A Japanese energy company has pitched a plan to build a 398-megawatt, natural gas-fired power plant at the site of the decommissioned Shoreham nuclear power plant.

But the proposed plant would use an existing substation that another private energy proposal, an off-shore wind farm called “Deepwater,” would need to use, setting up a decision that could dictate the future of the shuttered nuclear plant site.

The Long Island Power Authority is expected to reach a decision later this year, though LIPA — which had issued a request for proposals for new powers sources — could go with other proposals that have nothing to do with the Shoreham property.

J-Power USA, a subsidiary of a Japanese conglomerate that already runs a “peaker” station at the on-site Long Island Power Authority plant that’s used during power shortages, proposed to build the natural gas plant just west of the nuclear station.

In order to operate the plant, J-Power has proposed extending a natural gas pipeline from the Long Island Sound, according to a nine-page proposal the company has submitted with New York State.

The company is also seeking to expand production at the peaker plant in Shoreham, as well as another one in Edgewood.

“Right now natural gas is the flavor of the day,” said Sid Bail, president of the Wading River Civic Association and a member of a LIPA committee looking into possible uses for the old nuclear facility.

“The advantages of this in terms of the community is increase in tax base,” he added. “Another advantage is what’s lovingly called ‘community benefits.’

“For controversial projects, [the company will sometimes] pay additional funds to fund worthwhile things in the community,” he explained of the community benefits. “That’s kind of what happens.”

Mr. Bail said that noise coming from a new plant would be a concern to locals. LIPA had also claimed to make Shoreham a green energy power station, he said, and noted that gas is a cleaner fuel than oil, but still pollutes the environment.

“The concern side of it, is that LIPA started ‘a new direction’ for Shoreham, green energy for Shoreham,” Mr. Bail said. “[Natural gas] is a fossil fuel. It’s the cleanest of the fossil fuels, but it’s still a fossil fuel.”

Part of that new direction, Mr. Bail said, is an existing proposal called “Deepwater Wind,” which would build a 900-megawatt wind farm about 30 miles east of Montauk in national waters.

The Deepwater wind farm, which company officials said would be spaced out over 200 square miles, would send energy into an existing LIPA substation at the Shoreham site, the same substation that would be in use by the J-Power plant.

Deepwater say the farm could provide a third of Long Island’s power during peak hours thanks to the gusting North Atlantic winds.

The proposal is modeled after successful offshore wind farms in Northern Europe, and over the long term would displace more costly fossil fuels with cheaper, readily available energy, the proposal states.

Construction of the wind farm would begin in 2016, with the first sections of the turbines operational by spring 2017, according to the proposal.

Mr. Bail and members of the Wading River and Shoreham civic groups met with Deepwater’s associates this week.

Both proposals are before the state and LIPA, Mr. Bail said, adding that he was told that LIPA would decide which proposal or proposals it favors late this year.

Deepwater officials said they are hoping LIPA will release a “short list” of about seven energy proposals by the end of September.

A LIPA spokesman declined to comment.

psquire@timesreview.com