As Rhode Island’s mounting refuse consumes more land, the state agency that operates the Central Landfill, in Johnston, is looking for other, sustainable methods to process the state’s waste, including controversial practices such as incineration and gasification.

Last month, the Rhode Island Resource Recovery Corporation agreed to pay Gershman, Brickner & Bratton, a Virginia-based consultant, $78,000 to research and provide recommendations on alternatives to landfilling the state’s solid waste.

According to the agreement, the firm will consider 11 methods, including new technologies such as gasification, plasma arc and thermal decomposition, in addition to conventional processes such as incineration, which has been illegal in Rhode Island since 1992.

The ban on burning trash came after several years of community opposition to a proposal to build a huge incinerator at Quonset Point.

The executive director of Resource Recovery, Michael O’Connell, said the landfill’s managers wanted to “start with a clean slate and look at everything” to allow for flexibility and research into new technologies.

O’Connell said the corporation is handling the issue with great care given the enormous consequences of building a facility based on bad technology or contracting with an unreliable manufacturer.

“This is the single most important project we have right now and it has the greatest potential to extend the life of the landfill,” O’Connell said. “We can’t make a mistake but we can’t afford to waste time either.”

In its current state, the landfill is expected to reach capacity in two years.

Resource Recovery’s permit request for a 100-acre expansion — to keep it operating until 2020 — is undergoing review by the Department of Environmental Management, O’Connell said.

Landfill managers have the first draft of the consultant’s report in their hands, but O’Connell would not comment on it, saying it is not conclusive enough to share with the public.

The final draft is scheduled to be completed near the end of next month after input from the Statewide Planning Council, he said.

O’Connell said he has been told a waste-to-energy plant that could process the 1.2-million tons of trash Rhode Island throws into the Central Landfill every year would cost $400 million to $600 million.

Operations that follow this model — often privately financed, owned and operated — make their money by selling energy to the power grid, collecting tipping fees from haulers and recycling certain materials, according to the Waste-to-Energy Research and Technology Council, a group of university, government and industry researchers, engineers and scientists.

Energy generation is mostly an afterthought for the corporation, O’Connell said, with finding a way to handle the increasingly unwieldy mountain of garbage being the priority.

Most waste-to-energy plants operating now are not profitable through the sale of power alone, he said.

Resource Recovery officials visited a gasification plant in LaCrosse, Wis., in June. It differs from the profile of a plant that might serve Rhode Island in three ways: its fuel is 50 percent municipal solid waste and 50 percent wood chips, its primary function is power production and it processes only 80,000 tons of trash a year — or about 15 times less than the annual waste output of Rhode Island.

“There is no scaled-up operation, they are all pilot plants,” OConnell said. “I hope they work, but do we want to be the guinea pig?”

Most new waste-to-energy technologies involve some process of heating waste — often to temperatures greater than 5,000 degrees Celsius — which breaks it down into basic chemical components that can then be separated for various uses.

Gases and steam can be used for power and some processes, such as plasma arc, produces a glassy rock-like substance that proponents say can safely contaminants such as lead and mercury and is stable enough to use as flooring material.

Resource Recovery’s deputy director, Dennis Arusso, who also visited the LaCrosse facility, said the trip was essentially a walk-through of the operation and there was not much discussion about emissions, a top concern of environmentalists.

Eric Suuberg, a professor of chemical engineering at Brown University, said waste-to-energy projects are complicated because of the heterogeneous nature of common trash.

First there is the issue of spending a lot of energy burning off water, then monitoring for a slew of emissions such as dioxin, mercury and lead.

“Because you don’t know what is coming in, you have to be very broad in monitoring what is coming out,” Suuberg said. “That is an engineering challenge.”

State environmental groups have their doubts about waste-to-energy projects and voiced the opposition to proposals like the one brought forth by Jefferson Renewable Energy in 2007.

“None of these [methods] would be a real solution to handle our waste problems,” said Sheila Dormody, the director of Clean Water Action’s Rhode Island affiliate. “For any of the newer technologies we would have to change the law. It seems clear that they are similar enough to incineration.”

Last summer Resource Recovery stopped just short of signing a memorandum of understanding with the Rhode Island-based Jefferson Renewable Energy, to pursue a proposal to build a waste gasification plant.

At the time, neither the company nor O’Connell could provide many details about the technology, which is still largely experimental for large-scale operations.

O’Connell said once the corporation has the consultant’s final report by the end of next month, it will entertain proposals from all interested parties.

If history is any indication, waste-to-energy proposals in the Ocean State may face heavy public scrutiny from environmental groups.

So far, none said they would outright oppose any waste-to-energy proposal, but they all agree that calling municipal garbage “renewable energy” is misleading to the public and dresses up polluting habits as a clean alternative power source.

Generally the groups prefer a reduced-consumption approach and a more aggressive statewide waste management program to ease the stress on the landfill.

The expansion of municipal “pay-as-you-throw” trash collection strategies have boosted recycling in the affected town and cities, such as Central Falls, where the recycling rate jumped 20 percent when residents were charged per bag, said Resource Recovery recycling manager Sarah Kite.

O’Connell concedes that there are still many unanswered questions, but one thing is certain — the problem is going to continue to worsen.

“Whenever we run out of space at the landfill here, get your checkbook out,” he warns. “Because it is going to cost a lot to get rid of your trash.”

ngarcia@projo.com