科研之友
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摘要
This study estimates a variable cost function for corn ethanol plants, using data from a unique survey of Midwest plants. The objective is to better understand the effect of prices and scale of production on Marshallian shutdown price, input choice, and by-product choice. We estimate a novel specification of a cost function capable of accommodating two distinctive features of ethanol plants' technology: (1) the production process results in by-products that can be sold in different forms in response to price signals, and (2) decisions on the mix of by-products may be subject to constraints, such as thin livestock markets or imperfect price foresight. This cost function is estimated by nonlinear seemingly unrelated regression with correlated random effects. Constant returns to variable inputs, homotheticity, and proportionality of by-products to ethanol production, assumptions held in previous studies, are strongly rejected by our analysis. Increases in ethanol production require less than proportional increases in corn and other variable inputs when the increases are achieved through increased capacity utilization as opposed to capacity expansion. Moreover, the reduction in input requirements per gallon, reduces both cost and greenhouse gas emissions per gallon. Constraints in by-product marketing decisions seem to slightly increase Marshallian shutdown price.
- 出版日期2016-9
