Winds blowing across the hills of the Big Island of Hawaii and water flowing through Brighton Dam on the border between Montgomery and Howard counties may not seem to have much in common. But a 4-year-old Washington consulting firm hopes to play a role in harnessing energy from these two natural forces.

The Synetics Group (TSG) this month announced it had joined Control Data Corp., the Minneapolis-based computer and financial services giant, and William Rassman, a Hawaiian wind-energy developer. The group plans to form Renewable Energy Ventures and set up "wind-energy parks" in Hawaii, California and, perhaps, Alaska and the Third World.

Separately, Synetics Group is assisting another relatively new local outfit, Alternative Energy Associates (AEA), of Gaithersburg, to revive Brighton Dam as a hydroelectric power generator, said Michael Lotker, a Synetics partner and vice president.

Synetics is a 25-person consulting company with offices at 1130 17th St. NW. Headed by President Joel Rosenblatt, the firm does energy, environment and economic consulting.

Built in 1943 on the Patuxent River 15 miles upstream from Laurel to store water in the Tridelphia Reservoir and regulate the supply of water downstream to the Rocky Gorge Reservoir, Brighton Dam still houses two turbine generators.

The hydroelectric power plant was taken out of service in 1969 after 19 years of use.

At a projected cost of $750,000 to $1 million, AEA plans to install either a single generator rated at 400 to 500 kilowatts or two units, each half as powerful.

AEA, whose sole general partner is James A. Federline Jr., an industrial builder and mechanical contractor in Gaithersburg, will own and operate the project. In addition, principals from TSG and Renewable Energy Ventures (REV) and other individuals will hold limited partnerships.

AEA is presently threading its way through the bureaucratic process in Maryland for permits to construct the hydroelectric generators. Physical alterations required on the existing dam structure would be minor, AEA says.

The plan is to lease the right to use the dam from the Washington Suburban Sanitary Commission and sell the electricity from the turbines to Baltimore Gas and Electric Co. No final contracts have been signed, but AEA says agreements in principle have aleady been reached with BG&E and WSSC, which will continue to own the dam and could override power operations to fulfill its water-supply responsibilities.

How much Alternative Energy Associates will pay to use the dam and how much it will be paid for the power by BG&E has not yet been determined.

According to TSG, which is providing certain financial advice and coordinating federal licensing, the 995-foot-long, 80-foot-high dam will generate nearly 2.7 million kilowatt hours yearly.

The power plant would be operated at maximum capacity when electric demand is highest. Yearly energy savings have been estimated to be equivalent to about 4,500 barrels of oil, a small amount by itself but significant when combined with the hundreds of other small hydro projects being planned around the country.

AEA currently is trying to arrange financing for the project. TSG notes that possible sources of debt financing include private banks, particularly those specializing in small hydroelectric development such as Boston-based New England Merchants National Bank. Another potential source of funding is the Maryland Energy Finance Administration, a division of the state's Department of Economic and Community Development that makes low-interest loans for energy projects.

The Mid-Atlantic states generally are considered poor locations for windpower projects, Synetics Group executives say, but 4,500 miles west of Brighton Dam are the first of what REV hopes will be scores of windmill installations in Hawaii, California and other blustery areas with sufficient wind.

"Our goals really are to do lots of wind farms," says Lotker, who moved his family to Honolulu recently to open REV's Hawaii office.

The group hopes to install several thousand wind turbines in the next three years before the 15 percent business energy investment tax credit is set to expire, Lotker said. A major lobbying effort is being marshaled to extend the credits to 1990 and expand them to 30 percent.

The Hawaiian wind farm is a joint ventuer of Synetics, Control Data--which holds a controlling interest in Jacobs Wind Electric Co., one of America's oldest windmill producers--and a Hawaiian Jacobs windmill distributor.

Jacobs windmills with 26-foot diameter blades that are capable of producing 17 1/2 kilowatts of power will be used for the first installation, Lotker said. Later jobs may use larger machines by other manufacturers rated up to 200 kilowatts. Lotker said bigger windmills will make it possible to set up ventures that are profitable without the tax subsidies.

Lotker said his company is also investigating the prospects for wind development in Alaska and in Third World countries.

Technical troubles and exotic tax-shelter financing plans have drawn criticism to some California wind developers, but Lotker says REV "will take a very conservative approach" in both technical and tax considerations.

Changes in the tax laws enacted in the last two years offer new opportunities for developers of renewable energy projects, he said, but they also impose tougher penalties on abusive tax shelters.

Lotker said the West Coast ventures are likely to be financed by limited partnerships, a common tax-shelter device which allows investors to write-off directly the cost of the venture.

"We're trying to be creative and to address the new realities of the market," Lotker explained. "You know, this is often called innovative financing, but there is nothing innovative about it. Limited partnerships have been used to finance buildings, box cars, oil drilling rigs, helicopters . . . "

Allan L. Frank is editor of the weekly newsletter Solar Energy Intelligence Report, published here by Business Publishers Inc.