After years of false starts, a bipartisan group of senators on Wednesday produced a 417-page permitting reform bill, designed to make it easier to build everything from long-distance power lines to renewable energy projects to natural gas pipelines. A vote is not expected until after the midterm elections. That leaves plenty of time to argue over what the sprawling compromise would actually do for the climate: decrease or increase US greenhouse gas emissions?

The answer isn’t obvious.

Faster permitting could unlock clean-energy projects that have been stuck waiting for approvals, while also making it easier to build pipelines and other fossil-fuel infrastructure. Researchers are now starting to put numbers around those competing effects. One new analysis published this week offers a sense of the potential climate payoff from an important piece of the legislation: transmission reform.

Streamlined rules making it faster to connect energy projects to the grid and expand energy connection, or transmission, between regions could cut carbon dioxide emissions by 71 million metric tons, or 9%, in 2035 compared to a non-reform scenario.

The modeling, conducted by the nonprofit Center for Climate and Energy Solutions (C2ES) and consulting company Greenline Insights, does not comprehensively address the bill’s laundry list of proposed reforms. It’s only focused on the transmission piece and on how changes would affect four regions of the country that account for about half of US electricity demand. Despite those limitations, C2ES president Nathaniel Keohane told Bloomberg News he’s confident the bill “on net is good for the economy, it’s good for consumers, and it’s good for climate.”

The estimated impact on power-sector emissions is particularly notable, he added: “We’re talking gigaton-scale emissions reductions over time.”Rob Gramlich, president of the consulting firm Grid Strategies LLC, said that although the package is technology neutral — meaning it doesn’t favor specific types of energy generation — it “enables a clean energy future” that’s “just going to be very hard to get” otherwise. Consider data centers.

One way to power them quickly is to build gas infrastructure on site. “This bill would open up a lot more options,” Gramlich said, adding that there are many states, utilities and technology companies looking to clean up their power supply. Other climate science and policy experts seem to agree.

In a post on X, Jane Flegal, a former Biden administration climate official who is now a senior fellow at the liberal think tank Searchlight Institute, called the bill “awesome.”“Bottom line, I think the bill will likely reduce US greenhouse gas emissions,” said Zeke Hausfather, a climate scientist and energy systems analyst at the nonprofit research group Berkeley Earth. “The main reason is that federal permitting is a much bigger obstacle for clean energy than for fossil fuels today.”

However, he cautioned, the fossil-fuel provisions would take effect immediately, while the biggest clean-energy gains would take much longer to arrive, since they depend on years of implementation by federal regulators.

Environmental activists are less bullish on the deal. They are fearful of the implications for endangered species, waterways and public participation, as well as emissions. Manish Bapna, president of the Natural Resources Defense Council, called the transmission provisions “desperately needed” but said the group is still assessing whether those outweigh changes that could accelerate oil and gas development and thereby limit the legislation’s climate benefits.

Permitting reform has long held bipartisan appeal. But this year, the political stakes of rising power bills and opposition to data centers gave Democrats and Republicans a new impetus to try to ease the crunch on the grid. The deal is far from certain to become law; it could still change significantly or collapse. It is a mixed bag — and, some experts say, probably as ambitious as environmental policy will get under the current administration.