NORTH KINGSTOWN — Deepwater Wind LLC’s proposal to build an offshore wind farm off Rhode Island has taken another step forward with the signing of a letter of intent to lease 117 acres in the Quonset Business Park to use as a staging area for the $1.5-billion project.

Steven J. King, managing director of the Quonset Development Corporation, announced the signing at a meeting of the state agency’s board of directors Monday evening. The board is expected to consider on June 29 approval of 10-year leases on three parcels in the business park that Deepwater would use to assemble the more than 100 turbines it plans to install in state and federal waters off the coast.

The news came on the night that Deepwater gave its first formal presentation to the QDC board on the project. Company executives told the board that the parcels, two inland and one waterfront, are crucial to the success of the plan, which includes the installation of five to eight turbines three miles from Block Island by 2012 and the eventual development of a much larger 100-turbine wind farm at least 15 miles from land.

“Quonset, from a strategic point of view, is very important,” said Bill Wall, company vice president of marine construction and operations.

Governor Carcieri and other state leaders envision Quonset becoming the hub of an offshore wind industry on the East Coast. Deepwater’s project, they say, could attract manufacturers of turbine components that would supply offshore wind farms proposed for other Atlantic Coast states.

Deepwater has already submitted a proposal in New Jersey and is looking at New York, too. When board member Barbara Jackson asked Deepwater managing director Jim Lanard if New Jersey has a suitable alternative to Quonset, he said, “There isn’t one.”

Lanard told the QDC board that his company envisions using Quonset to stage projects for New Jersey and New York along with Rhode Island, sustaining an alternative-energy industry in the business park for years.

“We think Quonset is so well situated it can serve all three of those states,” he said. “I think you’re looking at a very long-term proposition.”

Deepwater’s plan in Rhode Island has been progressing on other fronts.

On Monday, Deepwater will open a Providence office at 56 Exchange Terrace where chief development officer Paul Rich will be based. The company also plans to open an office in New Shoreham later this month.

Additionally, within the next four weeks, Deepwater will erect a 180-foot temporary meteorological tower on Block Island that will be used to collect data on wind direction, speed and frequency — information critical to determining sites for the turbines and securing financing to install them. In March, the New Shoreham Town Council unanimously approved the installation of the steel tower at the entrance to the Great Salt Pond, on the west side of the island.

The company has already installed other equipment to aid in its studies, including a radar unit near the Southeast Light to monitor bird migration routes and a bat-monitoring system on a communications tower owned by the Town of New Shoreham. The U.S. Department of Energy has awarded Deepwater a $295,360-grant to finance those studies, which will cost a total of $1.2 million.

akuffner@projo.com