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A gallon of gas has 30,000 Calories. An SUV weighs (technically masses) 2000kg and gets 20 MPG. Thus the kilogram miles per Calorie -- the efficiency -- for an
by WildUtah 14y ago
A gallon of gas has 30,000 Calories. An SUV weighs (technically masses) 2000kg and gets 20 MPG. Thus the kilogram miles per Calorie -- the efficiency -- for an SUV is 1.33.
A peanut butter sandwich is 600 Calories (with bananas and maple syrup on whole wheat, but corn syrup on Wonder bread is similar). A bicycle plus messenger bag and rider weighs 80kg and gets 10 miles to the peanut butter sandwich. Thus the efficiency of the bicycle is 1.33 kg.mi/C.
So far the bicycle and SUV seem exactly equal in efficiency and have equal environmental impact.
But that doesn't take into account cost. The peanut butter sandwich costs $5, or $3 if you make it at home. Call it $4. The gallon of gasoline also costs $4. But the gasoline has 50x the energy. The total cost to society is 50x higher to operate the bicycle, taking all process costs into account through the price system.
So in fact, biking is terrible for the environment. We'd all be better off banning bicycles and buying every cyclist an SUV and then having a mass lycra bonfire. Plus, think of all the cash we would save by not blowing it on extra bicycle fuel. It could save the economy.
- karanbhangui 14y agoIsn't 1 food calorie equal to 1000 physics calories?
- epochwolf 14y agoYes. Food calories are actually kilocalories.
- tolmasky 14y ago1 Calorie = 1000 calories. Yes, the unit is differentiated by capitalization.
- pjscott 14y agoAnd for the sake of preventing further confusion, it's probably best to promptly convert that into a sensible unit: 1 Calorie = 4184 Joules.
- Trezoid 14y ago10 miles seems pretty low to me. I can easily get double that giving it 2.66 kg.mi/C
- tomkinstinch 14y ago> But the gasoline has 50x the energy. The total cost to society is 50x higher to operate the bicycle I know your comment was tongue-in-cheek, but energy content =/= cost to society. The health benefits alone of cycling make it a net win given current costs.
- WildUtah 14y agoMedicare kicks in and absorbs all medical costs at social expense beginning at age 65. Cyclists seldom die before 65, so that is a social cost. Cycling has known cardiovascular side effects. As a result cyclists seldom die suddenly of heart disease, the cheapest of the common ways to die. Another social cost. Everybody dies of something but cyclists are proven to live much longer and consume extensive social resources in their lingering. Triple social cost. The ideal health policy for our nation's fiscal health is to tax cyclists and use the cash to buy cigarettes for young people.
- brc 14y agoYou forgot to include the economic cost to production that occurs when a bicycle courier ends up beneath an SUV. This delays delivery from the SUV, unnecessarily uses up emergency services, and moves delivery onto other, inefficient bicycle couriers who have to take up the slack while the original spends 6 months in hopstial.
- rdouble 14y agoMy peanut butter and banana sandwich costs less than 75 cents, and I buy the fancy bread and peanut butter.
- Justsignedup 14y agoIncreasing efficiency... And fuel prices keep going up. And if we stop subsidizing they will double or tripple.
- jonemo 14y agoIs this meant to be ironic or am I totally missing something? Sure the kilogram miles per Calorie look similar, but as you noticed the SUV is a lot heavier than the bicycle. You should only include the weight of the payload, i.e. the passenger, in the calculation because that's what you want to move. Having to move an additional 2000kg of SUV around is what makes SUV-driving so inefficient.
- mistercow 14y ago>Is this meant to be ironic or am I totally missing something? I think if you note the claim that a homemade PB&J sandwich costs $3, as well as the reference to "extra bicycle fuel", you will have your answer.
- sliverstorm 14y agoYou are correct, if you are talking only about pure efficiency. Your parent was talking about (ironically or not) cost. At current market rates, peanut butter is inarguably a more expensive fuel per Calorie than gasoline.
- witten 14y agoNot to mention that a bike's wear and tear on the road is exponentially less than the damage incurred by a passenger car or SUV: http://en.wikipedia.org/wiki/Gross_axle_weight_rating http://en.wikipedia.org/wiki/Gross_axle_weight_rating
- DanBC 14y ago> A bicycle plus messenger bag and rider weighs 80kg wait, what?
- delinka 14y agoYou forgot to consider the production process of the SUV versus the bike.
- ojbyrne 14y agoExcept that you have to assume the person driving the SUV eats too.
- ars 14y agoHe's only including the extra calories, not the baseline.
- Justsignedup 14y agoRemember when we say food Calories, we actually mean kilocals. HOWEVER, while fuel itself may be more efficient to move, you always end up moving a very heavy item (the car) thus you always do better by not moving the car. AND that person inside it as well. However, we also must account in addition to fuel cost, the cost of the person breathing. A person's standard breathing vs ~ double for exercising. So a person sitting inside that SUV is already creating ~ half the CO2 that a biker would. Then the final note: Gasoline is a very finite supply. PB&J for all practical purposes is 100% renewable.
- MaysonL 14y agoInterestingly, a 2004 life-cycle analysis of energy costs came to the conclusion that electric bicycles were more efficient than human-powered (given average diet). http://www.ebikes.ca/sustainability/Ebike_Energy.pdf http://www.ebikes.ca/sustainability/Ebike_Energy.pdf