efficiently, a state official said Tuesday night at a state Public Utilities Commission meeting.

Although the cable would cost an estimated $700 million to construct, it would result in a net savings to ratepayers of $423 million over the 30-year life of the project, state Energy Administrator Mark Glick said in a presentation at the meeting called by the PUC. About 80 people turned out for the hourlong meeting at Farrington High School.

The PUC is gathering public comment as part of its investigation into whether an undersea cable between Oahu and Maui is in the public interest. The PUC has scheduled a similar meeting on Maui for Thursday.

Glick was one of eight people who testified at the meeting, including several who said they had reservations about the project.

Molokai resident Larry Tool said he was concerned that connecting the Oahu and Maui grids with a cable would make it easier for a developer to one day build a wind energy project on Molo­kai to provide power to Oahu. Two energy developers tried and failed in the past to win community support for wind projects on Molo­kai.

"Developers just see the land as a raw material. They just see it as a project on the drawing board. They don’t see the impact on people, the history and the culture," Tool said.

The proposed cable would allow a two-way flow of power between Oahu and Maui from both renewable and traditional sources of energy. The Department of Business, Economic Development and Tourism has said that it sees the cable as the first step in eventually interconnecting all the islands to create a statewide electrical grid.

In a separate proceeding, the PUC is reviewing a controversial proposal by Castle & Cooke Properties to develop a 200-megawatt utility-scale wind energy project on Lanai that would transmit power to Oahu via an undersea cable.

Castle & Cooke executive Chris Lovvorn said the company supported the Maui-Oahu grid-connecting project on the condition that it would include all of Maui County, including Lanai.

"Hawaiian Electric Co. has said it needs a total of 700 megawatts of renewable energy to meet its target of generating 40 percent of its electricity with renewable sources by 2030," Lovvorn said. "To meet the 700 megawatts, they would need all the wind from Lanai and Maui," he said.