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Are electric cycles greener than ordinary cycles?

Discussion in 'Earth and Environmental Science' started by Yellow Fang, 21 Jul 2011.

  1. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    I have just been reading in a book called "The Bottomless Well" that driving around in a big f***-off SUV is actually more environmentally friendly than cycling. It says,

    "Yet however preposterous the idea may sound, drilling for oil and building an SUV-grade highway system uses 10 times less land, per mile and per useful pound moved, than growing food to fuel a bicyclist. The SUV starts out 300 times worse than the bike - because it moves 30 times the weight of the its driver in steel, and because it needs 10 times more road-way per useful pound moved. In terms of land surface occupied to extract and deliver the energy used, however, crude oil is at least 1,000 times more frugal than grain. And a car engine, and the refining and distribution systems behind it, are about twice as efficient in converting crude oil to locomotion than the grain-bread-muscle systems that stand between plants and pedals on a bike; make that 16 times as efficient if the biker favors meat."

    Hmm, I'm not sure I buy that.
     
  2. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    I guess that works only if the SUV driver does not eat anything.
     
    rusky likes this.
  3. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    OK lets try and get some real science behind this.

    Firstly everything depends on how far you travel.

    If you have an suv and rarely use it, you would never build up the km's to be more environmental more friendly, if it is proved to be the case.
    Likewise there are optimal journeys you can do on a bike. If you try and do 100,000 km like a car can easily do then you are indeed going to burn quite a few extra calories.

    So lets set a benchmark. We will compare journeys which a bike can do in 1 hour to emulate a ½ hour trip to and from work 5 days a week. To accurately calculate this you need to take into account the fact that there will be two journeys with an 8 hour break between the two.
    We will also assume the journey is 1/3 uphill, flat and downhill for both.
    We will also assume for both that there are 4 stop starts to emulate traffic and crossings on each journey which makes 5 legs of the journey.
    We will assume both spend 5 minutes stopped in traffic each way.
    We will also assume the distance between each stop is equal.
    Finally we will assume each leg is equal in terrain with a flat start uphill, downhill then flat again.
    With the incline/ decline at a constant 5% gradient.

    So you can see already there are a lot of variables.

    To put this into some sort of equations you would have the energy consumed equal...

    For cyclists
    2 x ( ( 5 x energy used to cycle for each leg) + (4 x energy used while stooped) )

    For the car
    2 x (( 5 x Energy used while driving) + (4 x energy used while stationary) )

    For the driver
    2 x ( (5 x energy used driving) + (4 x energy used while in the stationary car) + energy used sitting down waiting for the guy on the bike to turn up )

    You could go really deep in and take into account things like the car warming up and becoming more efficient and the cyclists becoming tied towards the end. The road conditions. Energy for wear and tear on both the car and bike and replacement parts. Energy used traveling to and the physical act of refilling the car.

    Then of course there is the total manufacturing cost of both the bike and car, which if you are being that anal you might as well add in the calories consumed by the workers who make and transport both too.

    But you could go on forever.

    Now lets look at the calories.

    I'm not sure how many calories you consume on a typical bike ride of half an hour over varied terrain with a few brief stops. Whatever it is you would have to compare it to the amount you burn in the same time driving a car for the same distance the bike would cover. We will imply that you are sitting down for the rest of the hour to produce maximum difference. Although most people will still exercise to stay fit so this is not fully representative.

    So the maths here are

    Calories burnt by cyclists - calories burnt by driver = extra calories consumed.

    Quick science lesson: Different types of calories...

    http://www.mymoneyblog.com/what-does-200-calories-cost-the-economics-of-obesity.html

    You going to tell me they all take the same amount of energy to make?

    Obviously the way you put back the extra calories consumed will vastly affect the environmental cost. If you can do it with a few apples all grown in your garden. Well then it will be 0 providing you would not have eaten those apples or had the apple tree if you didn't have a bike. You could quite easily use something like locally produced potatoes to boost up using little resources. This all depends on how big the number of actual extra calories you do consume.

    One of the big environmental cost of food is transport which could be going electric soon. Already you have some of the last mile deliveries, like supermarkets, experimenting with electric vehicles. There are people looking at using sails, wind and solar combinations to part power huge transport ships. It can't be long before someone cracks a better way to do hgv's to. Then it's just the matter of clean energy generation and cleaner batteries. Though it appears at the moment eating local food is probably going to be better for the environment than what you drive.

    So the final sum is

    (Energy used to supply you a typical calorie x extra energy used) - (energy used to produce car - energy used to produce bike)

    If the answer is negative the bike wins, if positive then car wins.

    ..... Dam forgot to include energy used to produce the cars fuel and the environmental pollution from the car exhaust... and probably a lot more...

    It's one thing to state a fact. It's another to show your workings.
     
  4. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    I thought you were going to do the workings.

    The writers of the book were arguing that powering society by carbohydrates in terms of muscle power, human and animal, would require more land to be given over to agriculture. Apparently in America, the forests have been growing back since they've moved from horsepower to hydrocarbons, so despite their high per capita energy consumption, the US is still a net carbon sink. I'm not sure I believe this.
     
  5. amusicsite

    amusicsite dn ʎɐʍ sᴉɥ┴ Staff Member

    Location:
    UK
    Give me time :cry:
     
  6. Yellow Fang

    Yellow Fang Veteran Geek

    Location:
    Reading
    I cycled up to the wind turbine on the outskirts of Reading this morning. Indeed, there was an electric car charging point there. There was not an awful lot to see. There was a green thing with a solar panel on top. You swipe a card over one of the sensors and I guess a compartment hinges open; otherwise I could not see where you would insert the plug.

    Disappointingly, the turbine's electronic display was still boarded up. I also noticed that the Zephyr Airdolphins that used to be on the MacDonalds in the close by retail park had been taken down. Micro-wind has a reputation for being more trouble than it's worth, but at least those things used to spin around a lot. They must have been generating some useful electricity. The turbines were called Airdolphins because apparently the rudder was inspired by a dolphin's tail. They were used as an example in the biomimetics module in our Renewable Energy MSc.