Owners: Constellation Energy and North American Power Group Ltd.
Operator: Constellation Operating Services Inc.
By 2008, the 19-year-old wood-fired Rio Bravo Rocklin Power Station’s operating performance had been significantly degraded by boiler erosion and corrosion caused by (among many other problems) poor fuel. After much consideration, the plant owners elected to invest in a comprehensive upgrade to restore the plant to its as-built performance. Today, the plant operates very reliably. A newly implemented predictive maintenance program should continue to drive down operating costs and further reduce the number of forced outages.
Wood is good. It’s renewable and can be recycled in many ways. Waste wood products can also be used as renewable fuel for power generation, and California is probably more aware of this potential than any other part of North America. More biomass-fired generation units will be needed to meet that state’s audacious goals for renewable generation, but those units — like all renewable power generation technologies — will need to observe rigorous operation and maintenance (O&M) practices if they’re to deliver on their promise. One of our Top Plant awards in the renewables category goes to a plant that has learned that lesson and now points the way to success for others.
Biomass in California
California Governor Arnold Schwarzenegger’s April 2006 Executive Order S-06-06 extolled the virtues of biomass energy and called for the Golden State to produce 20% of its renewable electricity from biomass by 2010 and maintain that level through 2020. That goal was part of the state’s renewable portfolio standard (RPS), approved in 2006, requiring 20% of electricity to be powered by renewable sources by 2020. Schwarzenegger’s Executive Order S-21-09, signed on September 15, 2009, increased California’s RPS to 33% by 2020 — a very ambitious goal, especially for biomass-fueled power plants, whose megawatt-hours haven’t increased over the past 10 years. (See the table for the actual numbers.) All of the state’s RPS goals exclude large hydroelectric power sources that currently supply roughly 8% of the electricity consumed in California.
California’s historic energy mix. Biomass-fueled power generation has remained unchanged over the past 12 years. Electricity consumption is in MWh. Source: California Energy Commission
The entire biomass power plant fleet in California numbers around 50 and has a gross capacity of approximately 968 MW. These plants are typically solid-fueled combustion power plants and engines, boilers, and turbines operating on landfill gas, sewage digester gas, and biogas from animal manures. Another six projects totaling about 180 MW are advertising commercial operating dates in the last quarter of 2009, although four will burn municipal solid waste.
Of the 968 MW total, 136 MW is fueled by agricultural biomass, 262 MW by in-forest biomass and mill residues, and 570 MW by the biomass fraction of municipal wastes. Biomass projects operating at the end of 2008 supplied about 1.9% of the state’s electricity consumption needs, far short of Schwarzenegger’s 4% goal (20% of 20%) originally set for 2010. The odds don’t look good for meeting the biomass portion of the 2020 RPS goals.
The California biomass electricity market segment grew quickly in the 1980s, when more than half of the 50 biomass plants were constructed. These plants, representing about 625 MW, were constructed between 1983 and 1990 when lucrative power purchase agreements (PPAs) and production tax credits were available. The remaining third of the plants, those built since 1990, are generally smaller, and few use conventional solid-fuel combustion or selected municipal solid waste collection and combustion technologies.
Email
Comments
Print
Reuse
