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Motorcycles worse for environment then cars?

Discussion in 'General Motorcycling Discussion' at netrider.net.au started by ad91on, Oct 3, 2011.

  1. http://latimesblogs.latimes.com/greenspace/2011/09/mythbusters-motorcycle-emissions.html

    A trend is afoot, according to "MythBusters" television host Adam Savage: "People are trading in their cars and driving motorcycles instead because they believe that's the more environmentally friendly choice," Savage said in Wednesday's season opener of the popular Discovery Channel show. "The logic is because motorcycles are generally more fuel-efficient than cars, they burn less gas and thus they must be better for the environment."

    The question is: Are they really? As the MythBusters have done with each of the show's previous seven seasons, Savage and his co-host Jamie Hyneman set out to test the theory.

    Selecting three motorcycles and three cars that represented popular models from the '80s, '90s and '00s, they put the six vehicles through a 30-minute, 20-mile course. Seventy-five percent was freeway driving; the other 25 percent was in the city. Savage drove the three cars. Hyneman trailed him at speed on each of the three bikes. None of the vehicles' makes and models were disclosed.

    All of the vehicles were equipped with portable emissions-measuring systems that took exhaust gases from a probe in the tailpipe and engine information from the engine control unit. The devices determined the vehicles' fuel economy and emissions profiles while the vehicles were running on the real-world course in California's Alameda County earlier this year.

    The upshot? Motorcycles were indeed more fuel-efficient than cars and emitted less of the greenhouse gas carbon dioxide, but they emitted far more smog-forming hydrocarbons and oxides of nitrogen, as well as the toxic air pollutant carbon monoxide. For the most recent model year vehicles tested -- from the '00s -- the motorcycle used 28% less fuel than the comparable decade car and emitted 30% fewer carbon dioxide emissions, but it emitted 416% more hydrocarbons, 3,220% more oxides of nitrogen and 8,065% more carbon monoxide.

    The MythBusters' conclusion: "At best, it's a wash. Motorcycles are just as bad for the environment as cars," Savage said on the show. "At worst, they're far worse."

    "We've been working to clean up passenger vehicles since the '70s," said Kent Johnson, who's on the research faculty at UC Riverside and is director of its emissions lab, where the MythBusters' numbers were analyzed. "We've been putting on catalytic converters and sensors to improve their ability to control emissions. We didn't start doing that on motorcycles until the 2000s. It just shows you how far we've taken passenger vehicles and how difficult it is to do the same thing with motorcycles. First of all, there's no room. And the incremental cost might double the price of a bike."

    The California Air Resources Board, which had been approached to perform the emissions tests for "MythBusters" but couldn't because the tests it performs are stationary, concurs with Johnson's assessment about the added cost and technology burdens of placing greater emissions controls on motorcycles.

    While many modern motorcycles are now fuel-injected and equipped with catalytic converters and charcoal canisters to control emissions, they still pale in comparison to the emissions controls of cars. That point was made in a followup emissions test performed on the "MythBusters" season opener when Hyneman constructed an aerodynamic shell for a "late-model," 250-cc, single-cylinder motorcycle equipped with fuel injection and a catalytic converter.

    Without the aerodynamic shell that transformed it into the so-called "bubble bike," the motorcycle achieved 56.1 miles per gallon, but it ranked second-highest for carbon monoxide emissions and third-highest for hydrocarbons and oxides of nitrogen of all the vehicles tested during the show. The aerodynamic shell increased the bike's fuel economy to 70.9 miles per gallon, but its carbon monoxide, hydrocarbon and oxides of nitrogen emissions remained stubbornly high.

    "Our strategy with motorcycles has always been to control them to what's cost-effective and technically feasible, and that's always lagged behind cars," said John Swanton, air pollution specialist with the Air Resources Board. Emissions standards for motorcycles are, accordingly, more forgiving than they are for cars and will most likely stay that way since motorcycles account for such a small portion of vehicles on the road.



    The Air Resources Board estimates there are 600,000 motorcycles in active use in California, which account for less than 1% of vehicle miles traveled in the state. Those 600,000 motorcycles, however, account for 13% of the state's hydrocarbon emissions from passenger vehicles, Swanton said.

    "Our goal in regulating all vehicles is to retain the gains we've made in reducing smog-forming emissions because those have an immediate impact on the health of Californians. You are immediately impacted by ozone, whereas climate emissions are longer term," he said.

    While 90% of internal combustion engine emissions are carbon dioxide, a greenhouse gas, "To trade one emission for another is not the best strategy," Swanton said. "We've got to balance the two."

    In the 2011 American Lung Assn. State of the Air report, eight of the top 10 cities for ozone pollution were in California. Los Angeles ranked first.

    Despite the MythBusters' findings, emissions are only part of the story of a vehicle's true greenness. According to the Motorcycle Industry Council, motorcycle manufacturing requires thousands fewer pounds of raw materials than automobiles. They require less fossil fuel, so they require less energy to pull that fossil fuel out of the ground. They use fewer chemicals and oils than cars. And motorcycles produced today are 90% cleaner in California than they were 30 years ago.

    Note to MythBusters: How about a cradle-to-grave life cycle assessment for cars and motorcycles for the Season 9 opener?
     
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  2. easily fixed with a catalyst
    i call bullshit on the statistics. If they bikes are only emit 4 times more HC than other vehicles then they account for 4% of total HC emissions don't they?
     
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  3. Yeah, sounds like motorcycles are getting scapegoated for something.
     
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  4. I recall Honda claiming that for some US cities, their exhaust gases (VFR1200?) are cleaner than the air going in!

    I wonder what 'late model 250cc single cylinder with FI and cat' was tested?
    Hopefully not an RS250...

    "While 90% of internal combustion engine emissions are carbon dioxide, a greenhouse gas..."
    CO2 is the only game in town, really.
     
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  5. But motorcyclists shower a lot less - so it evens out right?
     
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  6. I wonder if they took filtering into account and the fact that a motorbike in peak hour traffic will spend half the time burning fuel than a car idling away for an hour on the same length commute.
     
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  7. The RS250 is a twin and was not really sold in the USA. They probably tested the cbr250r .


    Whole of life emissions would also be interesting as lots less stuff go into bikes, so less mining and refining etc. Though less life.
     
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  8. It was a Yamaha 250 trail bike, wearing road tyres.

    They chose it because it has fuel injection, small displacement, a catalytic converter and all the other emissions-control features they'd seen on modern bikes and therefore ought to have given the best chance at beating car emissions. Being a trailbike it'd be tuned for less drastic valve overlap (more bottom end power, less top-end power) and so in my mind that ought to help at well.

    With the bare bike they got 50mpg average; with the aerodynamic teardrop/bubble over it they got about 70mpg, but the hydrocarbons, NOx and CO were still pretty bad.


    If I had to guess I'd say part of the problem for motorcycles is that bikes run a _ridiculous_ amount of valve overlap because the engines are designed to crank out 120-180hp/litre rather than 60-80hp/litre. Even with a catalytic converter, charcoal canister and more, a metric shit-tonne of hydrocarbons and noxious gasses are going to be present from how much unburned fuel makes it from intake to exhaust when the bike's at lower revs and partial throttle.

    Edit: Actually, one disappointment with that episode was that they didn't talk about WHY bikes might hypothetically perform worse in terms of HC, NOx, CO, etc. Not even a glib comment like "There's no room for a proper-sized cat on a bike!" or discussion of how valve overlap lets a tonne of unburned fuel pass from intake to exhaust, etc. It was a straight-up test of the myth rather than exploration of the myth to educate and illustrate, like what they used to do in the past.
     
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  9. Win for BMW then :D. The old 2-valve K-Series bikes have precisely zero valve overlap. When I noticed that I wondered if the valve timing was to suit forced induction but now you mention it, emissions reasons seem more likely.

    Earlier posters are right, though. Emissions can't be considered in isolation. Whole of life, journey time, traffic congestion and general resource use (parking space is not environmentally "free" for example) need to be taken into account.

    There is also the point that passenger car emissions may now be approaching the limit of what is possible with the conventional four-stroke cycle, petroleum fuelled engine. Bike emission technology, however, is still improving rapidly.

    TBH, I've always thought bikes don't compare that well environmentally, but I don't believe that, as part of the bigger picture, they pull up quite as badly as a relatively superficial and limited test such as this shows.
     
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  10. One thing that wasn't considered is the travel cycle. Motorcycles spend far less time idling in heavy traffic than cars and have generally overall shorter travel times. This can mean significantly fewer emissions over a given trip.

    There's also no consideration of the fact that motorcycle manufacture may use fewer emissions and uses far less in the way of raw materials. There needs to be a lifecycle comparison to make it effective.

    An interesting paper from the University of California, Berkeley Centre for Urban Transport can be found here - the results vary depending exactly on which sort of emissions you are referring to. The chart below is from this paper (it's CO emissions only).

    CO emissions
    Emissions.
     
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  11. These brain dead environmentalists always judge how eco friendly a bike/car is just by how much fuel and toxins it spews out.............................why dont they ever do a life cycle study that includes material extraction, manufacture, disposal and the like..............
     
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  12. I don't see any environmentalists in that report, brain dead or not. Two TV presenters with, IIRC, movie special effects backgrounds, and two scientists specialising in air pollution related fields but no environmentalists.

    QUOTE].............................why dont they ever do a life cycle study that includes material extraction, manufacture, disposal and the like.............. [/QUOTE]

    Who, exactly are "they"? This was a quick and dirty test for the purposes of entertainment, not a peer reviewed research paper. The TV prog got their footage and their ratings, the scientists stated the bleeding obvious regarding bike emissions (whilst also being quite fair in recognising the limitations of what is currently practical) and some anonymous sub-editor at the LA Times wrote the headline.

    Whilst I'm not personally aware of any substantial, peer-reviewed papers on bike vs car environmental impact, I'm not immediately leaping to the conclusion that such don't exist.
    Indeed, what's this that TonyE has linked to? Could it possibly be a proper academic paper on such a subject? Why, yes it could. I'll download it and have a read when I'm not behind the firewall at work.

    Doesn't have the media pull of Mythbusters though.
     
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  13. The real question is, why didn't they mount the RPG to the bike :twisted:

    One for the bike spotters, which bikes were they using. The 80's bike looked like a Honda, not sure what the 90's and 00's bike were.
     
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  14. Ashamedly I wasn't paying too close attention to which bikes they used when I watched it.

    For what it's worth, their methodology to select a "typical" bike & car for each era was to choose an example of the most popular bike of the decade and pair it up with an example of the most popular car of the decade.
     
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  15. Lol speak for yourself
     
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  16. No wonder the bikes didn't perform well then. The typical bike is a sports or big cruiser compared to a economobile.
     
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  17. there's a study on the first page
     
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  18. Its much of a muchness. Advantages and disadvantages depending what statistics you pull.

    You could say, that per kg, the fuel usage/emissions is much higher on a bike. But you could also say bikes are more enviro friendly given there are less materials used.

    You could then focus on the fact that bikes aren't very aerodynamic, but the counter is the shorter travel times and less time in traffic. Compared to my car, the bike is about twice as fuel efficient. However compared to a modern light yaris or equivalent, the yaris would do just as well.

    Also, not everyone out there drives a small lightweight economical car. The statistics change if you choose a 125cc scooter that might use 3L/100km as well.

    So really, the mythbusters episode is more entertainment than science. All they can really say is that their findings are valid for the two vehicles they used - not across the board.

    Personally I know from a cost perspective, the bike costs just as much. Less fuel. But servicing is more often. Tyres are more often. No doubt other consumables are more often somewhere. I don't ride for efficiency though.
     
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  19. and then you have the 'per capita' numbers. As soon as there's more than one person in the car there's no contest
     
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  20. Horses for courses. I'd think that generally, for the transport of an individual and individual only, bikes on average would be cheaper.

    Consider that asian countries use motorcycles far more often... good reason for this
     
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