Hydrogen Cars versus ICE Cars (16 points)
A hydrogen fuel cell electric passenger vehicle (FCEV sedan) has the following properties:
- Hydrogen Fuel Manufacturing Pathway (raw material phase included): Reformation of North
- American natural gas into compressed hydrogen at a central steam methane reformation (SMR) plant; includes liquefaction and re-gasification
- For details about the carbon intensity of this pathway (note that all carbon intensity pathways are given in gCO2e/MJ of hydrogen fuel):
- California Environmental Protection Agency Air Resources Board, no date, “Detailed California Modified GREET Pathway for Compressed Gaseous Hydrogen from North American Natural Gas.” https://www.arb.ca.gov/fuels/lcfs/121514hydrogen.pdf, accessed 2/23/2019 at 5:00pm
- FCEV Efficiency: 81 miles/gallon (mpg) of gasoline equivalent or ~ 0.66 miles/MJ of hydrogen fuel
- Total Vehicle Manufacturing + Maintenance Carbon Emissions: 11.8 metric tons CO2e
- Total Vehicle carbon from infrastructure construction and operation: 11.20 g CO2e/PMT.
- Total vehicle lifetime miles: 160,000 miles
Note: PMT refers to passenger miles traveled.
a) Use this information to calculate the life-cycle vehicle carbon emission factor for the FCEV in gCO2e/PMT. (Assume an average vehicle occupancy of one passenger, and for simplicity, you can neglect end-of-life emissions. (6 points)
b) From your calculated emission factor, calculate the life-cycle percent CO2e savings from driving a FCEV as opposed to a typical one-passenger 35 mpg internal combustion engine sedan across various stages of each vehicle’s life-cycle as well as in total. The life-cycle stages that you should consider are: fuel production + manufacturing, vehicle manufacturing + maintenance, vehicle use, and infrastructure construction and maintenance. (hint: use http://www.transportationlca.org/tlcadb-passenger.php to find life-cycle data regarding the 35MPG sedan) (10 points)
(Reference: Transportation life-cycle assessment (2019), Passenger Transportation LCA Database, http://www.transportationlca.org/tlcadb-passenger.php, accessed 2/23/2019 at 5:00pm)