Numerous factors have pushed energy from biomass to the forefront of policy and industry discussions. Large harvests of traditional crops, low farm prices, dependence on foreign energy sources, and environmental problems have increased interest in renewable energy sources. Tools are needed to evaluate and compare different available feedstocks and to identify parameters and modifications for the production of renewable fuels such as biodiesel. The first paper examines the development of a biodiesel process model using commonly available spreadsheet software and process-engineering principles. The basis of the model is a continuous process with two stirred-tank reactors and sodium methoxide catalysis. The process is modeled as 27 units with 51 flows and 18 components. Mass flow rates and compositions of the process input and output streams are quantified using mass and component balances, energy balances, stoichiometric relations, and established process parameters. Oil composition and rate, methanol:triglyceride ratio, and expected transesterification of triglyceride are the user-specified inputs in the model. Based on commonly reported parameters (6: 1 methanol:triglyceride ratio and 98% transesterification) and a basis of 100 kg/h crude soybean oil, the model computes inputs of 13.8, 10.8, and 34.7 (in kg/h) for methanol, 10% sodium methoxide in methanol, and process water, respectively; and outputs of 93.5, 10.3, and 55.6 for soy biodiesel, glycerol, and waste stream, respectively. In the second paper, the mass flow rate data from the developed biodiesel process model are linked to cost data for evaluating the economic feasibility of biodiesel production in North Dakota with canola oil as the feedstock. Estimations of capital investment cost and total annual biodiesel product cost are conducted for two canola biodiesel production plants with 5 and 30 million gallons per year (MGY) capacities. These capacities were selected based on North Dakota and neighboring states' biodiesel demands, respectively. Capital investment cost analysis shows the presence of considerable economies of scale for the biodiesel production process for the two capacities. These cost calculations are based on the purchased equipment cost calculated from the equipment specifications. Total annual biodiesel product cost analysis shows that the major portion (>80%) of the total product cost is the raw material cost, similar to the analysis of previous economic feasibility studies. Cost benefits from the economies of scale are still present for the fixed charges, general expenses, and the manufacturing costs (other than the raw material costs) in the annual product cost calculations for the two production plant capacities. Finally, based on the gross profit evaluation for both plants, this study concludes that it is more worthwhile to invest in the 30 MGY production plant because of the greater cost returns from the economies of scale benefits. The results are more encouraging after the incorporation of the federal biodiesel tax incentive and favor the investment for biodiesel production in North Dakota. / North Dakota. Agricultural Experiment Station / USDA-CSREES (under Agreement No. 2003-34471-13523)