Volume 63, Issue 4, 2009
Biomass constitutes a major renewable energy resource for California, with more than 30 million tons per year of in-state production estimated to be available on a sustainable basis for electricity generation, biofuels production and other industrial processing. Annually, biofuel production from these resources could exceed 2 billion gallons of gasoline equivalent, while providing opportunities for agricultural and rural economic development. Continuing research and large-scale demonstrations now under way will test alternative technologies and provide much-needed information regarding costs and environmental performance. Biomass can help meet state goals for increasing the amounts of electricity and fuels from renewable resources under the Renewable Portfolio Standard (RPS) and the Low Carbon Fuel Standard (LCFS), and can similarly help meet national biofuel targets under the federal Renewable Fuel Standard (RFS). Internationally consistent sustainability standards and practices are needed to inform policy and provide direction and guidance to industry.
A key strategy for biofuel production is making use of the chemical energy stored in plant cell walls. Cell walls are a strong meshwork of sugar chains and other polymers that encircle each plant cell. Collectively known as lignocellulose, cell wall material represents the bulk of plant dry mass. Biofuels can be made by releasing sugars from lignocellulose and converting them into fuel; however, this is currently an energy-intensive process. We summarize the barriers to efficient lignocellulosic biofuel production and highlight scientific research recently funded by the U.S. Department of Agriculture and U.S. Department of Energy, both to understand and harness the mechanisms by which plants build cell walls, and to further develop enzymes and microbes that facilitate sugar release and biofuel production.
Cellulosic biomass, which includes agricultural and forestry residues and woody and herbaceous plants, is the only low-cost resource that can support the sustainable production of liquid fuels on a large enough scale to significantly address our transportation energy needs. The biological conversion of cellulosic biomass to ethanol could offer high yields at low costs, but only if we can improve the technology for releasing simple sugars from recalcitrant biomass. We review key aspects of cellulosic ethanol production, including pretreatment and enzymatic hydrolysis technologies that present the greatest opportunities to lower processing costs. Although several companies seek to introduce cellulosic ethanol commercially, innovative measures are needed to help overcome the perceived risks of first applications.
The biofuel industry has received billions of dollars in support from governments around the world, as political leaders respond to new environmental and energy-security imperatives. However, a growing body of research highlights nontrivial costs associated with biofuel production, including environmental destruction and diminished food security, and questions the magnitude of perceived benefits. We discuss the ability of biofuels to accomplish climate change, rural development and energy-security objectives, and consider possible impacts on food production and environmental conservation. We also review methods for judging biofuels, consider how well they contribute to policy objectives, and compare policies that support biofuels.
Biofuels have been criticized for raising food prices and reducing food production. While biofuels have rightly been blamed for contributing to reduced food security at a time of record-high food prices in 2008, they have not been credited with reducing the cost of gasoline, also at a time of record-high prices. We discuss the food-versus-biofuel trade-off associated with biofuel production and model the effects of biofuel production in markets for key crops and gasoline, showing that food consumers lose from biofuels but gasoline consumers enjoy substantial benefits. We also suggest ways to address the food-versus-biofuel debate.
The use of crops and crop residues as feedstocks for biofuels increases domestic and global supplies, creates new industries, and may result in reduced greenhouse-gas emissions. Uncertainty about the best crop and residue sources, technologies for manufacture, future public policy, and the global supply and price of oil make it difficult to predict the best approach. California growers can produce feedstocks from grain, oilseed and woody crops and, in the Imperial Valley, from sugar cane. If the technology for making ethanol or other liquid fuels from cellulose becomes cost-effective, then saline and other wastewaters may be used in biofuel feedstock production of salt-tolerant crops, particularly perennial grasses. However, recent global increases in biofuel production have raised questions about their impacts on food and feed prices, climate change and deforestation. New state laws affecting energy use and mandating greenhouse-gas reductions require that the sustainability of all biofuels be assessed. Sustainability should take into account factors at both the global and local scales, including resource-use efficiency, cropping-system adaptability and the potential of biofuels to remediate agriculture’s environmental effects.
Teenage drivers, particularly new drivers, have higher crash rates than adults. We surveyed 2,144 teenage drivers in California about their driving practices, factors influencing driving behavior, and views on driver education and resources. Teens wanted updated driver education courses and more behind-the-wheel training while learning to drive. They identified parents as their most important resource when learning to drive and also reported that parents were less likely to enforce the rule prohibiting driving with teen passengers than other driving rules. Teens described behavior by teen passengers that distracted them while driving. The findings indicate that new drivers benefit greatly from graduated driver licensing laws.
We used data from 4-H record books to evaluate the 4-H programs in Shasta and Trinity counties. These books are completed annually by youth participants throughout California to describe and quantify their experiences in the program and reflect on their involvement in citizenship, leadership and life-skills activities. Quantitative and qualitative data from the reports was coded according to the Targeting Life Skills model developed at Iowa State University. Most club participants reported life-skill activities in each component of the model (Head, Hands, Heart and Health), in accordance with established 4-H goals. This method is applicable to other counties wishing to perform 4-H program evaluations using club participants’ record books.
Most agricultural systems in California’s Central Valley are purposely flexible and intentionally designed to meet the demands of dynamic markets such as corn, tomatoes and cotton. As a result, crops change annually and semiannually, which makes estimating agricultural water use difficult, especially given the existing method by which agricultural land use is identified and mapped. A minor portion of agricultural land is surveyed annually for land-use type, and every 5 to 8 years the entire valley is completely evaluated. We explore the potential of satellite imagery to map agricultural land cover and estimate water usage in Merced County. We evaluated several data types and determined that images from the Moderate Resolution Imaging Spectrometer (MODIS) onboard NASA satellites were feasible for classifying land cover. A technique called “supervised maximum likelihood classification” was used to identify land-cover classes, with an overall accuracy of 75% achievable early in the growing season.
We used 11 years of data from video auction sales across the western United States to address two long-standing questions posed by California cattle ranchers. First, as expected, ranchers receive lower prices for cattle sold here compared to prices received by ranchers in the Midwest. Second, some (but not all) “value-adding” production and marketing practices raise prices received by ranchers. We report the average amount of location discounts and quality premiums for several market regions.