Since January, I have recorded every time I have consumed fossil fuels to power a form of transportation. I have kept track of what kind of vehicle and I used, how far I traveled, how many people shared that mode of transportation with me, etc. Now, as the school year is coming to the close, I would like to examine some patterns in my chosen transportation methods while I have been a student, and how these contribute to my carbon footprint.
All types of transportation
So far this year, I have traveled a total of almost 7,400 miles in planes (35.7%), boats (for the spring break cruise, 24.4%), cars (39.6%), and public transportation (0.4%). The different carbon intensities of these different modes of travel mean that the distribution of the associated carbon footprint differs slightly in proportion from the distance traveled in each mode:
- Planes: 487 kg CO2eq, 0.19 kg CO2eq /mile, 24.9% of total CO2eq
- Boats: 724 kg CO2eq, 0.40 kg CO2eq /mile, 24.4% of total CO2eq (includes ship fuel only)
- Cars: 738 kg CO2eq, 0.25 kg CO2eq /mile, 37.8% of total CO2eq
- Public transportation: 5 kg CO2eq, 0.164 CO2eq /mile, 0.4% of total CO2eq
- Total transportation: 1,953 kg CO2eq
Clearly, my travels on a cruise ship for spring break have had a very significant impact on my total carbon footprint related to transportation.
Miles traveled in a car
Since driving in a car is the mode of transportation I most commonly use (in terms of frequency and number of trips, not necessarily by mileage), I would like to look more in depth on where these miles are coming from. Note that I have included travel in each personal vehicle I have driven or ridden in this semester, not only my own vehicle.
I have collected several pieces of data regarding transportation by car, including year/model/make of the vehicle (to estimate fuel efficiency), miles traveled, and number of people in the vehicle. I’ve also categorized each trip into one of eight categories: school, work, dance, dining/food, travel/vacation, shopping (non-food), entertainment, and miscellaneous. Some data manipulation has revealed a couple trends that I find interesting:
- Carpooling: About 66% of the miles I have spent traveling in a car have been with at least one other person in the vehicle. However, only about 61% of the total trips in a car (trip defined essentially as one cycle of turning on the engine, driving from point A to point B, and turning off the engine) were with more than one person in the car. From this, I can conclude that I’m carpooling about two-thirds of the time, but I tend to carpool more for longer journeys.
- Reason for travel: By far, dance accounts for the largest portion of miles driven. This accounts for 45% of my miles driven (the next highest category was miles driven for dining and food, at 20%). This is probably because all of the longest distances I have driven this semester (from Houston to Austin, and from Houston to College Station) have been to travel to and from dance events.
I have also compared my driving habits to habits of an average American. The 2009 National Household Travel Survey includes data on the daily person miles of travel per mode of transportation (including private vehicles). Comparison with my own travel habits reveals I generally drive much less for work and work related business but much more for social and recreational activities, which makes sense given my lifestyle as a student and a dancer.
Predictions for off-campus living
Later this year, I’m planning to re-visit this transportation data and examine how my transportation habits change after I’m not longer living on campus. I would like to make a few predictions:
- Amount of carpooling will probably decrease, since I will no longer be offering rides to my fellow students who do not have cars
- Total number of miles driven in a car will probably increase, since I will be commuting to and from work each day.
- I suspect that I will drive relatively more miles for work and relatively less miles for dance. However, since a significant portion of the miles driven for dance were from driving to Austin and College Station for dance events, and I do not anticipate eliminating these trips in the future, I don’t know that this mileage will decrease significantly.