California’s pitch for 100 percent renewable energy is dead -- for now.

In the last week of its legislative session, California bills that laid out plans for a 100 percent renewable grid by 2045 and a remake of the state’s grid into a regional system foundered.

Legislators’ failure to move the bills through could add fuel to the larger 100 percent renewable energy debate, in which a variety of stakeholders have questioned the speed, pathway, feasibility and, ultimately, the need for converting to 100 percent. The struggle raises an important question: If California can’t make 100 percent a reality, can other large economies?

The downfall of California’s 100 percent renewables bill, SB 100, came shortly after unions representing about 120,000 electric and utility workers, which had previously supported the bill, turned their backs on the legislation amid worries over job loss and grid security.  

“There’s a lot in all the bills that we like,” said Tom Dalzell, business manager at the International Brotherhood of Electrical Workers Local 1245, based outside of Sacramento. “Our interest was protecting the distribution system and the jobs of our members that work on the distribution system.”

Before the Brotherhood came out against the bill, California lawmakers had already shifted the initiative from 100 percent renewables to a "100 percent greenhouse-gas-free" energy goal, with a mandate to reach a lower 60 percent renewables target instead. Even with the added flexibility, SB 100 failed to advance and has been tabled until next year. 

Among the bills that slipped through the cracks this session was a proposal from Assemblymember Chris Holden to revamp California’s grid by regionalizing the authority of the California Independent System Operator (CAISO). The proposal, introduced just last week, was meant to allow California to more easily coordinate transfers of renewable energy across state lines in the West when the state has excess supply or not enough.

Groups like Dalzell’s worry that changes to the grid could mean fewer jobs. Many groups, like the Sierra Club and the Utility Reform Network, also joined unions in expressing concern that regionalizing CAISO would loosen California’s grip on its grid. Environmentalists were especially concerned that it may allow other states to send coal- and natural-gas-fired power to the state. Governor Jerry Brown supported Holden’s plan.

The complications that brought down the 100 percent bill in the eleventh hour are demonstrative of larger questions swirling around the possibility of a 100% renewable energy scenario.

Many cities have already committed to all renewables. Hawaii has approved the same goal California was considering -- 100 renewables by 2045 -- and has plans to get there early. But the state consumes much less energy and has a smaller footprint.

In May, questions about how an economy as large as the entire United States can get to 100 percent renewables became the source of an unusually heated academic debate when colleagues called out the research of Mark Jacobson, a Stanford professor who argued that reaching full renewables is entirely feasible with a World War II-style mobilization of mostly wind and solar. 

“Policymakers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power,” wrote the authors of a paper rebutting Jacobson’s findings.  

The academic debate broke out as state Senate President Pro Tem Kevin de León sought to advance SB 100, making a big splash over California’s renewable ambitions.

For now, the debate over 100 percent renewable energy wages on. And though the delay on the energy bills does look like a setback, environmentalists say they’re not fretting. “We’re going to be back next year,” said Peter Miller, Western energy project director at the Natural Resources Defense Council. 

“I don’t want to underestimate the challenges to moving to a fully zero-carbon grid, but we can get there, and we will," he said. "It’s going to take some time.”

Back in California’s capital, it wasn’t all letdowns for clean energy advocates in the last week of the session. On Thursday, the legislature did pass Assembly Bill 797, an extension on incentives for solar thermal technologies that have offset 31,000 metric tons of carbon dioxide a year. That bill now heads to Governor Brown’s desk.