Conservative think tanks in New England are taking aim at state energy policies that promote zero-carbon energy to cut greenhouse gas emissions.

“The Staggering Costs of New England’s Green Energy Policies,” a report released Tuesday by the Denver-based organization Always On Energy Research, and signed onto by free-market advocacy groups in New England, says ratepayers’ bills will double, to $4,610 by 2050, as a result of state policies, or “mandates,” to promote green energy.

Decarbonization plans calling for construction of offshore and onshore wind, solar arrays, battery storage and transmission projects will cost hundreds of billions of dollars over the next 26 years, the report says. The authors of the study say their analysis does not include a calculation of cost savings in New Hampshire for continued use of natural gas.

Environmental advocates blasted the report, calling it inaccurate and misleading. The Acadia Center, a climate and clean energy advocacy group, said the report “overlooks enormous costs borne by ratepayers under today’s fossil grid.”

The report, backed by conservative think tanks, including the Maine Policy Institute, says more than doubling the amount of power from renewable energy cited in an October study by ISO-New England, the region’s grid operator, would provide electricity more reliably, but would be cost prohibitive. It said it would cost New England ratepayers $815 billion through 2050, excluding the impact of federal subsidies.

The ISO-New England report said the region will need 97 gigawatts of renewable capacity — offshore and onshore wind, solar and battery storage — by 2050 to achieve state emissions reduction goals. The report by Always On Energy Research says 97 GW would put the grid at risk for “extraordinarily long blackouts” of about 18 hours. Choosing a “more reliable” 225 GW option is likely to be too costly, it said.

The Always On Energy Research report recommended that states put affordability and reliability of electricity ahead of reducing greenhouse gas emissions. “If emissions reduction goals cannot be reduced without compromising affordability and/or reliability of electricity, they should be abandoned,” it said.

It urged states to lift nuclear moratoriums and other “impediments” to building nuclear power plants that it says will be the most reliable and affordable way to decarbonize the New England grid. Minority Republicans in the Maine Legislature proposed a measure last year directing the state Public Utilities Commission to seek “informational bids” about siting small modular reactors, also known as SMRs and advanced nuclear. The legislation failed to advance.

Electricity prices in New England have increased by more than one-third since 2020, according to the U.S. Energy Information Administration. The average retail price rose to 28.73 cents a kilowatt-hour last year from 21.25 cents in 2020. Numerous reasons include the price of natural gas, which is a main resource used by generators, gas pipeline constraints such as limited capacity and state clean energy policies.

The Acadia Center acknowledged the costs of shifting to zero-carbon energy. “Let’s be candid: There will be significant costs from the energy transition (and significant benefits as well),” it said.

But economic growth as carbon emissions decline “belies the canard that New England state climate policies spell doom for the regional economy,” the Acadia Center said.

The report “ignores the impossibly high cost of business-as-usual,” it said. New Englanders withdraw billions of dollars from the region’s economy each year to purchase fossil fuels sourced outside New England. Vermont, New Hampshire and Maine spend $8.2 billion annually importing fossil fuels, the Acadia Center said.

In addition, the cost of ignoring climate-driven storms, heat waves, flooding and other disasters is the loss of human life and billions of dollars in property damage, it said.

Emily K. Green, acting vice president of the Conservation Law Foundation Maine called the report “unscientific and wildly inaccurate.”

“It is also at odds with the Maine Governor’s Energy Office findings that a clean energy pathway can result in overall energy supply costs remaining generally stable,” she said.

The report and the pushback it drew have put a spotlight on the link between politics and energy policy. The report was released two weeks after President-elect Donald Trump won back the White House and Republicans secured majorities in the U.S. House and Senate. The GOP has promised to reverse much of President Biden’s zero-carbon energy policies.

“As we just saw in recent election results, Americans very clearly said that they are tired of governments coming to them and asking for more and more and more,” Ross Connolly, Northeast regional director for Americans for Prosperity Foundation, said on a conference call as the report was released.

“Ultimately, the voters sent a very clear message two weeks ago that they wanted economic pragmatism over ideology,” said Greg Moore, state director of Americans for Prosperity Foundation in New Hampshire.