JOHNSTON — A New Jersey company aims to more than double the output of trash-fueled electricity generation at the state’s Central Landfill.

The owner of the long-established methane power facilities at the dump, Ridgewood Renewable Power, hopes to kick off its new energy project, estimated to cost between $65 million and $70 million, this fall.

Ridgewood’s three existing plants at the landfill can produce about 20.5 megawatts of electricity –– enough to power about 15,000 households, according to a Ridgewood vice president, Stephen D. Galowitz.

The proposed project would boost that generation to about 43 megawatts, Galowitz said yesterday, adding that the expansion would make the facility one of the largest of its kind in the United States.

Ridgewood plans to build a new generation facility across the street from the landfill and a separate methane gas treatment facility on nearby land, he said.

The company also envisions enhancements to the vast system of pipes that collect methane wafting from decaying garbage.

Galowitz’s comments yesterday followed his appearance alongside Mayor Joseph M. Polisena at Monday night’s Town Council meeting.

He and Polisena announced that the company will now pay the town $250,000 annually, along with cost-of-living adjustments in lieu of taxes.

Until now, Ridgewood has paid $108,000 a year in lieu of taxes, Polisena said, adding that the company isn’t required to pay taxes for property located on land owned by the Rhode Island Resource Recovery Corporation, the landfill’s overseer.

Electrical generation facilities have been at the state’s landfill since the late 1980s, according to Resource Recovery’s executive director, Michael O’Connell.

The site currently has three different plants.

Two of them must be torn down by the end of next year to allow for the expansion of the dump, according to O’Connell.

The replacement facility for those plants will be located on a 4-acre parcel across Shun Pike, near the entrance to the landfill, Galowitz said.

A separate facility, which will clean the methane before it flows into the new electricity generating plant, will be built on another 2- to 3-acre parcel just north of where Shun Pike meets Green Hill Road, he said.

The new facilities will use a different technology to generate more energy from the methane byproduct of Rhode Island’s trash.

Currently, the methane gas simply powers electricity generators. The process produces great amounts of heat, but the system doesn’t use that heat to produce energy.

The new plant will also use that heat to power generators, Galowitz said.

He emphasized that methane gas plants produce energy at about 90 percent of their capacity.

Certain other types of renewable energy facilities, such as wind turbines, are less productive, he said.

Electricity from the state’s landfill should be available to Rhode Islanders for many years, he said,

If the landfill reaches full capacity in 2022, it would still provide good amounts of methane gas for another 15 years, Galowitz said.

“We know we have a very long-lived asset here that will continue to provide electricity well into the future,” he said.

mreynold@projo.com