chapter 6 text book question number 4 Figure 6-17 shows an abridged portion of the unit process for processing soybeans to make soy oil, which can be...

chapter 6 text book question number 4

Figure 6-17 shows an abridged portion of the unit process for processing soybeans to

make soy oil, which can be used to make alternative fuels. The table has been normalized

per unit of soy oil. For ease of use, all separate energy sources have been aggregated into

a single "Energy" flow. In each question below you will seek to find the amount of

energy associated with producing soy oil and/or soybean meal using allocation and

system expansion methods

Flow (unit) Value

Inputs

Soybean (lb) 5.7

Energy (MJ) 6

Outputs (lb)

Soybean oil 1

Soybean meal 4.48

a) Allocate the input energy flow based on a mass basis.

b) Assuming a market value for soybean oil and meal are $1.05/kg and $0.29/kg,

respectively, allocate the input energy flow on a market value basis.

c) Assuming energy content for soybean oil and meal are 37.2 MJ/kg and 16.2

MJ/kg, respectively, allocate the input energy flow on an energy basis.

provide alternative production data for soybean processing outputs. Use the data as needed to answer questions d and e via system expansion.

Where relevant, consider the case where soybean meal substitutes for two kinds of feed on a protein equivalent basis, and soybean meal has a protein content of 48%.

Assume oils are equivalent as substitutes.

Feed Protein Content Energy Use

(MJ/kg)

Barley 12% 2.4

Corn 9% 2.1

Figure 6-18: Protein Content and Energy Use for Barley, Corn, and Soybean as Feed

Feed Energy Use

(MJ/kg)

Palm Oil 8

Rapeseed oil 18

Figure 6-19: Life Cycle Energy Use for Producing Palm and Rapeseed Oil

d) Currently, soybean meal is the determining product. What is the energy use of the

product in the system?

e) In the future, market conditions may change such that soybean oil is the

determining product. In that case, what is the energy use of the product in the

system?

f) Discuss your various results and comment on which of the methods seem most

appropriate.