PROVIDENCE — It turns out that an 85 percent reduction in greenhouse gas emissions is easier said than done.

A preliminary study commissioned by the Executive Climate Change Coordinating Council (EC4) concludes that even with the near elimination of fossil fuels to generate electricity, heat homes and power cars, Rhode Island will only be able to cut its greenhouse-gas emissions 62 percent by 2050.

Don’t fear, according to the consultants conducting the research. The target will be more attainable with the advancement of new technologies and emission reductions from other sources of greenhouse gases such as landfills, manufacturers, cement plants and off-road vehicles.

“This is a work in progress,” said Taylor Binnington, a scientist with the Stockholm Environment Institute (SEI). “We’re almost there but not quite.”

Somerville, Mass.-based SEI conducted the greenhouse-gas study with Northeast States for Coordinated Air Use Management (NESCAUM) of Boston. The consultants were retained by the EC4 to meet state emission-reduction targets set by the General Assembly when it passed the Resilient Rhode Island Act in 2014.

The study cuts emissions from 10 of the biggest emitters of carbon dioxide, such as power plants, transportation and home heating. The calculations assume that by 2050 the energy grid will be charged with 97 percent renewable; electric vehicles replace 85 percent of gas-powered cars; and 90 percent of homes heat and cool with heat pumps.

The report also postulates the following emission reductions: 80 percent from buses; 95 percent from refuse trucks; 80 percent from tractor-trailers; 100 percent from trains; and a 40 percent fuel-efficiency improvement in the aviation sector.

Other assumptions include a relicensing of the Millstone Nuclear Power Station in Waterford, Conn., and a 31 percent use of biodiesel in diesel-powered vehicles. The report doesn’t contain underlying assumptions about specific sources for future energy generation, because, Miller said, they are revisiting their facts and figures.

Left unanswered are the impacts of the proposed Burrillville power plant, natural-gas pipeline projects and new fossil-fuel infrastructure, such as the proposed liquefied natural gas facility on the city’s waterfront. Questions also remain about the study’s assumption of an increase in high-carbon biomass and imported hydropower.

Groups outside of the state climate council called for greater protection of natural resources that help reduce and store climate emissions.

Paul Roselli of the Burrillville Land Trust and Christopher Riley of the Rhode Island Woodland Partnership spoke of the need to protect carbon sinks such as open space and forestland.

James Boyd of the state Coastal Resource Management Council said by 2050 sea-level rise will likely destroy half of Rhode Island’s remaining wetlands — another valuable carbon sink. Boyd also noted that the state must improve compliance with its Land Use 2025 plan and stop clearing open space for large commercial developments outside of urban centers, such as the new Citizens Bank office park in the Johnston woods.

“That means we shouldn’t be cutting a hundred acres or two hundred acres of forest in chunks because we are going to lose that as a carbon sink,” Boyd said. “So, we’re doing all of the things that our policy says we shouldn’t be doing.”

He repeated the conclusion reached by many at the recent meeting. “The takeaway from today is that if we aggressively do all of these (emissions) reductions we’re still not going to make the 80 percent target,” Boyd said.

Todd Bianco, principal policy associate with the Public Utilities Commission, was surprised that renewable energy alone couldn’t hit the state’s emissions-reduction target. “It’s definitely a surprise that you can go to a nearly 100 percent renewable grid, push a bunch of technologies on to that grid, and fall far short of your target,” he said.

The study is expected to be discussed at the Oct. 12 meeting of the full EC4. A report on the state’s climate plan is due to Gov. Gina Raimondo by the end of the year. The EC4’s subcommittee on greenhouse gases meets next on Nov. 18.

Rhode Island emissions
In 1990, Rhode Island generated 10.74 million metric tons of carbon dioxide. In 2010, the state generated 12.25 million metric tons. The top three emitters in 1990 were highway vehicles (41 percent), residential heating (22 percent) and commercial heating (7 percent). In 2010, the top three greenhouse-gas emitters were highway vehicles (30 percent), electric power generation (26 percent) and residential heating (19 percent).