Car's carbon footprint a.k.a. Why I didn't buy a Prius

I bought my first new car in '99 - a Nissan Maxima. It has served me well over the last ten years. I get about 20-22 mpg of mixed city/highway driving.

Our first chance to buy a "green" car, Prius, was some 7 years back. We wanted to add another car when my wife's office moved and we could no longer share the car. Unfortunately, Prius had a 6 month waiting list at that time. We bought a small SUV that gives about 20 mpg - yes, not much worse than my Maxima.

Couple of years back I started wondering whether I should sell my car and get a Prius. Economically it made no sense - we drive too few miles a year for that. So, the change would be mainly to reduce our carbon foot print. I made some calculations to see what would be the car's footprint for the next 10 years. I don't have the original calculations now - but I redid it for this post.

Option 1 : Sell Maxima, buy Prius and use it for 10 years.
Option 2 : Keep using Maxima & buy an EV when it becomes available.

I've converted everything to energy in MBTU, instead of CO2 emissions for fossil fuel based energy. My EV will get green energy. I'm assuming Prius and Leaf cost the same amount of energy in production. Needless to say, the methodology is not to any kind of academic rigor.

I could drive Maxima for 4 years (D5) and still spend less energy,283+113=396 MBTU (D10), compared to what I'd spend on Prius 411 MBTU (B9).



I got the energy to produce Prius from a Slate article (http://www.slate.com/id/2194989). Prius production consumes the equivalent of 900 gallons of gas.

ps : "I got the energy to produce Prius" doesn't mean what it generally might mean.

Two assumptions I might question:

- you have to wait 4 years for an EV. That doesn't seem likely, and if it is less it would tilt the calculation even more away from the Prius.

- there is no carbon footprint for the electricity the EV uses. I guess that could be almost true if your utility uses only nuclear and renewables, but that is rare. This would tilt the calculation more toward the Prius.

There is also the perhaps imponderable "wife factor". Five years down the road she will have a 12-year-old SUV and you will have either a 5-year-old Prius or a fairly new EV. How often will you hear, "Honey, I'm almost out of gas. Can I take your car to the store?" Will it happen more often with the Priius, or the EV? And will it escalate to, "Darling, you know it doesn't make sense for me to drive the SUV twenty miles to work when we could save a lot of gas if you drove it five miles to work and I took the other car. Don't you agree?"

planet4ever said:

Two assumptions I might question:

- you have to wait 4 years for an EV. That doesn't seem likely, and if it is less it would tilt the calculation even more away from the Prius.

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Yes - 4 years is the "break even".

- there is no carbon footprint for the electricity the EV uses. I guess that could be almost true if your utility uses only nuclear and renewables, but that is rare. This would tilt the calculation more toward the Prius.

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We have pretty green power in NW - and I specifically buy "green power".

"Honey, I'm almost out of gas. Can I take your car to the store?"

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If only she asked ! Any new car will face that challenge :lol:

>> I could drive Maxima for 4 years (D5) and still spend less energy,283+113=396 MBTU (D10), compared to what I'd spend on Prius 411 MBTU (B9).

It seems to me that this is true ONLY if you consider your own footprint, and ignore others'. You already own the car, and it has already been built - so you don't have to take the build energy into account personally. But if you look at the bigger picture, you buying a Prius may actually save enery consumption - even if it is not assigned to you directly. Say you sell the Maxima to somebody who was contemplating buying a new Escalade. Presto, more energy has been saved than if you kept the Maxima.

darelldd said:

It seems to me that this is true ONLY if you consider your own footprint, and ignore others'. You already own the car, and it has already been built - so you don't have to take the build energy into account personally. But if you look at the bigger picture, you buying a Prius may actually save enery consumption - even if it is not assigned to you directly. Say you sell the Maxima to somebody who was contemplating buying a new Escalade. Presto, more energy has been saved than if you kept the Maxima.

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I've thought about that without coming to a firm conclusion. I'll expand on this tomorrow ...

This old thread seems like a pretty good spot to mention a good TV show on transportation and oil. It's "e2," aired November 02, 2007 on PBS. It talks about weight; in an ICE car just 1% of the energy of gasoline is used to move the person while the rest is used to move the car itself and lost to inefficiencies. It talks about hydrogen fuel cells and about EVs. Given the broadcast date it's not surprising the only "electric" car it talks about is the Volt. But it's really quite good even so.

Free for Amazon Prime members, $1.99 otherwise.

http://www.amazon.com/Paving-the-Wa...=digital-video&ie=UTF8&qid=1305869393&sr=1-56

In America alone, nearly 70 percent of oil consumed is by the cars we drive. Can efficient automobile design mitigate the environmental damage caused by our beloved cars?

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The PBS web site has podcasts (free) of a number of other interesting looking episodes. http://www.pbs.org/e2/

Before we got our last car, I considered the Prius and did an evaluation to see what the economic breakeven point would be for me, comparing it to the other car we were considering (which got a real world 23mpg city and 30 mpg highway). I ignored any environmental concerns for this comparison. It worked out that I would have to drive 140,000 miles to break even. Long story short, we bought the other car.

evnow said:

Couple of years back I started wondering whether I should sell my car and get a Prius. Economically it made no sense - we drive too few miles a year for that. So, the change would be mainly to reduce our carbon foot print. I made some calculations to see what would be the car's footprint for the next 10 years. I don't have the original calculations now - but I redid it for this post.

Click to expand...

evnow said:

I could drive Maxima for 4 years (D5) and still spend less energy,283+113=396 MBTU (D10), compared to what I'd spend on Prius 411 MBTU (B9).

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darelldd said:

It seems to me that this is true ONLY if you consider your own footprint, and ignore others'. You already own the car, and it has already been built - so you don't have to take the build energy into account personally. But if you look at the bigger picture, you buying a Prius may actually save enery consumption - even if it is not assigned to you directly. Say you sell the Maxima to somebody who was contemplating buying a new Escalade. Presto, more energy has been saved than if you kept the Maxima.

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That's what I say to people to trot out the "but your new car required a lot of energy and resources to build than keeping your old car" line. That's only valid if I junk my current car. Rather, my current car is going to someone who is most like getting a newer, more efficient, car than his/her current car. And ditto that person's car. So I'm actually improving the overall efficiency/greenness of mankind's fleet!

At the very least, my car will be replacing someone else's current car, so yes, my new car is not free in term of environmental impact, but the overall picture is nowhere near as bad as that argument makes it out to be.

mogur said:

Before we got our last car, I considered the Prius and did an evaluation to see what the economic breakeven point would be for me, comparing it to the other car we were considering (which got a real world 23mpg city and 30 mpg highway). I ignored any environmental concerns for this comparison. It worked out that I would have to drive 140,000 miles to break even. Long story short, we bought the other car.

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I am curious what assumptions you used in your calculations. Using simple math and todays average of $4 a gallon and 50 real world miles average of the Prius 140,000 miles worth of gas would cost $11,200 while using an average of 26.5 miles would cost $21,132 so a difference of $9,932. This is real simple math of course and does not include any maintenance cost assumptions between vehicles, inflation/deflation, gas prices over time or other monetary factors.

aqn said:

That's what I say to people to trot out the "but your new car required a lot of energy and resources to build than keeping your old car" line. That's only valid if I junk my current car. Rather, my current car is going to someone who is most like getting a newer, more efficient, car than his/her current car. And ditto that person's car. So I'm actually improving the overall efficiency/greenness of mankind's fleet!

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Not really true for a car that gives just 20 mpg.

Let us look at what actually happenned. When I had to sell my Maxima recently I had to discourage some people from buying it specifically because of its low mpg. Finally I sold the car to a college student (his dad bought it), who would have been equally happy to have got a 30 mpg small car. Maxima replaced a totalled car that was more efficient. May be his dad would have spent a little more and bought that smaller more efficient car if I wasn't selling.

Buying ANY new car is more expensive over the life of the car than buying a good used car. And it is unlikely that putting a used car on the market will prevent the buyer from buying a new car, since people who buy used cars are disinclined to buy new cars for the reason just mentioned.

Overall, for the nation or the world, less energy would be used if everybody kept their cars for an additional year, since fewer new cars would be built; but more pollution would be produced, as newer cars pollute less.

In general, whether calculating cost of personal transportation or carbon footprint, the used car or keeping an older car longer, is the better choice, and bring an ADDITIONAL car into your family when you can make do with your present car(s) is more expensive. But we are a consumerist society and very little that we buy is really necessary. We could live equally-long, equally-healthy lives if we cut our living space in half and lived bicycling distance from work. In fact, we'd probably live longer, healthier lives if we all bicycled to work.

I drive electric because I ENJOY driving electric. One diving trip to the Caribbean probably cancels out the carbon savings of ten years of driving my little Zap Xebra instead of the stinker.

daniel said:

In fact, we'd probably live longer, healthier lives if we all bicycled to work.

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Depends on where you live! I tried biking to work a couple times, and just about got creamed every time. Seattle drivers are idiots when it comes to watching out for bikes. Unfortunately in my neck of the woods, I think biking to work SHORTENS your lifespan! :shock:

But if EVERYONE did it, there wouldn't be that concern.

Oh, the other problem with biking is that you can't be talking on your cell phone while drinking your starbucks and working on your laptop while putting on make-up and messing with your radio all at the same time, like you can so easily while driving a car... :roll: (which, as it so happens, is the reason why in Seattle biking reduces your lifespan)

Back to being serious and more on topic, the other possibility is public transportation. My normal routine is to take my kid to daycare in the morning (3 mile drive) then go to the park-n-ride (4 mile drive) and take the bus in to work (10 miles the way I would go, 12 miles the way the bus goes). Now this is where I think a small EV (like a Zap Xebra or NEV) has a huge advantage. For a 7 mile drive (home to daycare to P&R) with a break in the middle, an ICE never gets up to temp. When I'm doing this commute in my ICE (granted it's an SUV) my mileage is pitiful at about 14mpg MAX (normally around 19mpg). My Xebra doesn't care, and actually is better when it's "cold" because the cooling fans don't have to come on. The Leaf? Even better, because it's so much more fun to drive, but is serious overkill for our general commuting needs.

The whole point being that as the trips become shorter, where a larger percentage of the time is before the ICE gets up to normal operating temps, EVs/PHEVs become an even larger benefit. Both my wife and I have very short commutes because we usually take the bus (more because it sucks to drive and park rather than being environmentalists). For our lifestyle, a PHEV that gets even 15-20 miles of pure EV range before the ICE kicks in would probably be ideal, assuming that it didn't carry a $40k price tag like the Volt. That would allow us to do about 95% of our driving as pure EV, while having the longer range of the ICE when necessary and keeping the price of the vehicle relatively low. If Toyota would have done this with the Prius, we would have bought it many years ago. The problem is perception of the general public. How do you convince the masses that 20 mile EV range is adequate and worthwhile?

And now as my babbling comes all the way full circle back to the original topic at hand, I wonder how you would go about calculating the carbon footprint of that kind of vehicle, matched with a particular driving style? It'd be interesting to play with various numbers to plug in your particular driving needs and different vehicle types (EV + separate ICE for longer trips, PHEV for everything, regular hybrid for everything, gas vs diesel, etc) and somehow be able to compare both overall pollution output and economic impact of the different choices.

(by the way, to comment on one of the other posts in this thread considering the carbon footprint to produce the electricity, if you're going to take that into account then on the ICE side you have to also account for the refining process and trucking the gasoline to the stations, which is a topic that has been beaten to death on other threads in this forum)

blorg said:

daniel said:

In fact, we'd probably live longer, healthier lives if we all bicycled to work.

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Depends on where you live! I tried biking to work a couple times, and just about got creamed every time. Seattle drivers are idiots when it comes to watching out for bikes. Unfortunately in my neck of the woods, I think biking to work SHORTENS your lifespan! :shock:

But if EVERYONE did it, there wouldn't be that concern.

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That's why I said "... if we all..."

blorg said:

For our lifestyle, a PHEV that gets even 15-20 miles of pure EV range before the ICE kicks in would probably be ideal, assuming that it didn't carry a $40k price tag like the Volt.

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Sounds like you'd be a good candidate for the Plug-in-Prius, expected to debut next year. (People have already gotten to drive a test version for a week at a time, IIRC.)

The other car, comparably equipped - actually better equipped and much more "fun" than the Prius - was $8K cheaper when real world selling prices were factored in. Also, gas was cheaper then so you would have to use a sliding scale to get a real cost analysis, which would decrease the differential you cited. The HOV stickers were sold out at that point so that was not a consideration, though, if they had still been available, that may have tipped the equation. One also has to factor in that I get to write off my gas and vehicle as part of my business... The numbers simply did not work for the Prius in my case and I honestly, found the car incredibly boring...

Spies said:

mogur said:

Before we got our last car, I considered the Prius and did an evaluation to see what the economic breakeven point would be for me, comparing it to the other car we were considering (which got a real world 23mpg city and 30 mpg highway). I ignored any environmental concerns for this comparison. It worked out that I would have to drive 140,000 miles to break even. Long story short, we bought the other car.

Click to expand...

I am curious what assumptions you used in your calculations. Using simple math and todays average of $4 a gallon and 50 real world miles average of the Prius 140,000 miles worth of gas would cost $11,200 while using an average of 26.5 miles would cost $21,132 so a difference of $9,932. This is real simple math of course and does not include any maintenance cost assumptions between vehicles, inflation/deflation, gas prices over time or other monetary factors.

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Thanks for sharing mogur. I suspect your ability to "write off my gas and vehicle as part of my business" can have a huge impact. I actually faired quite well with my Prius financially since financial government incentives were still in place as well as the HOV stickers. I actually purchased a new 2004 prius to replace the Honda EV Plus when it was taken away and I was able to sell the prius 2 years later for more than I payed and bought a new 2006 prius and came out with cash in pocket after the incentives. I am sure that was not typical for prius owners though. Hopefully I will be able to do the same with the Leaf

That may may give you a no-carbon footprint, but it doesn't change the overall carbon footprint of your region. The green resource that produces the electricity you buy isn't going to be turned off and let sit idle if you don't specify green - it will still run, same as otherwise, and the 'credit' for it will go somewhere else.

evnow said:

We have pretty green power in NW - and I specifically buy "green power".

- there is no carbon footprint for the electricity the EV uses. I guess that could be almost true if your utility uses only nuclear and renewables, but that is rare. This would tilt the calculation more toward the Prius.

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aqn said:

That's what I say to people to trot out the "but your new car required a lot of energy and resources to build than keeping your old car" line. That's only valid if I junk my current car. Rather, my current car is going to someone who is most like getting a newer, more efficient, car than his/her current car. And ditto that person's car. So I'm actually improving the overall efficiency/greenness of mankind's fleet!

At the very least, my car will be replacing someone else's current car, so yes, my new car is not free in term of environmental impact, but the overall picture is nowhere near as bad as that argument makes it out to be.

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This idea reflects my disappointment with the Cash for Clunkers program. In the C4C, dealers took in "clunkers" and were then required to have then destroyed, regardless of the value of that vehicle. A more well thought out program would have allowed folks could not afford a new car in the C4C program and had a real junker to exchange (for some fee?) that car for a better, higher MPG vehicle that came in through the program. That would have ended up removing a larger carbon footprint, helped more people, and people from a more varied economic backgrounds, and kept safer cars on the road.

As you well point out - it takes a lot of energy and resources to make a car. Why not try to keep the better of those on the road rather then mandating the trashing of perfectly good cars when there are still many cars on the road in need of major repair.

Yodrak said:

That may may give you a no-carbon footprint, but it doesn't change the overall carbon footprint of your region. The green resource that produces the electricity you buy isn't going to be turned off and let sit idle if you don't specify green - it will still run, same as otherwise, and the 'credit' for it will go somewhere else.

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Only if looked at in the short term. In the long term, more and more demand for green power will cause more green infrastructure to be built. Almost nothing we do as an individual amounts to more than a drop in the bucket. You have to turn it into a movement for it to have a big impact.

LakeLeaf said:

This idea reflects my disappointment with the Cash for Clunkers program.

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I always thought Cash for Clunkers was all about helping the auto industry sell more cars with a little greenwashing polish thrown on to make it more appealing. Of course this is just my opinion and somewhat off topic.

You also should take into account the "Hybrid effect". The early adopters that first bought hybrids blazed the trail for everyone else, just as LEAF owners are doing now. Hybrids are now no longer a niche vehicle, and their popularity has spurred battery technology, and probably even resulted in the development of the LEAF (definitely the Volt, as it's a Hybrid too.)

When my friends ask me for advice, I always (used to) tell them to buy a Hybrid if they can, because even if you personally don't benefit directly right now, you probably will later. If you have kids, they definitely will!

Now, of course, I recommend the LEAF were it makes sense. Toyota's version of the Plug-In Prius comes out later this year, and I will be recommending it as well.

I recommend the Prius often as it's one of the best engineered cars ever made in my opinion. Some may think it's boring, but with a few simple mods I think they are fun to drive and have many non-obvious benefits.

I don't commute, and like to take a handful of longish road trips each year, so a LEAF doesn't make sense. Instead I converted my 2008 Prius to plug-in with a 40 mile range. Did it make sense? Depends on which way you look at it. I know I'm doing my part for the future, and I've convinced many people over the last 5 years to buy Hybrids, with the majority being Prius. Everyone loves their choices!

I suspect fuel prices will continue to rise, then it really makes sense! If you make the choices to back the companies and technologies that will benefit us all in the future, you aren't making a bad choice regardless how the financials work out short-term.

-Phil