Energy to build a car?

Discussion in 'General' started by Ebeo1, Dec 21, 2008.

  1. Ebeo1

    Ebeo1 Member

    Looks to me like a number of people here have traded in there vehicles for a more economical and ecological ride. I can understand there is a lot of immediate gain when comparing an I4 compact car to a monstrous V8 truck at the gas pump and exhaust pipe. When a car is built there must be an enormous amount of energy that goes into the harvesting of the natural resources, processing, transporting, manufacturing, and toxin by products. The more non-immediate gains to the earth by keeping your current vehicle must by far out weigh buying a new one.

    I know this not a black and white argument but a 1997 car getting 25 mpg must be more "earth" ecological from all the factors stated above than a new 2009 hybrid getting 65 mpg. The average American switches cars every 4 years so in the 1997 vs 2009 if you were to buy a new car every four years you would have gone through three cars and all the energy to get them to your local dealer. A little old grandma driving her 1988 V8 oldsmobile 4 times a week and the hypermiler commuting 60 miles daily might burn the same amount of gas but is the negative effects to the environment from combustion enough to warrant grandma buying a new car?

    How much energy does manufacturing a new car take?

    How many gallons of gas do you need to save before this number is off set?
  2. donee

    donee Well-Known Member

    Hi Ebeo1,

    Argonne National Labs and other researchers (specifically at MIT) have evaluated this issue.

    The Prius specifically was evaluated. Here is the two-bit description of the research results. Typical cars used 20 % of their total life cycle energy for production, and consumed nearly all the remaining 80 % as fuel energy. The Prius requires about 1.5 times as much energy to make as a standard car of the same passenger capacity (4 adults). But, it uses about 1/2 the energy to operate. So, using percentages of a standard car, that is 30 % to produce, and 40 % to operate, for a total only 70 % of lifetime energy consumption of a standard car the same size. Another way to look at it is the balance point, how much lifetime of the cars is when they have consumed equal energy. 10% extra energy is used to make the Prius. If 80 % of standard car energy consumption is used in 125K miles of operation , and the Prius uses 40 % of the standard car total energy to operate for 125K miles, then algebra can be applied. It works out to 31.25K miles. Both cars driven that far have used the same total amount of energy. After which the Prius will use less energy than the standard car. The extra energy to make the Prius is totally recouped on only 31.25 K miles of operation. Since the Prius lasts 125K miles (at least), then 93.75 K of those miles the car has used less total energy than a standard car.

    Its apples-to-oranges to compare the short range grandma Olds to the long range Hypermiler. As the grandma typically does not generate as much total product for society in that same week. I am in the 50 miles (daily) comute sitatuion. I use about 4.5 gallons of gas per week in my Prius. Grandma driving short distances, is not getting that big cast-iron V8 warmed up, so probably gets 10 mpg (15 mpg warmed up). If she were to drive more than 45 miles in a week, she would be using more gas than me in the same period. That equates to a 11.25 miles for each of those 4 days. 45 miles is less than 1/5 the distance (.18 actually) I get on the same gas. So by these numbers, I can use less energy, and dispense less CO2 in my Prius driving 250 miles a week, than grandma in her Olds V8, if she drives 45 or more miles each week. The numbers would be allot different if grandma was driving a Ford Focus - maybe grandma can drive 100 miles per week (25 miles a day) before she polutes more than me.

    Additionally, not all jobs are available in every neighborhood. But all jobs need to be done. So, people end up communting some distance not because of the desire for an inexpensive luxury house, in a town with good schools, but some end up in a situation where moving would be more energy intensive, let alone expensive, than the longer commute. In the end, there is no excuse for any of us, in whatever driving range to not be careful about what resources we use, and act to minimise that usage.

    The 1997 car is probably more ecological only if one assumes its life cycle is over, and one is remanufacturing the car, and only using the remanufacturing energy against the original production energy of the ecological car. The remanufactured 1997 standard car will be cheaper, because, well the dollar bought more energy of production in 1997, and remanufacturing uses allot less energy and very small fraction of the original materials. But cheaper does not mean more ecoological in this situation. If you compare the original 1997 production energy and fuel consumption, against the 2004 Prius, well, the Prius is more ecological. If the 2004 Prius was made in 1997, one would see this clearly.
    Last edited: Dec 21, 2008
  3. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    To quote a prominent phrase here on the site, "Learn to raise fuel economy and lower emissions in whatever you drive" -- loosely translated by some members as, "Dance with the girl you brung." ;)

    Your point is well taken in that in many cases you are better off doing what you can with what you have (considering environmental impact), and that is pretty much what I've done with my '02 Elantra (last tank at 65.2mpg). I did buy an Insight nearly a year ago, but I can't justify that in terms of cost savings. For me the car was definitely a "want" purchase, but two things tempered that. First, the car is actually worth more now than when I bought it and it will continue to retain or even appreciate in value as the price of fuel rises. Second, if things get really bad, I'll still be able to afford to drive when many may not.

    I do have plans to get another vehicle in the next several years, but the point of that purchase would be a full electric vehicle with long AER which I would then keep for much longer. I expect both my vehicles to be over 10yrs old by then and to have been hypermiled to way lower consumption values than the average driver would accomplish with either.

    As Donee pointed out though, there are valid reasons for purchasing a more efficient vehicle. Aside from the reasons he listed, there is also the increased safety equipment and reliability aspects to consider. This is why I sold my '95 Elantra back in '02 and bought my current Elantra (which is holding up WAY better than that vehicle did, I should add).
  4. peacefrog_0521

    peacefrog_0521 Raj Against The Machine

    I think this is a very interesting question, though I must admit it's a bit bit academic, much like question of whether greenhouse gas emissions through the use of plug-in hybrids are increased by shifting the emissions from vehicles to powerplants.

    And as a caveat: if we bought based on which manufacturers were most efficient, we'd all be buying Chrysler vehicles. They were found to be the most efficient manufacturer (even more so than Toyota or Honda) in terms of hours per vehicle.

    I doubt anyone would buy the argument that one is "going green" by driving a Chrysler ...
  5. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    ___Here is Toyota's numbers for North American production as I am doing a write-up on their 08 Environmental report currently...
    ___Good Luck

    Last edited: Dec 23, 2008
  6. NiHaoMike

    NiHaoMike Well-Known Member

    But what kind of energy is used? Obviously, solar or hydroelectric power would be less of an impact than fossil fuels.
  7. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi NiHaoMike:

    ___That is the average and changes as a given plant or non-production facility receives more renewable energy inputs as time goes by. Reading deeper into the 08 Toyota report, the number appears to be more along the lines of 6.9 MMBTU/vehicle produced through the end of this year.

    ___Good Luck

  8. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    ___I still have a few more hours on the Toyota Environemental Report synopsis before it is ready but here is the energy consumed per vehicle from Toyota directly. I hope this helps...


    ___Good Luck

  9. jkp1187

    jkp1187 Well-Known Member

    Donee, that's very interesting. Do you have a citation or link for this study?
  10. some_other_dave

    some_other_dave Well-Known Member

    I'm having fun hypermiling my 1990 model year car... :)

    I'm only capable of around 40 MPG so far, but that's still 30%-50% better than most new cars driven by "average" people, so I figure I'm pretty far ahead on the game there.

    Plus it's been paid for, and has been for many years.

  11. Chuck

    Chuck just the messenger

    In the flawed Dust-to-Dust "study", there was a question of the percentage of energy used to make a car in relation to it's entire life....think it's no more than 15%.
  12. basjoos

    basjoos Well-Known Member

    Ditto for my 1992 Civic, which, as aero modded, gets better highway mileage than any new car currently being sold. Plus its been paid for since 1996, didn't have the added hybrid manufacturing energy costs, and is still rolling after close to 500,000 miles. So its been very energy effective to keep on driving it.
  13. Shiba3420

    Shiba3420 Well-Known Member

    The original quesiton sounded like a ecological choice, not economic. As such, consider that buying a new car doesn't make the old car go to the garbage heap...if it does, it probably needed to be replaced. Someone else will take advanatage of the rest of that car's life, so the numbers are far more complex that what we have yet. As long as every car does get to live its complete life, then you never really have to worry about energy production as a reason not to upgrade. However, we probably should consier energy production when we purchase a new car. I believe someone said the Prius takes about 1.5 times the energy to produce from a typical car, however that additional energy up front results in less energy usage on the much longer back end. If however a lux car also took 1.5 times the energy to produce, but you only got better wood, leather, and electronic gizmos, then the addtional energy would be wasted in terms of ecology.

    What would be interesting is if there could be an incentive to buy & crush old cars when they reach a point where getting the old vehicle off the road would results in better ecology than the damage caused by trading up to a cleaner new or used car.
  14. donee

    donee Well-Known Member

    Hi jkp...,

    Allot of that was off the top of my head, from what I remember reading on the net.

    Here is a link to the Argonne GREET , which is a model of energy consumption:

    I cannot find the references to the MIT work at the moment. They were originally secondhand to start.

    There is a Google Answer to vehicle production energy. Here is a link to that:

    In there they conclude based on an Argonne report:

    Page 9 of the report initiates the coverage of assembly and recycling energy.

    One estimate cited is that it takes about 3.8MJ/kg to recycle a
    vehicle and the report attributes about one-third of this to
    electricity. Environmental impact will depend a lot on the source of
    the energy used in recycling.

    The Argonne National Labs study also estimates the primary consumption
    of energy in the lifecycle of a mid-sized passenger car (about the
    same weight as the full-sized Ford pickup you mention) at 867GJ of
    primary energy as fuel (gasoline).

    Manufacturing and recycling costs for assembly as well as materials
    production are about 79 GJ, or about 8 percent of the direct engine
    fuel consumption.

    YOU INITIALLY ASK, 79GJ of energy to manufacture AND recycle a vehicle
    at the end of its useful life. The recycling cost is about 3.8MJ/kg
    times 1500kg vehicle weight or 5.7GJ. That makes the total
    manufacturing cost for an average passenger vehicle or consumer-type
    truck about 73GJ.

    8 % is somewhat smaller than the 20 % I used. Thus the mileage at equal energy consumption will be somewhat less than I estimated.
    Last edited: Jan 2, 2009

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