Solutions To Assignments


Assignment 1:


Solutions Manual for Green Engineering: Environmentally Conscious Design of Chemical Processes

 


Assignment 2:


Sample Reports:

**Thanks to the students at The University of California Santa Barbara for the use of their reports**

Sample Report 1: Battery Electric Vehicles vs. Hybrid Electric Vehicles

Sample Report 2: The Refrigerator: 1960 vs. 2000

 


Assignment 3:


1.                  What is the most energy intensive sector of the chemical industry (measured as total life cycle energy use per million dollars of sales)?  What fraction of that energy is used by the industry itself, and what fraction is used by the sector’s suppliers? 

The EIOLCA approach divides the chemical and plastics manufacturing sectors into the 14 sectors shown below. 


Based on data drawn from the EIOLCA web site in 2000 (note that the economic, energy use, material use and emission data are periodically updated, so the current version of the site may lead to slightly different answers), the energy use in these 14 sectors is given below.  The energy use in each sector is segregated into three categories: energy use in the sector being analyzed, energy use by the sector’s suppliers (other than electric utilities) and energy use by electric utilities supplying the sector.  Fertilizer manufacturing is the most energy intensive sector, both for the energy used by the sector and for total energy used by the sector and its suppliers.


 

  1. What suppliers to the automotive sector have the greatest emissions of SO2 (or carbon dioxide or nitrogen oxides or toxics)?

The EIOLCA web site indicates that the largest contributor to SO2 emissions associated with passenger vehicle manufacturing is electricity generation.  The results are shown below.

     Results for Motor vehicles and passenger car bodies

  1. What fraction of the energy used over the entire life cycle of a passenger vehicle (including vehicle use) is associated with its manufacture?
The EIOLCA web site indicates that if we spend $20,000 (the purchase price of a new vehicle) in the motor vehicle manufacturing sector, a total of 0.25 terajoules of energy is consumed throughout the economy.  If the vehicle is driven 120,000 miles over its lifetime and gets 20 miles of travel per gallon of gasoline, the vehicle will consume 6,000 gallons of gas over its life.  A gallon of gas, when burned, releases approximately 108 Joule.  Over the lifetime of the vehicle, the gasoline used will be 1011 to 1012 Joule (6*1011 Joule for a vehicle getting 20 mpg, driven for 120,000 miles) .  A terajoule is 1012 Joule, so the energy invested in making the vehicle is comparable to the energy consumed in use (30% of the life cycle energy consumption is due to manufacture for a $20,000 vehicle getting 20 mpg, driven for 120,000 miles).