# Methods Cases modelled Three operating cases are considered

All cases are based on an ethanol fermentation initial liquid volume of 8000 L, which is considered representative of farm-scale production (though this assumption does not affect the overall LY-411575 balance). It is further assumed that two ethanol fermentations of 2.5 days duration each are carried out per week.

The weekly mass and energy flows corresponding to the three cases are calculated for each unit operation (Table 2A to C). The basis for the calculations is described in the following sections. Power ratings for electrical equipment are estimated from equipment manufacturers data and operating data for farm-scale ethanol plants [15] and [16]. Calculations were carried out using Microsoft Excel.

Table 2.

3.2. Pretreatment

As mentioned in the introduction, since most conventional thermal and chemical pretreatments for lignocellulosic materials require excessive energy, the only pretreatment used in the model is grinding. The electrical energy assumed for grinding is 36 kJ/kg, which represents the mid-range of capacity and power for a small scale agricultural grinder (Table A1). This is consistent with published data giving a specific primary energy consumption of 51.6 and 11.4 kWh/tonne for particle sizes of 0.8 and 3.2 mm respectively [1].