The state of California could harvest 34 million bone dry tons of biomass each year on a sustainable basis as a source of renewable energy, according to a report prepared for the California Energy Commission’s Public Interest Energy Research Program.
“The state’s biomass resource is large and diverse,” says the California Biomass Collaborative, author of ‘Biomass Resource Assessment in California in Support of the 2005 Integrated Energy Policy Report.’ This year, the gross annual resource is estimated at 86 million bone dry tons (BDT).
If used for to produce electricity, the gross biomass resource in the state could generate 10,700 MW using current thermal and biological conversion technologies. Of this, 2,100 MW could come from agricultural biomass, 3,600 MW from forestry and 5,000 MW from municipal wastes (including landfill and sewage digester gas.)
“Not all of the resource can, should, or will be used for power, and the technical potential is estimated to be substantially less at close to 4,700 MWe, sufficient to generate 35,000 GWh of electrical energy or roughly 12% of the current statewide demand of 283,000 GWh,” it notes. “With improved conversion efficiencies and growth in municipal, dedicated crop, and some agricultural resources, the state’s annual biomass production might be sufficient to support a potential incremental generation of 7,100 MWe by 2017.”
Without improving efficiencies in generating, incremental potential in 2017 would be closer to 4,800 MW and electrical contributions could reach 60,000 GWh by 2017, or 18% of projected statewide consumption of 334,000 GWh “although generation is unlikely to reach this level without significant additional development support and clear market signals, such as long term contracting opportunities.”
Of the gross resource, 25% is from agriculture, 31% from forestry and 44% from municipal solid wastes, it explains. Landfill gas production exceeds 118 billion cubic feet per year (BCF/y) from 1 billion tons of waste in-place, with a potential recovery of 79 billion BCF/y. Biogas from waste-water treatment plants adds 16 to 18 BCF/y and dedicated energy crops might be produced in future but are not included.
“By 2017, gross annual biomass production might approach 100 million BDT, with about 40 million BDT potentially available for use,” it adds.
Agriculture in California generates products worth US$27 billion from 350 different crops, of which five categories comprise the majority of agricultural biomass: orchard and vineyard prunings and removals, field and seed crop residues, vegetable crop residues, animal manures, and food processing wastes. Agricultural biomass is distributed throughout the state, but most heavily concentrated in the Central Valley. The annual production from woody biomass each year is 2.6 million tons from prunings and tree and vine removals from orchards and vineyards, and 1 million tons are currently combusted as fuel in power plants, generally blended with other fuels such as urban wood and forest materials.
Each residents of California produces two tons of municipal wastes per year, and MSW is the single largest resource for biomass in the state. The biomass component of MSW totals 38 million BDT per year from construction and demolition wood residue, paper and cardboard, grass, landscape tree removals, other green waste, food waste, and other organics, but not plastics and tires. The generation rate is 1 BDT of biomass in MSW per person per year in the state.
About 1.5 million BDT per year of clean construction wood are separated from the waste stream and diverted to biomass direct combustion power plants. The total landfill gas generation from 300 major landfills is estimated at between 118 and 156 billion cubic feet per year for a methane concentration of 50%, compared with 2,200 BCF/y for natural gas consumption.
The gross biomass resource in California would be sufficient to generate more than 10,700 MW of electricity, but “not all of the biomass resource can or will be used for power generation” and the current technical potential is “substantially less, closer to 4,700 MW,” it explains. This capacity could generate 35,000 GWh of electricity, or 12% of the 283,000 GWh of electricity currently used in the state.
The cost to generate green power in California is 4.4c/kWh from landfill gas and 4.9c from wind and 5.4c from geothermal, with biomass direct combustion estimated at 6.6c/kWh. Solar thermal is 12c and solar PV is 23c/kWh, it says.
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This summary of the report is reprinted from the July 27, 2005 issue of “Refocus Weekly” found at: http://www.sparksdata.co.uk/refocus/redesign/showdoc.asp?docid=91036623&accnum=1
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The full text of the 54-page report “Biomass Resource Assessment in California in Support of the 2005 Integrated Energy Policy Report – Draft Consultant Report” by the California Biomass Collaborative** for the California Energy Commission Public Interest Energy Research Program (April 2005) can be found in pdf format at:
It is report #CEC-500-2005-066-D and was prepared under contract #500-01-016.
**California Biomass Collaborative
Department of Biological and Agricultural Engineering
1 Shields Avenue
University of California
Davis, CA 95616
Brian Jenkins – Executive Director
Valentino Tiangco – Project Manager