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Check my math - Tesla CO2 footprint

Discussion in 'Model S' started by Black/Black MS, Nov 18, 2016.

  1. Black/Black MS

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    I was doing a little research, and while definitive data was hard to find I found some statistics that stated that over its lifetime a gas car produces 24 tons of CO2, while an EV produces 19 tons of CO2 (taking manufacturing into account, etc.). I realize that those numbers could vary wildly by location, etc., but are they even remotely in the ballpark? At a cost of $10 per ton of carbon offset, that implies that the cost to offset buying a gas car vs. EV is $50. That doesn't sound right.
     
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  2. dhrivnak

    dhrivnak Active Member

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    I think that is off. One gallon of gasoline produces 19.50 lb of CO2. That increases to 24 pounds if you include refining which must be done. So if you assume the average car drive 150,000 miles over its life at 24 mpg I get 75 tons just for the fuel. Even a Prius at 50 mpg and 150,000 miles will produce 36 tons and that includes 0 for manufacturing.
     
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  3. Black/Black MS

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    That sounds a little more reasonable. I found this article, which making some rough calcs based on the graphs gives about 120 tons for a full size gas car. vs. 60 tons for a full size EV.

    Still makes me question, if the cost of carbon offset for buying a gas car is $600 (60 x $10), particularly when that comes at the expense of a $7,500 federal subsidy, what's the point? Why not plow that $7,500 into carbon offsets where it could be 10x more effective?
     
  4. bonnie

    bonnie Oil is for sissies.

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    It's unclear (to me, anyway) if your calculations included manufacturing for just the EV or for both the EV and the ICE.

    You also need to include the CO2 footprint of gasoline production and transport to delivery sites. And the manufacture of the trucks that deliver it (plus the CO2 they emit).

    Spoiler alert: It gets ugly really fast.
     
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  5. RogerHScott

    RogerHScott Active Member

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    Well, to be really fair you also need to include all of those same production and transportation carbon costs of whatever fuel is
    being burned to produce your electricity, if you're using fossil-fueled electricity. Even "clean" natural gas production is actually kind of
    carbon-dirty, since huge amounts of CO2 come out of the wells along with the gas and currently there's no practical way to do anything
    with it but vent it straight into the atmosphere. If you're burning coal from Wyoming in Illinois or Wisconsin it's being hauled quite a ways
    by a diesel-burning train to get there.
     
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  6. bonnie

    bonnie Oil is for sissies.

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    Yes, absolutely true. But you'll find that the miles traveled by a gallon of gas is slightly less than if you put that electricity into a Roadster battery directly. In other words, if you get 28 mpg for a gallon of gas, you'll travel further with an EV on the same electricity used to make that gallon of gas.

    Also, unlike the production of gasoline - the electrical grid is becoming cleaner every day, as old plants are retired, as solar is more widely adapted, etc.
     
  7. Black/Black MS

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    Even taking all that into consideration, say that you have a solar array and a green grid to power your Tesla, you're still only approaching something like $1k in carbon offsets to buy a Tesla vs a gas vehicle. How is it that purchasing a Tesla rather than purchasing a comparable car $20k cheaper and spending the savings on carbon offsets is not by far the better way to benefit the environment?

    I'm not concern trolling here, I'm a P90DL owner who bought my car because I think it's the coolest car on the market. I'm just trying to see how I can justify that as an environmentally conscious purchase.
     
  8. ecarfan

    ecarfan Well-Known Member

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    Powering an EV from a home solar system (as I am doing) is clearly far better over the lifetime of the EV and the solar system (which is very long) compared to powering an ICE when all factors are properly accounted for. One the solar/EV system is built it produces zero emissions for decades (yes a Tesla will likely last for decades). The ICE and the gasoline production/supply chain produces huge emissions over its entire lifetime.

    Powering an EV from sustainable energy delivered over the grid is still vastly preferable to powering an ICE.
     
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  9. RogerHScott

    RogerHScott Active Member

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    OP, if you believe that carbon offsets are fairly valued then the cost differential for a Tesla is not justified solely on the basis
    of its smaller footprint. But given that there are people who buy Teslas who don't really care at all about carbon reduction there's
    clearly value there in other areas. You certainly don't need a Tesla-class car to accomplish only the carbon reduction. But you
    do need it to accomplish a Tesla grin :)
     
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  10. JRP3

    JRP3 Hyperactive Member

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    Actually this isn't accurate. The energy used to create a gallon of gas is around 6kWh, however only a small percentage of that is electricity, less than 1kWh/gal. Most of the energy used is in the form of heat created by burning petroleum byproducts.
     
  11. bonnie

    bonnie Oil is for sissies.

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    Oh, I can help with this! :) I went through the same thought process after buying my Roadster. "I could have spent this same amount of money elsewhere and made a better environmentally conscious decision."

    But then the forum (@vfx, I think) pointed out to me that after purchasing it, I'd had numerous parking lot conversations about lessening our dependence on foreign oil, the need to reduce CO2 emissions, and how fun electric was to drive. And then when you add in the countless car events (some EV-specific, some not), Earth Day events, etc - I've had hundreds upon hundreds of those conversations. I know people here on the forum that were influenced to buy after seeing my Roadster. I have family and friends who have either purchased or who have a Model 3 reservation because of my advocacy.

    So if you're trying to justify, also factor in the ripple effect. And go buy your car. :)
     
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  12. bonnie

    bonnie Oil is for sissies.

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    Thanks, JRP3. You're right, of course. Still more effective. :)
     
  13. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    #13 ItsNotAboutTheMoney, Nov 19, 2016
    Last edited: Nov 19, 2016
    It's as simple as this to me: it is currently much more likely that a perfect energy supply (clean, sustainable, domestic and cheap) is possible with electric vehicles than internal-combustion-engine vehicles. And more than that, having more electric vehicles would directly and indirectly help us move towards that perfect energy supply.
     
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  14. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    So, let's be conservative and say the equivalent of 2kWh of electricity plus whatever we could do with that heat.

    Also note that the amount of energy required to produce the gasoline depends on the type of petroleum.
     
  15. somnambule

    somnambule Member

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    You should be comparing your P90DL to an ICE car with comparable size, performance, features, and brand image. I doubt that car is $20k cheaper.

    Regardless, you are investing in the early phase of the EV industry. Thanks to people like you, as the EV industry grows and matures, the price gap between an EV and a comparable ICE car should drop to the point where it's less than the cost of carbon offsets. But we'll never get there if no one bought EVs in the early phase we are in today.
     
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  16. Zapped

    Zapped Model S - PURE EV

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    #16 Zapped, Nov 19, 2016
    Last edited: Nov 19, 2016
    CO2 is one component.
    I tend to think of the pollution I am not creating while owning my EV.

    If a gas vehicle can kill you from the exhaust running in your garage for 10-15 minutes, just think of the thousands of cars emitting the same exhaust in our cities and neighborhoods polluting our atmosphere.
    IMHO, That alone is an indisputable environmental benefit of owning a EV

    You can breath easier knowing you own an EV
     
  17. abasile

    abasile Independent Software Eng.

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    Buying an EV is an investment in the future. As EV drivers today, we are helping to catalyze a massive shift that needs to happen.

    The only way to fully offset the continued burning of fossil fuels would be to develop technology to inexpensively extract and sequester huge volumes of carbon from the atmosphere. I don't see that happening anytime soon. So we do need to stop burning fossil fuels. And we also need better air quality. (Lest anyone protest that modern ICE tailpipe emissions are already clean enough, try standing next to any ICE vehicle that has just started its engine on a cold morning. They stink.)

    Eventually, with good policies in place, carbon offset prices should increase. But we shouldn't need to wait for that to happen.
     
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  18. jsmay311

    jsmay311 Member

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    I'm really heartened to see this discussion being had, since climate change is my main motivation for owning and advocating for EVs, while at the same time their actual environmental benefits are often exaggerated by well-meaning EV advocates.

    I think the answer to the OP is multifold:
    • As pointed out by others, your example lifecycle CO2 numbers are too low for both an EV and a ICEV.
    • That said, given how difficult it is to come up with a *consensus* estimate for the manufacturing energy of lithium ion batteries, you're not going to be able to agree on one definitive answer for this question anyway.
    • No calculation is ever going to show you that purchasing a $80k+ Tesla is an efficient way to spend dollars to reduce your carbon footprint, no matter how absurdly high you might set the price of carbon. Home energy efficiency, insulation, solar, wind, etc., etc., etc., will beat an expensive EV every time, hands down. Only an EV with a relatively small price premium powered by clean energy will look good "on paper". (And yet I know that, especially on a Tesla forum, I don't need to point out that not every decision comes down to an unimpassioned matter of dollars and cents.)
    • The price of carbon offsets and the actual social cost from an emitted amount of carbon are not the same. While you might find that the going rate for a carbon offset is ~$10/ton, the EPA estimates that the actual social cost of 1 emitted ton of CO2 is ~$37/ton. (Others argue it's far higher... over $200/ton: Estimated social cost of climate change not accurate, Stanford scientists say ) That's because an offset will be priced at the cheapest dollar amount at which you can pay someone to prevent or avoid the emission of 1 ton of CO2. (This "offset" can take many forms, some of which have questionable validity.) The actual (er, estimated) cost/damage from emitting that same 1 ton of CO2 has nothing to do with the cost of preventing that other 1 ton from NOT being emitted.
     
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  19. Lon12

    Lon12 Member

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    Exactly.
    I fly into LAX quite a bit and when you see all the cars and smog it makes you worry about the health of those living there. Even moving the "dirty" energy production away from where we live is critical.
     
  20. Topher

    Topher Energy Curmudgeon

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    Surely everyone has already done those things. If not, get on it people! There comes a point when the only remaining carbon footprint is local medium distance transportation, and an EV is one solution for that. $80k is a lot of embodied energy, luckily there is a $35k version soon (and that is still too high).

    The trouble with calculating harm in this way is that there isn't some safe limit per year that we need to stay under. It all adds up. Dropping our yearly CO2 output to 1990 levels, or 1980 levels, or even 1950 levels, just means we are killing our grandchildren slower.

    Thank you kindly.
     
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