Biomass: The Cure for Smokey Lake Tahoe

Last week Placer County, in north-central California, took a big step in its efforts to improve air quality in the Lake Tahoe region. After more than seven years of research -- exhaustive studies by the county, the U.S. Forest Service, and the Placer County Air Pollution Control District, as well as input from residents and other stakeholders on both sides of the California-Nevada border -- Placer County agreed to become the location for a new biomass gasification plant. The plant, which would be run by a subsidiary of San Francisco-based Phoenix Energy, would be located outside of Truckee, Calif., on the north end of Lake Tahoe.

Air quality is a chronic issue in California’s scenic Lake Tahoe area, which sits some two hours above Sacramento in the Sierra Nevada Mountains. At 6,200 feet above sea level, the alpine-enclosed lake becomes a natural catch basin for drifting smoke from wood-burning and auto emissions. These emissions contribute to the degradation of the lake and surrounding forest, elevating the risk of wildfires -- a little-known side effect that is particularly concerning in light of prolonged draughts in the region and mounting concerns about climate change.

And it’s a problem that isn’t limited to the congested metropolitan area of South Lake Tahoe City, but also affects Placer County, on the north and west ends of the lake.  Because of location and topography, air quality around the lake can often be elevated beyond what is considered reasonable by national standards. During fire season, air quality can reach dangerous levels.

“We actually have a pretty significant fire about every other year in Placer County, so it is always on our minds,” said Brett Storey, who serves as senior management analyst and biomass program manager for Placer County.

Storey explained that air pollution from recent fires, such as last year’s Rim Fire and American Fire, underscored the need for finding new ways to get rid of the brush and deadwood that was culled during fire abatement efforts. Traditional methods involve piling and burning biomass that for physical reasons wasn’t hauled out of the forest. Storey said the practice, while necessary, was actually contributing to the air pollution.

The answer that the county came up with would not only cut emissions by more than half, but once up and running, could contribute power to the local utility company, Liberty Utilities.

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According to Stangl, who has constructed two other biomass plants in California, the operation has ecological benefits as well. Biomass gasification uses extremely high temperatures to convert the organic carbon-based materials into gases and char. The gases are then separated and used to produce electricity that in this case, would be sold to the local power company. The remaining biochar would be sold as fertilizer, or used as a nontoxic filter media.

Unlike older biomass systems, Stangl explained, emissions are almost negligible with gasification. The carbon is, for the most part, retained in the biochar.

“Each day I can put the carbon we make on a scale and tell you precisely how much carbon did not get emitted because it is left in solid state,” Stangl said. “We sell to large farms, citrus owners in Fresno County, avocado growers in San Diego, grape growers in the Bay Area, leafy greens and strawberry growers in the Monterey area. And they put that in the soil.”

For the Air Pollution Control District of Placer County, the idea of a biomass gasification unit that can reduce the amount of pile-and-burning for fire mitigation is promising news as well. Bruce Springsteen (no relation to the singer), who is an engineer for the agency, explained that the plant would be required to apply for air permits from the agency before it could operate. He said that while his agency was not involved in spearheading the plans for the plant, he could see the direct benefits of not having to rely on pile-and-burn methods for the majority of hazardous fuel mitigation.

“Our agency is very supportive of the utilization of woody forest waste biomass that comes from fuel treatments and forest management practices,” said Springsteen. “We, and the land managers, feel [it] is critical for forest hazard reduction and returning the forest to a fire-resilient condition.” The  burning, he said, was often a “necessary evil” in fire mitigation that he hoped would be reduced if and when the gasification plant went ahead.

“[We have] done a lot of work to determine the huge air quality benefits that come from using this material in energy facilities. Well-controlled, well-designed ways of burning it or gasifying it produces good, renewable electricity or energy.” He said the air emissions associated with such facilities are “much lower than the alternative, which is putting it in a big pile and lighting it on fire.”

According to Storey, emissions from gasification were estimated to be at least 75 percent less than from pile-and-burn methods.

“If we build this, we will have the ability to grab all of that wasted material. And no longer will it have to burn in open piles, but we will be able to convert it into energy that will all have good pollution air-control systems, so the emissions will be 75 to 99 percent less than [pile-and-burn methods].”

Storey admitted that the plant still has some hurdles to jump, which includes having it authorized for operation by the Air Pollution Control District. But he said the unique cost-sharing that has emerged from the project is what will likely make it a success.

Placer County has just finalized an agreement with the U.S. Forest Service's Lake Tahoe Basin Management Unit to transport biomass to the plant and is in the process of finalizing agreements with other agencies for the same work. The cost of the pick-up (within certain distances) would be split between the county and the Forest Service. Storey said that agreement alone speaks volumes about the potential of this project.

“Because now [agencies] see that we have a long-term supply solution of grabbing the material,” a point that may also help with securing any further funding for the construction, Storey said. “This is a joint problem for us, and we are trying to provide joint solutions.”

The cost of the project has been met from a variety of sources, including matching grants from the Department of Energy, in-kind work from both county and federal agencies, and funding from Stangl. Storey said the county has put about $1.5 million into the investment.

The capacity of the plant will be fairly small for a gasification plant, about 17,000 bone-dry tons of waste a year. Preconditions require that the fuel must be third-party certified to be waste that would have been designated for pile-and-burn disposal. Storey told us these conditions were set early on in the planning, but also address concerns from local residents that other parts of the forest remain protected. Both he and Stangl noted that while gasification can handle most of the waste product that would come from fire mitigation efforts, there may be some biomass that will not be accessible by vehicle due to location and will still have to be piled and burned.

Storey said that if all goes according to plan, the county hopes to begin construction by spring of next year -- and for the plant to be up and running by early 2016. With the likelihood of more fire seasons in the future, that’s good news for the Lake Tahoe region and its residents.

Image courtesy of Phoenix Energy