Transportation: oil and pure electric vehicles

ENV 170, Due: Tuesday 5/24

Please answer on a separate sheet of paper. For all calculations, write out your calculation clearly and include units. Partial credit is given for providing the answer only, even if it is the correct answer.

1. Think of your weekly driving or riding around in other people’s cars or on the bus. If you do no driving at all and no bus riding, let’s pretend you are the average American and drive 40 miles per week.

(Burning 1 gallon of gasoline emits 19.4 lbs of CO2, while burning 1 gallon of diesel emits 22.2 lbs of CO2.)

a. Estimate the number of miles you “drive” per week.

You might use google maps ( to help determine distances.

b. How much fuel (in gallons) do you use in a typical week, either driving or riding the bus?

You’ll need to know your average miles per gallon for your vehicle. (Try here: ) If you ride the bus, Seattle’s diesel-electric bus gets 3.8 miles per gallon of diesel. Make sure to take into account the average number of people on the bus

c. How much carbon dioxide (in pounds) is emitted as a result of your transportation in one week?

2. Congratulations! You have been awarded an electric vehicle for being such a good student. Your pure electric vehicle (PEV) requires 0.24 kilowatt-hours for each mile you drive.

a. How much electricity would you need each week (in kWh)?

Use the number of miles you drive per week in part 1a.

b. One argument against electric vehicles is that they simply shift greenhouse gas emissions from your tailpipe to the power plant, so they are not doing any good. Let’s compare . . . Using the table below, how much CO2 (in pounds) is emitted from your weekly travel with your PEV if your electricity is generated exclusively with coal?

c. … if your electricity is 72% hydroelectric, 11% coal, 8% nuclear and 9% natural gas? (Seattle!)

Electricity generation / Coal / Natural Gas / Nuclear / Hydro-electric / Photovoltaics / Wind / Wood
lb CO2/kwh / 2 / 1.02 / 0.013 / 0.009 / 0.231 / 0.028 / 3.3

*

d. Another argument against PEVs is the strain they would put on the electric grid. Let’s see the impact… If 1/4 of the people in Seattle (population 563,374) owned and drove PEVs, how many hours would it take to charge all of these vehicles for a week’s worth of driving? Use 40 miles per week driven by the average American and let’s assume the PEVs were charged using the Centralia coal plant, operating at full capacity (1340 MW, or 1,340,000 kW)?

e. What about if the PEVs were charged using Seattle’s hydroelectric dams on the Skagit River (800 MW, or 800,000 kW)?