Oahu is on its way to joining Maui and the Big Island in the effort to harness the state’s famous tradewinds.

Today developers will break ground on a wind farm in the hills near Kahuku.

The 30-megawatt project on the North Shore is the first large-scale commercial wind farm on the island and includes several technological advances, such as a battery system that will help smooth out the stability of the electrical load.

The project is being built by Kahuku Wind Power LLC, a unit of Newton, Mass.-based First Wind. The wind farm will feature a dozen state-of-the-art Clipper Liberty wind turbines with a maximum output of 2.5 megawatts each. Based on expected wind speeds at the site, the system will generate an estimated 83 million kilowatt-hours annually, the equivalent of 139,500 barrels of oil.

That’s enough electricity to power 7,700 homes for a year, according to the company. The wind farm is targeted for completion early next year.

The turbines will be set up on about 575 acres, most of which is owned by First Wind. The three-blade turbines will sit on steel towers 260 feet high, with turbine blades reaching a maximum of 460 feet at their peak.

The electricity will be sold to Hawaiian Electric Co. under a purchase power agreement approved by the Public Utilities Commission in May.

While the 30-megawatt output is a small part of HECO’s islandwide generating capacity of 1,700 megawatts, it is part of the incremental move toward decreasing the state’s dependence on oil. About 90 percent of the state’s energy usage comes from imported petroleum.

"It’s not a huge amount of capacity, but it’s very valuable because oil prices are expected to continue going up," said Peter Rosegg, HECO spokesman.

One of the benefits of the system is that the electricity generated by the wind turbines at night can be used to charge electric vehicles as the state moves in that direction, Rosegg added.