Thermodynamics of modes of transport: Cycling vs EV's

[SageBrush]

There are a couple other aspects of this that deserve mention. As a group, people that are physically active as a lifestyle -- not exercise per se -- weigh considerably less than their sedentary cousins.

A Kg of adipose tissue has about 7000 kCal of stored fat energy and requires about 13 kCal a day to maintain.

If we take 15 Kg as the average weight difference between the groups, the fat group has 105,000 kCal = 105*4.184 MJ of excess stored energy and eats extra food to to the tune of 300*4.184 KJ a day for maintenance.

So bicycling is more than free.

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Second, people do not eat sunshine and cars do not run on crops unless they are converted first to something like ethanol. So we can point out the ~ 20ish efficiency of humans in turning food into mechanical work but that same efficiency hit occurs when we turn crops into electricity.

 

[cvrcv]

There are a couple other aspects of this that deserve mention. As a group, people that are physically active as a lifestyle -- not exercise per se -- weigh considerably less than their sedentary cousins.

A Kg of adipose tissue has about 7000 kCal of stored fat energy and requires about 13 kCal a day to maintain.

If we take 15 Kg as the average weight difference between the groups, the fat group has 105,000 kCal = 105*4.184 MJ of excess stored energy and eats extra food to to the tune of 300*4.184 KJ a day for maintenance.

So bicycling is more than free.

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Second, people do not eat sunshine and cars do not run on crops unless they are converted first to something like ethanol. So we can point out the ~ 20ish efficiency of humans in turning food into mechanical work but that same efficiency hit occurs when we turn crops into electricity.

Can't say if the former is true, but it doesn't matter. You conclusion violates the first law of thermodynamics. Otherwise you could build a free perpetual energy machine from bicyclists.

 

[SageBrush]

You conclusion violates the first law of thermodynamics. Otherwise you could build a free perpetual energy machine from bicyclists.

You misunderstand the argument.

Fat has a dally energy cost to maintain.
Fat is stored energy.

 

[cvrcv]

You misunderstand the argument.

Fat has a dally energy cost to maintain.
Fat is stored energy.

No I get it. You're saying people ate way too much and are so fat anyway that they might as well get on a bicycle. So they've already committed the pollution they just need to cash in now? Like being in a bank you are robbing, all you have to do is walk out with the cash now?

How about we don't rob the bank.

 

[SageBrush]

How about we don't rob the bank.

That is not a helpful analogy.

A sedentary lifestyle has energy costs. THAT is the point.