Planned California biomass plant aims to use dead trees

By Anna Simet | February 07, 2017

A proposed 2-MW biomass power project in California’s Mariposa County is one step closer to reality.

The Mariposa Biomass Project, a non-profit community group in Mariposa, California, recently closed escrow on two parcels for its future location, the group announced. It will be located in the Mariposa Industrial Park, near the Mariposa County Solid Waste Facility and PG&E substation.

The project received a USDA U.S. Forest Service 2016 Wood Innovations grant of $244,000, and is in the running to score a $5 million California Energy Commission EPIC grant.  Stephen Smallcombe, the group’s CTO said that the EPIC grant is critical to the project moving forward. A similar biomass power plant in North Fork, California, currently being constructed by Phoenix Energy, was a previous EPIC grant recipient.

Smallcombe has worked closely with the group’s CEO, engineer Jay Johnson, and other community members, to select a developer and find a suitable site for the project.  The project hopes to take advantage of California’s SB 1122, or BioMAT (Biomass Market Adjusting Tariff), which supports small-scale forest biomass energy projects. At anticipated rates, the tariff could provide the project with up to $3.5 million dollars of annual revenue.

Qualifying for BioMAT has historically been a lengthy, complicated and expensive process to work through, requiring multiples bidders and a hefty interconnection down payment, according to Smallcombe. So far not one kWh of electricity has been produced under this program.  However, a recent rule rewrite by the California Legislature, guided by the governor’s Tree Mortality Task Force has simplified the process and now allows projects to participate in the auction without the previously required interconnection fee down payment of 30 percent of the projected $2 million interconnect cost.  It is not easy for these small-scale biomass projects to come up with $600,000 a year or more before any possible revenue stream, Smallcombe said.

Building on the state’s current push to remove and utilize millions of dead and dying trees susceptible to catching fire or falling on houses, the plant will use nearby forest waste as fuel via a multi-stage gasification technology supplied by Cortus Energy. “The Sierra has over 100 million dead trees right now, and in Mariposa County and many of our communities in the foothills, there’s about 98 percent mortality of pines, so we have biomass coming out of our ears right now,” Smallcombe said.

In late 2015, California Gov. Jerry Brown declared the situation a state of emergency and laid out the groundwork aimed at combatting the issue, with some emphasis on getting that material to bioenergy facilities. Some of the ag-based Central Valley plants that have or were going to go out of business as a result of expired PURPA contracts and inability to secure new ones at profitable rates have benefitted from some of Gov. Brown’s initiatives. “So far, I believe six is the latest count of power plants that have been saved or reestablished new contracts and are not shutting down,” Smallcombe said. “So that’s good news. They’re taking a lot of fuel in from dead trees, but they’re full now, and there’s still a glut of fuel.  Small-scale biomass plants located near the source of the fuel, like the one the project hopes to build, will help with the economic viability of disposing of the dead trees by minimizing transportation costs.

Though the Mariposa project developers are anxious to secure a power purchase agreement and come online, Smallcombe said several things have to be done yet, including the upcoming completion of a system impact study with PG&E, permitting with the county, and securing the EPIC grant needed to help finance the project.

Smallcombe said he expects to find out if the project will receive the grant in March or April.