We conducted a life-cycle assessment (LCA) of ethanol production via bioconversion of willow biomass crop feedstock. Willow crop data were used to assess feedstock production impacts. The bioconversion process was modeled with an Aspen simulation that predicts an overall conversion yield of 310 liters of ethanol per tonne of feedstock (74 gal per US short ton). Vehicle combustion impacts were assessed using Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) models. We compared the impacts of bioconversion-produced ethanol with those of gasoline on an equivalent energy basis. We found that the life-cycle global warming potential of ethanol was slightly negative. Carbon emissions from ethanol production and use were balanced by carbon absorption in the growing willow feedstock and the displacement of fossil fuel-produced electricity with renewable electricity produced in the bioconversion process. The fossil fuel input required for producing 1 MJ of energy from ethanol was 141 percent less than that from gasoline. More water was needed to produce 1 MJ of ethanol fuel than 1 MJ of gasoline. The life-cycle water use for ethanol was 169 percent greater than for gasoline. The largest contributors to water use were the conversion process itself and the production of chemicals and materials used in the process, such as enzymes and sulfuric acid. The authors are, respectively, Masters Student, College of the Environment, School of Environmental and Forest Sci., Univ. of Washington, Seattle (budsberg@uw.edu); Masters Student, College of the Environment, School of Environmental and Forest Sci., Univ. of Washington,

In this paper we develop an inventory model for deteriorating items with price sensitive demand. Generally the vendor offers a cash discount or fix time period to the retailer to pay all the dues. According to the availability of money the retailer chooses his/her option. In this paper we discuss the possible cases of permissible delay and cash discount. The shortages are allowed in this model and are partially backlogged. Holding cost is considered as varying function of time, which reflects a more realistic concept. The purpose of this study is to optimize the overall cost of the system and to compute optimal ordering quantity. Numerical examples for different cases are also presented to illustrate the study. A sensitivity analysis with regard to distinct associated parameters is shown to make sure the constancy of the model.

In today's era of higher competition in the business, there are many conditions such as offered concession in bulk purchasing, seasonality, higher ordering cost, etc., which force a retailer to purchase more quantities than needed or exceed the storage capacity. So in this situation the retailer has to purchase an extra warehouse named as rented warehouse to stock the extra quantity. In this paper an inventory model for deteriorating products with selling price dependent rate is developed. The occurring shortages are assumed to be partially backlogged and cycle time is also variable. The purpose of the development of this model is to compute the amount and time of order which can optimize the total average cost of the system. A solution procedure and numerical example are presented to illustrate the implementation of the proposed study. Sensitivity analysis concerning with distinct system parameters is also presented to demonstrate the model.

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