Biomass fuels are derived from renewable energy sources such as timber, agriculture and food processing wastes, fuel crops, and sewage sludge. Although biomass is a significant source of energy in developing countries, one factor limiting the widespread use of biomass concerns the inefficiency associated with traditional combustion methods. However, private and public research and development of improved combustion processes are ongoing - if an effective, scalable process that meets cost and environmental expectations is found, the use of biomass could help California meet the state and national bioenergy targets set forth in the Renewable Portfolio Standard (RPS), Low Carbon Fuel Standard (LCFS), and Renewable Fuel Standard (RFS). [1]
California boasts three major biomass resources: agricultural residues, forest residues, and urban wastes. The state produces more than 86 million bone dry tons (BDT) of which 36 million are categorized as "available for use on a sustainable basis." [1] According to a report published by the California Research Bureau breaks this down as 30% from agriculture residue, 40% from forestry, and 30 from municipal solid wastes. [2]
This same report notes that there are sufficient biomass resources in California to generat 4700 MWe, which amounts to 12% of the 2005 statewide demand of electricity. Advances in conversion efficiencies and aggrandizement of biomass resources may increase this to as much as 7,100 MWe by 2017. [2]
Two methods are available for the conversion of biomass: thermal technologies and biochemical systems. Often, level of moisture content is used in selecting the conversion technology. For example, low moisture biomass such as wood and paper undergo thermal processes, whereas high moisture material such as manure and food waste are converted with biochemical processes. [1]
The success of biomass as a renewable energy source is linked to the economic feasibility of the process of converting biomass into a fuel. According to Moller, the commercialization of biomass energy necessitates a streamlined system integration of production, handling, conversion, product marketing, and environmental management. [2] In other words, the economic feasibility of the process is a complex function of feedstock, product, and site.
Benefits of biomass energy are abundant: cleaner environment, landfill diversion, fuel diversity and job creation. The use of biomass as an energy source will reduce atmospheric pollutants, greenhouse gases, fossil fuel emissions and the risk of wildfires. Air quality should positively benefit from agricultural residue no longer being disposed through open burning. Biomass energy can help alleviate price jumps of fossil fuels and decrease the dependence on foreign energy sources. Jobs are expected to be created given the laborious nature of biomass energy. [2]
There are a number of challenges that interfere with the sustainability of biomass energy. First, "large-scale demonstrations of biorefineries producing biofuels from lignocellulosic feedstocks and advanced power-generation options must be completed" before commercial conversion processes can be appropriately developed. Construction of new facilities will inevitably raise concerns about air emissions and water supplies, water quality, and waste disposal will have to be adequately addressed. Other significant challenges include: permitting complexity and cost, increasing feedstock costs, and development of performance-based sustainability metrics and standards. However, long-term economic benefits encourage the development of biomass energy. [1]
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[1] B. Jenkins
[2] R. M. Moller, "Brief on Biomass and Cellulosic Ethanol," California Research Bureau, CRB 05-010,December 2005.