BioCycle October 2008, Vol. 49, No. 10, p. 46
Mark Jenner

CALIFORNIA is under a mandate to reduce its carbon emissions back to 1990 levels by 2020 through the California Global Warming Solutions Act of 2006. With the clock ticking, government jurisdictions in the state are assessing options to comply with the mandate, including renewable energy and energy conservation. One tool to assist in that assessment is a biomass inventory.
Last year, San Benito County, California engaged my company, Biomass Rules, LLC, to conduct a community biomass inventory for the county. A biomass inventory has four components: Estimate of annual energy use; Assessment of available biomass materials; Review of available biomass conversion technologies; and Estimate of energy that could be replaced by biomass materials.
San Benito County is nestled between the California coast and the Central Valley, just south of the San Jose metropolitan area. The county receives about 13 inches of rainfall annually and has a very mild climate. The mild climate helped give the county the lowest per-capita electricity use of all the counties in California. Based on state energy use data from the U.S. Department of Energy’s Energy Information Administration (EIA), and data available from California, San Benito County uses an estimated 7,200,000 MMBtu of energy annually.
The county has a population of 57,000 people with about 889,000 acres of land. It produces $270 million worth of agricultural commodities, mostly from irrigated fruits, vegetables and nursery stock. The 76,000 acres of cropland generated revenues from $3,000/acre to as high as $48,000/acre. Needless to say, this high-valued land was not considered available for biomass energy production. San Benito County is not predominately flat. Eighteen percent of the county is rock. Another 50 percent of the land has an average slope of 30 degrees or more.
To begin my assessment of biomass availability, I tapped into the California Biomass Collaborative (CBC) data, which is an amazing biomass resource. Using county level data from many different federal and state agencies, CBC generates available biomass estimates for agricultural residuals, forestry residuals, municipal wastewater and municipal solid waste (MSW).
The biomass and residual energy resources exist to provide 1,717,503 MMBtu of biomass fuel in San Benito County. Conversion from fuel to energy uses energy. For solid biomass energy conversion a 20 percent energy loss was assumed. This reduced the amount of available biomass resources to 1,374,003 MMBTUs for use in San Benito County, or 19 percent of the county’s estimated annual energy use.
LESSONS LEARNED
A 20 percent replacement of annual energy use with biomass would be a great step forward. Biomass can be a carbon negative fuel, which sequesters more carbon than is released into the atmosphere. This would also offset 20 percent of the energy currently used by ancient carbon, or fossil fuels.
The most productive land, the agricultural crop land, was not included in this assessment of biomass energy. Its value as food producing land is too high to compete for the lower-valued energy crop production uses. This raised several interesting discussion points.
First, it is not critical that a community be locally, energy self-sufficient. The $270 million of produce grown in the county is sent all over the nation and the world. San Benito County can grow food more efficiently than it can grow energy.
Second, there is a trade-off between land used for biomass production and land used for human habitation. USDA data shows that between 1987 and 1997, San Benito County lost 26,000 acres of cropland to urban uses. Between 1980 and 2000, the county’s population went from 23,000 to more than 50,000 people.
Third, even though an expanded use of irrigation for energy crops is not economically feasible, there are new biomass energy crops that could be grown on nonirrigated land. Camelina is an arid mountain oil seed crop that can be grown in San Benito County. There are dedicated lands like the airport, public right-of-ways and the landfill that will not be used for food crops and could be available for energy production. Camelina also appears to do well as an intercrop between orchard and vineyard crops.
Another crop that may have limited application would be growing algae in the city of Hollister’s wastewater treatment plant’s 90 acres of percolation ponds. The city’s new treatment plant is not relying on the existing percolation beds for treatment. If the effluent from the new facility is not used for crop irrigation, the treatment plant could grow 90 acres of algae. At a yield of 4,000 gallons of biodiesel per acre, that would produce 360,000 gallons of fuel annually. At a fuel price of $4/gallon, the gross revenue per acre would be $16,000. This is actually competitive with the gross revenue from the high-valued agricultural land.
Although not part of the biomass inventory, San Benito County has extensive direct solar energy resources. Other reports indicated that at least all the electrical energy demand could be easily replaced with solar energy collectors.
Implementation of targeted projects will allow San Benito County to make a significant contribution to reducing its – and the state of California’s – greenhouse gas emissions. It also will allow the county to meet its energy needs locally, while providing economic stimulus to the local economy.
Mark Jenner, PhD, operates Biomass Rules, LLC and has over 25 years of biomass utilization expertise. Burning Bio News is Jenner’s monthly scorecard of bioenergy project adoption, available at www.biomassrules.com. This column is summarized from Dr. Jenner’s presentation at BioCycle’s 8th Annual BioCycle Conference On Renewable Energy From Organics Recycling, in Madison, Wisconsin.