Carbon footprint for various modes of transport

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Joined
Jul 29, 2019
Messages
604
Location
Greensboro, NC
I want to have a lesson for my Earth/Environmental classes that looks at transit and the carbon footprint of the choices we make.

I was thinking of having the students plan a trip within the US and see what can be done without a personal automobile. As much as I would like to stay in the metric system being a science class I assume these numbers are going to be easier to come by on a per mile basis.

CO2 per mile for a taxi (25 mpg)
CO2 per mile for a city bus (I found out that Greensboro has one of the largest EV bus fleets in the country and certainly our state but still mostly diesel buses on our streets.)
CO2 for a trip on a subway for a larger city if that is what is visited.
CO2 per mile for an intercity bus (would that be different than city transit. I assume not.)
CO2 for a plane landing and taking off as that seems to be a large part of the planes CO2 emission and then
CO2 per mile for a plane while cruising. Is there a big difference between a smaller jet that serves my local PTI versus the large jets that serves a NYC or London?
CO2 per mile for Amtrak for Diesel
CO2 per mile for Amtrak for the NEC and the electrified routes in Michigan.

What am I leaving out?

Does anyone have reasonably up to date numbers? Would trade groups that deal with these different modes of transport have numbers they are willing to give out to the general public? I likely will have the students price the trip out as well but that is the easy part with all the websites, though I likely will give them a budget to deal with.
 
Hello,

Great project! A few remarks:
- maybe that's implied, but you should of course account the co2 emission per mile *per passenger* (which means the emissions for a bus trip will widely vary depending on the local average load factor)
- for electric powered modes, how the electricity is produced will be a great deal. As of right now, electricity produced in California emits 69g of co2 per kWh, while it's 753g of co2 per kWh in South Carolina: https://app.electricitymaps.com/map
- yes, the size of the aircraft will have an impact on how much co2 it emits, as well as how long the trip is (the longer it is, the lower the emissions per km are, as take-offs require a lot of energy), but how new the engines are is also a factor: an Airbus A320neo (New Engine Option) will emit 18% less co2 than a A320 "ceo"
- you're leaving out bicycle (bike or e-bike)! A bicycle allows you to get to a 5 mile radius within 30 min, so that's a both quick and efficient mode of transportation for local trips... as long as the road infrastructure in made so that you won't get killed by motorists within minutes

If you can read French, https://impactco2.fr/transport will give you a simulation of co2 emissions of different modes of transportation depending on the distance, and taking in account the emissions occuring during the manufacturing process (for electric vehicles, the gCO2/kWh used is the average in France, so a rather low figure)
 
Hello,

Great project! A few remarks:
- maybe that's implied, but you should of course account the co2 emission per mile *per passenger* (which means the emissions for a bus trip will widely vary depending on the local average load factor)
- for electric powered modes, how the electricity is produced will be a great deal. As of right now, electricity produced in California emits 69g of co2 per kWh, while it's 753g of co2 per kWh in South Carolina: https://app.electricitymaps.com/map
- yes, the size of the aircraft will have an impact on how much co2 it emits, as well as how long the trip is (the longer it is, the lower the emissions per km are, as take-offs require a lot of energy), but how new the engines are is also a factor: an Airbus A320neo (New Engine Option) will emit 18% less co2 than a A320 "ceo"
- you're leaving out bicycle (bike or e-bike)! A bicycle allows you to get to a 5 mile radius within 30 min, so that's a both quick and efficient mode of transportation for local trips... as long as the road infrastructure in made so that you won't get killed by motorists within minutes

If you can read French, https://impactco2.fr/transport will give you a simulation of co2 emissions of different modes of transportation depending on the distance, and taking in account the emissions occuring during the manufacturing process (for electric vehicles, the gCO2/kWh used is the average in France, so a rather low figure)
I do need to account for passenger load and I had not thought that far ahead. Glad you mentioned that.

I was going to add bike/ebike/scooter at first and decided to cut that from the list as I wanted to use modes that would get you out of the weather or be usable by someone that was physically impaired. But that is a good point.
 
Well, public transit doesn't exactly get you out of the weather, as you have to walk/cycle between your exact departure point and the nearest bus/subway stop and between the other nearest bus/subway stop and your exact destination, and only very few taxis are able to take passengers on their wheelchair ;)

No mode of transportation can be used by absolutely anyone in absolutely any situation: taxis and planes can't be used by the poorest, public transit / intercity buses can't be used in all the places that have no public transit / intercity bus stop, and public transit usually doesn't run during the night, kids under 16, blind people or people with some health issues can't drive a car (and that's a quite expensive mode of transportation if you include all the costs associated with it), etc.,
So I would include bikes/e-bikes in your study as they are available to most people in most situations (you don't have to "stick" to a mode of transportation, there's no rule against wanting to cycle 28 days per month when it doesn't rain, and taking your car 2 days per month when it rains)

One thing I forgot in my remarks: you should consider separatly "day-to-day trips" (most of your trips within a day will be only a few miles at most) and "long-distance trips" (for example going to / coming back from a vacation place, something that will happens a few times a year a most)
For day-to-day trips, you'll pick between walking, cycling, public transit, taxi, driving, or a combination of these, but no Amtrak, intercity buses, or flights in sight there.
For long distance trips, Amtrak, intercity buses, driving, flights, will be among the options: most people won't like cycling or taking public transit for days before reaching their destination.

And coming back to bikes/e-bikes: for most day-to-day trips, they will usually offer the best door-to-door speed / cost ratio! Cars/taxis might be faster (except in very dense cities due to congestion and lack of parking space), but they're much more expensive, public transit might be quite affordable... but unless you have a stop just in front of your departure and destination, with a direct and frequent line between these two places, public transit will be much slower!
A good experiment to observe that: in Google Maps, pick any city (large enough to offer public transit), pick a random departure and destination within the city, and look at the trip duration shown for the different modes of transportation:
Sans titre.png

But again, almost no one will use a bicycle if your streets are only designed around cars, no on will walk if your streets have no sidewalk: if people in the Netherlands use their bikes so much, it's not because of "their culture", but only because they have a proper cycling infrastructure in their streets and roads, that allows anyone who'd like to safely and comfortably use a bike.
 
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Let's not forget motorcycles
harley GIF
 
This is for 9th graders in high school for what it is worth, though I do a lot with spreadsheets so they can learn some life skills while we learn other facts about the world (and maybe about trains as well.) so I can't make this too complicated. I likely should have mentioned that on the original post.

However I am appreciating all the comments as this will make whatever I do even better.
 
As I've written before, the most robust way to compare the modes of transportation would be to get recent figures on passenger miles traveled and fuel use, and then calculate fuel use for passenger mile. You then need to calculate the CO2 emissions per gallon of fuel or kWH (for electric traction).

EPA has some guidance: https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references
They claim 8,887 gm CO2 per gallon of gasoline and 10,180 gm CO2 per gallon of diesel fuel.
Greenhouse gas emissions associated with electricity production vary across the country depending on the source of power for the local electrical grid.

I'm not sure if there are accurate consistent statistics of fuel use and passenger miles traveled for each mode of transportation.
For a rail carrier, one has to also include deadhead operations, switchers, and maintenance vehicles. For airlines, you would need to include deadhead operations, airport vehicles, like tugs, fuel trucks, and baggage carts. I'm not sure if Amtrak or airlines publish their total fuel consumption. For taxis, you have to allocate each passenger's share of the cab driving around empty looking for rides.

If you're just looking at the performance of vehicles, there's not a whole lot on trains in the open literature. I saw a poster at a conference a few years ago, where they reported that the 4-car Piedmont train with a capacity of ~250 passengers as having fuel consumption of 05 to 1.6 gallons per mile. (https://www.amtraktrains.com/threads/how-green-are-trains-really-with-data.75161/) Obviously, how "green" that train is depends on how many people were riding the train. This is true of all transportation modes. A car that gets 25 mpg carrying 4 passengers is more fuel efficient and has lower emissions per passenger mile than a single-occupancy car that gets 50 mpg. For trains to be really "green," they need to be full of passengers as much as possible.

Again, if I were making policy, I would do my best to find total fuel use and total passenger miles for each mode in order to see which ones do best.
 
As I recall, he NYT article pointed out that per mile cost comparing planes and trains varies. Passenger jets use most of their fuel while taking off and landing. Thus, trains emit less CO2 on short haul trips, but are dirtier per passenger mile than planes on long haul trips. Most non-electric trains use diesel, and there are a ton of starts and stops on a cross country train trip. So as always, it depends. The many factors to consider in such comparisons greatly complicates arriving at accurate numbers.
 
This type of comparison was popular during the 1970's. The simplest fallacy that kept occurring was the seating density assumed, but rarely footnoted.

The other long-range fallacy was in assuming that all modes were used for the same purposes. That was discussed above, but beyond today's comparisons, people will adjust their home and work locations based on service available. In 2014 I went from my home in Denver to my pension in Berlin entirely by public transportation. There are people in other neighborhoods in Denver that can't get to a burger joint by public transportation. My neighborhood was built around streetcars, cycling and walking; their neighborhood was built around autos.
 
Unfortunately the latter rather than the former has been the trend in the US for a long time and still seems to be the case in most areas.
If we really want to do something about the climate crisis, we should be rebuilding neighborhoods around public transportation, walking and cycling instead of obsessing about "green" gadgetry like electric cars. This might mean starting with building a good local bus network at first, then when the buses get too crowded, there might be more public support for building rail lines.
 
If we really want to do something about the climate crisis, we should be rebuilding neighborhoods around public transportation, walking and cycling instead of obsessing about "green" gadgetry like electric cars.
Changing our development pattern is really the key to making rail and transit useful to a much bigger chunk of the population. But in many communities developed since World War II, local zoning laws effectively prohibit the kind of density needed for walkable neighborhoods -- by restricting whole neighborhoods to single-family houses with minimum lot sizes and setback requirements. You can take a walk in these kinds of neighborhoods, but you can't really go anywhere without a car. And most of the time, any type of commercial activity is prohibited, so going to a store requires driving to a zoned commercial area.
 
If we really want to do something about the climate crisis, we should be rebuilding neighborhoods around public transportation, walking and cycling instead of obsessing about "green" gadgetry like electric cars. This might mean starting with building a good local bus network at first, then when the buses get too crowded, there might be more public support for building rail lines.
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