A federal mandate for states to obtain a set portion of electricity from renewable energy is a forgotten aspect of climate change policies, but some Democrats say it belongs back on the table.

These Democrats are uneasy with the lofty goals set out in the Green New Deal resolution backed by Rep. Alexandria Ocasio-Cortez (D-N.Y.) that calls for a 10-year “mobilization” to meet 100 percent of U.S. power demands with “clean, renewable, and zero-emission sources.” They say a more modest target is achievable.

Sen. Tom Udall (D-N.M.), who along with a half-dozen other Democrats has backed legislation directing utilities to get about 30 percent of electricity from renewable sources by 2030, “is working on an updated standard to be introduced this Congress,” Udall spokesman Ned Adriance said in an email.

In the House, Rep. Peter Welch (D-Vt.), a senior Democrat on the House Energy and Commerce Committee, also told Bloomberg Environment that he plans to roll out legislation in the coming months requiring utilities to meet a federal goal for drawing from solar, wind, geothermal, and other renewable energy sources.

Under Welch’s 2017 American Renewable Energy and Efficiency Act (H.R. 2746), utilities would have to gradually increase their use of renewable energy to roughly one-third of their total power output over the next two decades. Welch is considering strengthening his bill’s mandate.

“Probably my bias is toward making it more ambitious,” he said. “Our goal in drafting this is to do something that would have a measurable impact on emissions.”

Republicans Disfavor Top-Down Policy

Congressional efforts to force states to get a base level of electricity from wind, solar, and other clean energy appeared to gain momentum during the George W. Bush administration.

The House tucked such a mandate, known as a renewable electricity standard or renewable portfolio standard, into the House-passed cap-and-trade bill in 2009 directing states to get 20 percent of electricity from clean energy by 2020. The bill died in the Senate.

States have stepped into the void.

Twenty-nine states, Washington, D.C. and three territories have such standards today, according to a February report from the National Conference of State Legislatures. Most require between 10 percent and 45 percent renewable energy, but seven states and Washington, D.C., have renewable requirements of 50 percent or greater.

A decade later, states have driven much of the progress. Roughly half of all growth in U.S. renewable electricity generation and capacity since 2000 is associated with such state requirements, according to a 2018 Lawrence Berkeley National Laboratory report.

‘Don’t Want to Force States’

Congressional Republicans say such top-down requirements should be avoided and stay in states’ hands.

“You know, that’s tough for Republicans because we’re federalists, and we don’t want to force states” to adhere to a single federal standard, said Rep. John Shimkus (Ill.), the top Republican on Energy and Commerce’s Environment and Climate Change Subcommittee, told Bloomberg Environment.

Senate Republicans such as Sen. Rob Portman (R-Ohio) agreed that states can best decide their own goals or targets for renewable sources, adding that some are better able to take advantage of some sources than others.

“There’s an argument for each state working out what is right for them, because every state is different on weather and even topography and fuel mix,” Portman said. “If you’re in Nevada or Arizona, solar makes all the sense in the world. If you are in a windy state, like Indiana or even parts of Ohio, wind might make more sense.”

Given Republicans’ 53-seat Senate majority, the Democratic bills face an uphill battle in that chamber.

Alex Flint, a former Republican staff director for the Senate Energy and Natural Resources Committee, said he’s skeptical one federal standard could work with a power sector that has become an increasingly complex web of generators and distributors.

“We have so many market structures out there, it’s very hard to imagine one overlay over the entire generation and distribution system,” said Flint, who heads the Alliance for Market Solutions, which is pushing Republicans to embrace a carbon tax.

All Tools on the Table?

But some climate advocates, such as Sen. Bernie Sanders (I-Vt.), now in a crowded race to become the 2020 Democratic presidential nominee, say action is needed given increasingly dire warnings of climate change.

This includes a 2018 Intergovernmental Panel on Climate Change report that warned the world has only a dozen years to act to avert increasingly severe climate impacts.

“I think you are going to have to look at all the tools that are available to transform our energy system and substantially reduce carbon emissions,” Sanders said.

Rep. Paul Tonko (D-N.Y.), who chairs the House Energy’s Environment and Climate Change subcommittee, said “all options should be on the table,” including a renewable mandate, although he’s not ready to back specific policies yet.

More than 80 House Democrats support the Ocasio-Cortez resolution, including several chairmen. But neither Tonko nor Energy and Commerce Chairman Frank Pallone (D-N.J.) is among them.

Energy and Commerce will take a methodical approach “to get a real strong statement made about carbon pollution reduction,” Tonko said.