The state has identified four potential routes for an undersea electrical cable that could deliver energy generated by wind farms on Moloka'i and Läna'i to homes and businesses on O'ahu.

The state Department of Business, Economic Development and Tourism also said it has narrowed its estimates for the costs of the undersea cable to $800 million and $1 billion.

The state previously said the cable's cost could range from between $500 million and $2 billion.

A $1.5 million report conducted for DBEDT by the University of Hawai'i concluded that the undersea power cable project is feasible, despite environmental and engineering challenges.

"This is a huge first step," said Josh Strickler, facilitator of DBEDT's renewable energy programs. "Before we didn't know this was physically possible."

As part of the Hawai'i Clean Energy Initiative, Gov. Linda Lingle's administration last year unveiled plans to build the cable connecting O'ahu to two 200-megawatt wind farm s planned for Moloka'i and Läna'i.

The 400 megawatts could provide up to one-third of Honolulu's power needs and would play a key role in the Lingle administration's plan to reduce the state's dependence on fossil fuels.

The cable study, conducted by the UH School of Ocean and Earth Science and Technology, relied on extensive ocean mapping and geological studies to come up with its recommendations for the four potential cable routes.

The routes included a Läna'i to Pearl Harbor route; a cable connecting Moloka'i, Läna'i and Maui; an O'ahu, Moloka'i and Läna'i cable; and a Käne'ohe to Moloka'i line.

Initially, DBEDT and UH researchers looked at nine potential courses but narrowed the choices based on distance, cost, proximity to existing undersea telecomm-unications cables and potential impact on wildlife and the environment.

Two of the routes run close to whale sanctuaries.

Strickler said the state plans to use the cable report as a basis to develop an environmental impact statement for the project. Many of the impacts on wildlife and environment will be addressed by an EIS.

Strickler added that the state recently narrowed its cost estimates to the $800 million- to $1 billion-range after studying other underwater power cables and by talking to a number of cable manufacturers.

"This project is definitely doable," he said.