ENCOURAGING SUSTAINABLE AGRICULTURE THROUGH BIOMASS ENERGY
Introduction/Abstract
Operation of biomass energy projects in agricultural settings can result in stabilization of wastes, reduction of odors, reduction of greenhouse gas emissions, and generation of renewable energy sources. In biomass energy, agricultural wastes are anaerobically treated in digesters where microorganisms metabolize wastes and produce biogas. The biogas contains high concentrations of methane that can be used to fuel engine-generators, resulting in the production of electricity and heat. Although there are many advantages of biomass energy, the technical issues require clarification prior to implementation of such projects on a large scale.
Purpose
In our work we have investigated the use of agricultural waste products in anaerobic digestion. Specially, we have targeted agricultural waste products that are prevalent in California such as grape pomace from the wine industry and egg waste from packing plants. Characterization of these waste products has included performing a host of laboratory tests to determine the salt and nutrient content of each waste. Additionally, we have conducted laboratory batch tests to determine both the ultimate bio-methane production of various agricultural waste products and the rates of bio-methane generation. We have also conducted economic and environmental assessments for a full-scale biomass energy system.
Method
Laboratory experiments were conducted in accordance with Standard Methods. Bio-methane potential tests were conducted in temperature-controlled incubators. Samples were prepared anaerobically in a glove box. During the multi-day tests, pressure was measured and recorded automatically. Methane content was measured periodically using gas chromatography. A three liter flow-through anaerobic reactor was maintained and used to inoculate the batch test bottles. Full-scale assessments were performed at a biomass energy project that has 1.9 million liters of anaerobic digester capacity and a 710 kW generator.
Results
Batch test results indicate that the grape pomace and egg waste have ultimate methane potentials of 99.0 L CH4 kg-1 VS and,484.1 L CH4 kg-1 VS respectively. Results of a 20 year life cycle assessment of the full-scale system indicate that the biomass energy system is economically sustainable, based on a positive net present value. However, selection of off-site agricultural waste products must be done carefully to avoid accumulation of salts and nutrients on farms.
Significance
The work that we have done demonstrates that biomass energy can be sustainable, but that systems must be designed and operated appropriately. Grape pomace and egg waste appear to present viable options for anaerobic digestion. Additional investigations are warranted to further demonstrate the feasibility of full-scale implementation.
Location
DeRosa University Center, Stockton campus, University of the Pacific
Format
Poster Presentation
ENCOURAGING SUSTAINABLE AGRICULTURE THROUGH BIOMASS ENERGY
DeRosa University Center, Stockton campus, University of the Pacific
Operation of biomass energy projects in agricultural settings can result in stabilization of wastes, reduction of odors, reduction of greenhouse gas emissions, and generation of renewable energy sources. In biomass energy, agricultural wastes are anaerobically treated in digesters where microorganisms metabolize wastes and produce biogas. The biogas contains high concentrations of methane that can be used to fuel engine-generators, resulting in the production of electricity and heat. Although there are many advantages of biomass energy, the technical issues require clarification prior to implementation of such projects on a large scale.
