Driving vs. Flying CO2 Emissions
A NM to CA Road-Trip Comparison
Choosing between traveling by airplane and traveling by car is usually pretty simple. The questions one answers are usually 'How far am I traveling, how much time do I have, how much will a flight cost compared to driving costs, Is there an ocean between me and my destination?' One new factor that some of us are starting to take into account when making travel choices is 'Which mode of travel produces the least CO2?' I've made a direct comparison of two trips between New Mexico and California, one taken by air and the other by car.
I am fortunate enough to have married a wonderful woman and her family lives in Sonoma County, about 70 miles north of San Francisco, CA. Sonoma County is a beautiful place to visit and I expect we will be traveling there on a regular basis. So, with that trip in mind I decided to compare the CO2 emitted when traveling via airplane and automobile between Santa Fe, NM and Sonoma County, CA.
Driving
The mileage from Santa Fe to Sonoma County is just under 1200 miles according to Mapquest, which was quite close to the mileage we recorded. We drove a 2005 Toyota Corolla with automatic transmission, which has an EPA rated 30 mpg city and 38 mpg highway. Our road-trip average was 36.34 mile per gallon which was calculated over our entire vacation. Driving 1200 miles at an average 36.34 mpg equals 33.02 gallons of gasoline burned. According to the Energy Information Administration each gallon of gasoline you burn produces 19.564 pounds of CO2. So for a one way road-trip to Sonoma County we generated 646 pounds of CO2 over the course of the two-day drive.
1200 miles / 36.34 mpg = 33.02 gallons of gasoline
33.02 gallons * 19.564 lbs CO2 per gallon
Driving Total = 646 lbs of CO2 generated driving from Santa Fe, NM to Sonoma County, CA
Flying
For a one-way, non-stop flight from Albuquerque International Sunport (ABQ) to Oakland International Airport (OAK) Webflyer.com calculates a distance of 885 miles, which is definitely shorter than the driving distance. According to the helpful folks at Southwest Airlines that non-stop flight from ABQ to OAK would be one hour and 58 minutes of flying time. Over that flight a 737-300 jet fully-loaded with 137 passengers would burn 10,363 pounds of jet fuel. One gallon of jet fuel weighs 6.7 lbs so 10,363 lbs would equal 1546.7 gallons burned in total. My wife and I would be accountable for 2/137ths of that total or 22.58 gallons of jet fuel burned. Again, the Energy Information Administration says that burning one gallon of jet fuel generates 21.095 pounds of CO2. So flying from ABQ to OAK would generate 476.32 pounds of CO2 for two people on a 737-300 full with 137 passengers.
Now this doesn't take into account our drive to and from the airports. So, the driving would add an additional 131 miles at 36.34 mpg using another 3.60 gallons of gasoline. Burning those 3.60 gallons would generate an additional 70.53 lbs of CO2.
ABQ to OAK = 10,363 lbs of jet fuel / 6.7 lbs per gallon = 1546.7 gallons (for a 737-300)
1546.7 gallons / 137 passengers = 11.29 gallons * 2 passengers = 22.58 gallons
22.58 gallons * 21.095 lbs of CO2 per gallon = 476.32 lbs of CO2 emitted in flight from ABQ to OAK
Plus Driving to and from Airports:
131 miles / 36.34 mpg = 3.60 gallons
3.60 gallons * 19.564 lbs of CO2 per gallon = 70.53 lbs of CO2
Flying Total = 546.85 lbs of CO2 for flight plus drive to and from ABQ and OAK airports
Flying Part Two
I don't know what you expected from that extended algebraic word problem, but I was somewhat surprised that the plane flight generated less CO2 for two passengers than driving did. Admittedly, this is a best case scenario for the plane with a full flight, no delays, stops or the like. Out of curiosity I decided to ask the folks at Southwest Airlines how much jet fuel would be burned if there was an intermediate stop at the Las Vegas airport (LAS). Flying from ABQ to LAS to OAK would burn 14,200 lbs of jet fuel or 2,119.40 gallons. Assuming that the flight was full for both legs of the flight two people would have a share of 30.94 gallons. Burning those 30.94 gallons would generate 652.68 lbs of CO2. Wow! Just one stopover bumps the total CO2 generated well over the driving total.
Flying ABQ to LAS to OAK
14,200 lbs of jet fuel / 6.7 lbs per gallon = 2119.40 gallons of jet fuel
2119.4 gallons / 137 passengers * 2 passengers = 30.94 gallons
30.94 gallons * 21.095 lbs of CO2 = 652.68 lbs of CO2
Plus Driving to and from Airports = 70.53 lbs of CO2
Flying Part Two Total = 723.21 lbs of CO2
Road Trip Musings
Looking at the math above you can see how different factors affect how much CO2 is generated. A plane that isn't fully booked divides the CO2 responsibility between fewer passengers. Just one stop on a flight adds considerably to the CO2 generated. Driving a more or less fuel-efficient car will make a large difference in your CO2 emissions. Flying certainly can be much faster and more efficient than driving over long distances but, it does cut down on the road-trip sightseeing. So, travel as efficiently as you can and enjoy the trip.
Further Reading
Energy Information Administration - Fuel CO2 Emissions
Jet Fuel: 21.095 pounds of CO2 per gallon
Gasoline: 19.564 pounds of CO2 per gallon
Greenhouse Gas Emissions from Transportation and Other Mobile Sources
