This legislative session is no different. Several GOP-backed bills being considered would loosen restrictions, a possibility that has drawn criticism from Gov. Jay Inslee and opponents who say it would undercut the law aimed at spurring clean energy sources and reducing pollution.
The measures "actually reduce the effectiveness of our renewable energy standard and take us backward on energy rather than forward," Inslee said at a news conference last week.
The Energy Independence Act, which state voters passed as Initiative 937 in 2006, requires nearly a third of the state's utilities, those with at least 25,000 customers, to ramp up and get 15 percent of power from wind, solar, geothermal and certain woody biomass by 2020.
All 17 utilities that must follow the law met the first deadline in 2012 by getting 3 percent of their electricity from renewable energy sources or buying equivalent credits. The companies also met or exceeded energy conservation targets required by the law.
But some lawmakers, utility companies and others say the law creates undue burdens for utilities and raises electricity rates on consumers.
"Every year we don't amend 937, the market become more distorted. Customers are starting to feel the pinch," said state Sen. Doug Ericksen, R-Ferndale, head of the Senate Energy, Environment & Telecommunications committee.
Many utilities have enough power to meet consumer needs, but are forced to sell their cheap power to buy more expensive renewable power to comply with the law, said Ericksen, who has sponsored several 937-related bills.
One of the more controversial bills, Senate Bill 5431, would allow hydroelectric power to be counted as a renewable energy source; that bill hasn't been heard in committee yet.
Since most utilities in Washington already get the bulk of power from hydroelectric dams, it would essentially gut the law. The law excluded hydropower because backers wanted to spur development of new energy sources.
At a committee hearing Tuesday, Grays Harbor Public Utility District and others testified in support of Senate Bill 5648 that would allow utilities to bank energy they conserve above their targets and apply it to future conservation targets. It also says utilities that have enough power would not have to meet a 937 target.
"What's happening is that utilities are having to purchase credits that they can't even use to the tune of millions of dollars," said Sen. Sharon Brown, R-Kennewick, sponsor of SB5648, who referred to her bill as the "no buy before need."
Environmental groups oppose the bill, saying it would undermine the law. They say 937 has created jobs, brought billions of dollars in clean-energy investments, and stimulated local economies.
Changing the law would impact the "fundamental goals of the law, which is to stimulate the market for new development of renewable energy," said Nancy Hirsch, policy director for the NW Energy Coalition, which helped write 937.
Some utilities, such as Puget Sound Energy and Avista Corp., did not support the bill, noting they would be at a disadvantage because they already made long-term investments in wind and other renewable projects to comply with the law.
Business owners and others told lawmakers Tuesday that 937 has resulted in higher rates for consumers and created burdens for businesses.
"It can be argued that these are investments in the future, but the future doesn't do much good for someone who can't pay their electric bill today," said Tim Boyd with Industrial Customers of Northwest Utilities.
But 937 supporters pointed out that a multitude of factors contribute to rate increases.
Another bill heard Tuesday, Senate Bill 5438, allows utilities that conserve more electricity than required by law to bank that excess and apply it toward meeting future targets. Officials from utilities such as Seattle City Light, Tacoma Power and Cowlitz Public Utility District spoke in favor of it.