CARLSBAD -- With avid encouragement from some audience members, state Energy Commission staffers sought more information Wednesday on air quality concerns related to a power plant that was proposed near Agua Hedionda Lagoon.

State staff members wanted to know what might happen to the Carlsbad plant's emission rates if the plant is quickly fired up to meet extreme power needs. They also wanted more details about how the initial start-up phase of the plant will be handled, among other things.

One state air quality official said some of the issues they were raising were "technical points that I think can be solved."

Others said the power plant's developer, NRG Energy Inc., had recently submitted new information that would require extra air quality analysis. NRG officials disagreed with this assessment, saying they thought paperwork they had recently provided simply reiterated existing information.

Wednesday's all-day meeting was the first of a two-day workshop session that covers issues raised in the state's new draft assessment of the project.

Information gathered at this week's event and in paperwork submitted in the weeks to come will be incorporated into a final report. State commissioners will use that report when they vote on the project, and their vote is expected later this year.

NRG Energy Inc., which owns the 95-acre Encina Power Station property along the lagoon, has proposed to add two sets of electricity-generating equipment on the far eastern end of its property between the railroad tracks and Interstate 5.

The new equipment would be capable of producing 558 megawatts of electricity, or enough to power roughly 400,000 homes.

Plans call for the equipment, and a second project later, to allow the demolition of the aging power plant now on the western end of the Encina site.

Air quality concerns have been one of several key issues opponents have raised since the project was proposed in fall 2007. Other hot topics have been the proposed plant's industrial look and its closeness to the freeway and the lagoon.

Starting at 11 a.m. Thursday, commission staff will tackle transportation and visual issues. The sessions, open to the public, are held in a conference room at the new Sheraton Carlsbad off Cannon Road.

The air quality session drew about 100 people, and 25 of them gave public testimony on the plans. The majority of the speakers -- 19 in all -- opposed the proposal.

The speakers included a Carlsbad planning commissioner involved with a citizens' group called The Power of Vision Carlsbad; a wife of a city councilman; and many people who live close to the Encina Power Station.

They said it was time for Carlsbad's prime coastline to stop playing host to an industrial operation like a power plant, and they repeatedly raised health concerns related to plant emissions. Several invited commission staffers to their homes to see the black grime they say drifts from the power plant onto their yards and into their homes.

"We're talking about putting in an air filter," said Phyllis Hall, wife of Councilman Matt Hall.

Carlsbad resident Cathy Fredinburg said she wanted much more information about the pollutants that the proposed plant would emit and whether its emission rates would be worse than the existing power equipment on the Encina site.

Senior air quality analyst Keith Golden responded that the state's review of the plans indicates that some pollutant levels will increase, while others will drop.

Fredinburg then asked what the percentage increase was for the ones that were going up. Staff members said that wasn't easy to calculate.

Not everyone who lives near the project site was opposed to the proposal. Some said the region was already industrial-looking, and the new equipment would eventually allow Encina to tear down the huge, aging power plant now on the property.

"If there's a better place to put the power plant, we should have heard about it by now," said Carlsbad resident Jeff Lynch, referring to the city of Carlsbad's recent exploration of alternative power plant sites.

Meanwhile, commission staff said they wanted Encina's owners to submit more information about how quickly they propose to stop using the old equipment.

Under NRG's proposal, three of the five generators within the existing plant would be shut down once the new plant is in place. Commission staff wanted to know exactly when that would happen.

Contact staff writer Barbara Henry at (760) 901-4072 or bhenry@nctimes.com.