Homework 1 (60 points)
Due January 24
th, 2024 at 11:59 PM (Electronic pdf copy in CANVAS)
Problem 1 (20 points)
Using the general chemical formula for burning of a hydrocarbon fuel:
𝑪𝒙𝑯𝒚 + (𝒙 +
𝒚
𝟒
) 𝑶𝟐 → 𝒙𝑪𝑶𝟐 +
𝒚
𝟐
𝑯𝟐𝑶
a) Calculate the 𝑪𝑶𝟐 emissions for diesel fuel (𝑪𝟏𝟐𝑯𝟐𝟑) in g𝐶𝑂2/kWh. Use a specific energy of
12kWh/kg.
b) Calculate the 𝑪𝑶𝟐 emissions for natural gas (𝑪𝑯𝟒) in g𝐶𝑂2/kWh. Use a specific energy of
13kWh/kg.
c) Calculate the emissions of a diesel vehicle operating with 20% efficiency from tank to wheel
(g𝐶𝑂2/kWhtrac).
d) Compare the answer in part c to the emissions value we calculated for a gasoline car: 1565
g𝐶𝑂2/kWhtrac. Which car creates less 𝐶𝑂2 emissions?
Problem 2 (40 points)
As we discussed in class, the emissions of an EV depend heavily upon the cleanliness of the grid
system being used to charge it. We’re going to investigate the influence that some parameters
have on the breakeven point of hybrid gasoline (HEV) and electric (EV) cars. Using the table of
values below:
Source Emissions Vehicle Refueling eff. Powertrain eff. Production
Gasoline 266 g𝐶𝑂2/kWh HEV 0.90 0.285 11106 g𝐶𝑂2 FL grid 411.1 g𝐶𝑂2/kWh EV 0.85 0.80 13.7106
g𝐶𝑂2
a) Calculate the breakeven point (in km driven) for an EV against an HEV in Florida. Use a
drive cycle conversion of 0.1 kWh/km.
b) For many years, Toyota has fought the transition to full EV by investing money in
improving the powertrain efficiency of their HEVs. (There is some merit in this strategy,
considering the base emissions from burning gasoline are less than the national average
grid emissions.) How efficient would the powertrain of the HEV in this example have to
be to break even with an EV in Florida after 150,000 miles of service (240,000 km)?
c) Is it plausible to achieve the answer from part b, considering the maximum theoretical
efficiency of the Carnot cycle is 50% and there are additional losses of the transmission:
~90% efficiency?
d) What do you conclude is the leading factor in why EVs are less emissive than ICEs?