Sonoma County's two largest cities appeared headed down divergent energy paths Tuesday, with Santa Rosa vowing to move swiftly toward a decision on whether to join the Sonoma Clean Power Authority the day after Petaluma delayed a decision until at least September.

Santa Rosa City Council members expressed both strong support and deep reservations about the proposal, but all agreed to try hard to make up their minds one way or another by the impending June 30 deadline or shortly thereafter.

"I love the concept. I want it to work, but I've got to make sure it's right for our city, and I'm not there yet," Councilman Jake Ours said.

The council decided to convene its three-member subcommittee in coming weeks to get answers to myriad questions it has about the plan's governance, rates, green energy mix, and impact on greenhouse gas emissions. It proposed another full public hearing on the issue in late June.

Mayor Scott Bartley said the city would "move as fast as we can move," but warned that pressure on it to act quickly was like "pushing on string, and that doesn't work."

The call for quick action follows a unanimous move Monday by the Petaluma City Council to further study the proposal, effectively putting off any decision until after the county's June 30 deadline and possibly until next year. The county's second-largest city joins Cloverdale, its smallest, which also decided to sit on the sidelines for now.

"It may be that there's a better path for Petaluma," Mayor David Glass said Tuesday.

So far, Windsor is the only city to formally join the power agency. Rohnert Park and Sebastopol could join in a second round of hearings next month. Cotati's first presentation in the current series is today, while Sonoma's council takes up the issue June 3.

The creation of a public power agency is intended to supplant PG&E as the county's primary source of electricity and offer a greener energy portfolio, with sources including solar, wind, geothermal, biomass and small hydroelectric projects.

The agency intends to start with power that is 33 percent from renewable sources, a greater proportion than PG&E's 20 percent.

County officials estimate that in 2014, Sonoma Clean Power rates for residential customers would be 1.8 percent lower to 1percent higher than PG&E's, and for commercial customers 3 percent lower to 0.5 percent higher.

It was difficult to read the leanings of many Santa Rosa council members Tuesday. All said they wanted the agency to work, but they also voiced a litany of questions they wanted answered before they could fully support it.

But at least two council members said that if Santa Rosa didn't participate, it wouldn't have a seat at the table of the Joint Powers Authority and therefore couldn't influence the policies that might affect it if it joined later.

"A lot of these decisions have been made without us, and rather than letting more of them be made without us, I'd like to see us hop on that train before it goes by us too much further," Erin Carlstrom said to a round of applause from a chamber packed mostly with supporters.

First District Supervisor Shirlee Zane kicked off the afternoon session with an impassioned plea for political courage. She invoked Monday's horrific tornado in Oklahoma as yet another sign that climate change is happening and local jurisdictions need to take bold action before it's too late.

She stressed that without a seat on the board, the city "will not be able to be a part of sculpting the details of this important and innovative and historic program."

Anticipating the barrage of highly detailed questions that followed, Zane urged council members to remain focused on the bigger picture.

"We need to stop quibbling over 1 or 3 percent rates and remember that this earth will be inherited by our children," Zane said. "This is about leadership. That's what we're here to talk about today, not caution."

She appealed directly to Carlstrom, who is several months pregnant, as an example of someone who should act with the future in mind.

"It's always nice to call out the pregnant lady, because you do reflect our children," Zane said.

But Kathy Millison outlined the complexity of the decision facing the council. She noted that it needs to make a decision not only on behalf of the city's residents, but on behalf of the city budget. In 2012, the city government itself used 40 million kilowatts of energy, costing taxpayers and ratepayers $5.6 million, Millison said. With 791 separate PG&E meters paying 20different rates, figuring out the budget implications for the city is daunting, she said.

Several speakers pointed out that Sonoma County's 70 percent opposition to Proposition 16 in 2010 was a virtual mandate from voters to support the new power authority. Resident Ben Zolno, who worked against the PG&E-backed proposition to require a two-thirds public vote to join so-called Community Choice Aggregation programs, called Santa Rosa's support crucial.

"Without Santa Rosa as part of this, Sonoma Clean Power is either really weak or it's dead," Zolno said.

He stressed that the city's participation would give the fledgling agency significantly more leverage in negotiating contracts with potential power suppliers. Santa Rosa accounts for nearly 35 percent of PG&E-supplied power in Sonoma County.

One of the few critics of the plan was Novato resident Jim Phelps, an engineer who said he opted out of Marin County's power authority and questions its legitimacy.

Phelps singled out the agency's reliance on renewable energy certificates to achieve its 33 percent green power goal. The agency says roughly half of its renewable supply will come from energy credits that some critics say amount to greenwashing, allowing a user to claim renewable sources while actually getting conventional power from the grid.

Phelps held up a plastic cup full of dirty water and likened it to brown power. Then took a white paper receipt, which he said was, in essence, all a renewable energy credit is. He said the claim that such certificates ensure the production of green energy was "patently false." He then wrapped the receipt around the cup and said "Voila! Instant green energy that your constituents will buy, and they won't know it."

He then held the cup up to the council and said: "This is clean water. Who'd like a drink?"

Following the hearing, Cordel Stillman, deputy chief engineer for the county Water Agency and the lead staff member on the proposal, said he was pleased with the support the council members showed and said their numerous questions were easily answerable.

The detail of the questions showed they are on board with the concept, and are now "in the weeds" working out the details, which Stillman said was promising.

Petaluma appears to be much more wary of the county plan.

The city's discussion kicked off Monday with a presentation by Supervisor David Rabbitt, the south county representative and a former Petaluma councilman. Rabbitt, the only county board member to vote against the power plan launch this year, said he had wanted more time to study and develop the plan. Several Petaluma council members echoed him with their own comments.

"There's no urgency because the county already has the go-ahead to meet their capacity in the first year," said Glass, the mayor.

Petaluma council members voiced concern especially about the sway that the county and Santa Rosa — the two biggest power users — would hold on the agency's governing entity, the Sonoma Clean Power Authority.

Councilwoman Teresa Barrett questioned whether the city might partner instead with Marin County's public power program, launched three years ago. The program recently expanded to serve customers in the Contra Costa County city of Richmond.

That possibility and other questions will be the focus of a staff report that is set to take at least three months to compete. Glass was adamant in an interview Tuesday that a closer look was better for Petaluma.

"We're going to continue to investigate our options and explore possibilities," he said, brushing aside questions about possible political blowback from the county and the powerful coalition of business and environmental interests pushing the proposal.

"That's not my worry," he said. "My worry is to get the very best deal for the people of Petaluma, period."

You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @citybeater.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett.wilkison@pressdemocrat.com.