Ebike vs human rider = 4 time more energy efficient

[Doctorbass]

Back in 2004, Justin Elmore made a really interesting document about this:


The Energy Cost of Electric
and Human-Powered Bicycles

Every E-S members should read this at least one time!

This is really interesting to discover many other advantages have the ebikes over the rest of the transport.. more than we think!

http://www.ebikes.ca/sustainability/Ebike_Energy.pdf

Doc

 

[el_walto]

I don't really buy into this conclusion.

so a value of 1000 cycles for an electric
vehicle is reasonable

These figures take into account the transportation of raw materials to the
manufacturing plant. In addition, there is the transportation of the finished battery
pack to the end user

However the electric motor,
controller, and charger, are all maintenance-free with an indefinite life-span, so
beyond their initial manufacture there is little associated environmental cost. The
one component that does require replacing is the battery pack and this will be
included in all calculations.

For instance, the health
benefits and costs of exercise will not be addressed, nor will the disposal of toxic
materials in batteries be considered. Accounting for the former would be a
complex task, while the later is less of an issue as battery recycling becomes
more commonplace.

 

[RVD]

You guys also might be interested in a paper written by Wharton Professor Karl Ullrich on biking vs. driving. He doesn't talk about electric bikes but does write a lot about the environmental impact of human based cycling having an environmental impact that isn't as great as most people think.

This is primarily due to the following:
1) Bicyclists eat more food to fuel themselves and it takes a lot of resources to make this additional food
2) Bicyclists live longer so they do many more years of harm to the environment just by living (eating, watching tv, etc.)

Anyway, I didn't know Professor Ullrich personally (I went to Wharton as well) but knew many of his colleagues and he has a great reputation.

http://opim.wharton.upenn.edu/~ulrich/documents/ulrich-cycling-enviro-jul06.pdf

 

[neptronix]

I wrote something like this, but it is more based on the costs alone.http://neptronix.org/posts/transportation_cost.html
However we must also consider that the human body is much like an internal combustion engine, it's about 20% efficient.
And also modern agriculture uses a lot of oil, pesticides and has a lot of bad effects elsewhere like fertilizer runoff creating dead zones in the ocean, etc.

So it is not 100% carbon / pollution free to eat and use human power for a bike.
Unless you are an organic farmer and do everything by hand yourself. Only then do you have the moral upper hand

 

[stanz]

What a load of carp!

Assume this, ignore that, you can make a case for anything with that kind of "logic".

 

[julesa]

You guys also might be interested in a paper written by Wharton Professor Karl Ullrich on biking vs. driving. He doesn't talk about electric bikes but does write a lot about the environmental impact of human based cycling having an environmental impact that isn't as great as most people think.

This is primarily due to the following:
1) Bicyclists eat more food to fuel themselves and it takes a lot of resources to make this additional food
2) Bicyclists live longer so they do many more years of harm to the environment just by living (eating, watching tv, etc.)

Anyway, I didn't know Professor Ullrich personally (I went to Wharton as well) but knew many of his colleagues and he has a great reputation.

http://opim.wharton.upenn.edu/~ulrich/documents/ulrich-cycling-enviro-jul06.pdf

LOL assuming there is no way to produce food without negative environmental impact, which has nothing to do with whether the consumer is a bike rider. Growing food sustainably can have a *positive* environmental impact, though it's more expensive than most modern ag methods. Historically, humans used to be 100% clean solar powered machines, and at some point in the relatively near future we'll probably get there again.

Here's a pic of Dr. Ullrich:

 

[Doctorbass]

Well.. You know Justin Elmore?

I know him..... many E-S member have meet him. He is one of the real pioneer of electric bike technologie. This is him who developped the cycle analyst 95% of the diy ebikist now use! He also is really transparent about oppinions.

He have strong reputation and the work he did... eventhough it is from 2011 or back to 2004, i preffer believing him.

Sorry.. what he do is NOT crap! or "carp"... call that whatever you want...

He is really not the man who share bullshit.

But... Everyone can have his own oppinion ....

Doc

 

[stanz]

i preffer believing him.

Sorry.. what he do is NOT crap! or "carp"... call that whatever you want...

Doc

1) I assume that a human is riding the eBike.

2) A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

3) Therefore the energy required to grow the food is removed.

4) Human powered bike is more efficient!

 

[AussieJester]

What a load of carp!

Assume this, ignore that, you can make a case for anything with that kind of "logic".

Too true... Just dont try and argue against it with this crowd.

This is him who developped the cycle analyst 95% of the diy ebikist now use!

What a load of bullshit Dr Bass...A fine product yes and i have utmost respect for Jason,
but 95% of DIYers usinga CA?! What drugs are you one?! t..Links to support this claim please.
Theres millions of e-bikers in China alone if they all used a CA Justin would be retired by now :-S

KiM

 

[Uncle Ron]

Well.. You know Justin Elmore?

Doc,

I came back to this thread just to thank you for posting the paper, and I find that it is THAT Justin, along with various nay sayers. The nay sayers have points, yes, but I found it interesting, even if not ultimately accurate.

Since it was THAT Justin, the nay sayers might think about this. Justin went 3000 miles across Canada pushing a heavy cargo bike loaded to the gills, helping by pedaling, but doing it on less than $10 worth of electricity. Assume for a minute that Justin was a superhuman manual only biker who could push that bike only on his own at the same rate. I suspect that he'd use that $10 up in one day's extra food. Not scientific at all and it is apples to chestnuts, but it sure makes the point, I think!

 

[neptronix]

2) A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

3) Therefore the energy required to grow the food is removed.

4) Human powered bike is more efficient!

It takes calories for a human to do physical work ( pedal a bike etc )
You need about 1500-2500 calories just to 'idle'
Anyone above that is beyond what you use to do physical work.

After 20-30 miles of regular and slightly hilly pedaled bike riding, i am starved and require about 1 extra meal worth of calories over the next day or two.

People lose weight by excersizing ( using excess calories, or removing ones that have been stored as fat )
If physical work didn't burn calories above what we normally use, nobody would ever lose weight.

Ask a bodybuilder, athlete, olympic medalist if they eat more when they are training or competing.

I think you are missing a pretty fundamental fact of thermodynamics here.

 

[Doctorbass]

What a load of carp!

Assume this, ignore that, you can make a case for anything with that kind of "logic".

Too true... Just dont try and argue against it with this crowd.

This is him who developped the cycle analyst 95% of the diy ebikist now use!

What a load of bullshit Dr Bass...A fine product yes and i have utmost respect for Jason,
but 95% of DIYers usinga CA?! What drugs are you one?! t..Links to support this claim please.
Theres millions of e-bikers in China alone if they all used a CA Justin would be retired by now :-S

KiM

Kim... Probably this is not really 95%.. I might have exagerated..... sorry.. it might was the solder iron fumes of past 2 hours... ( drugs )

But nearly every time i see an ebike from DIYer on youtube, in my city, in pictures... etc I see they HAVE a C-A...


But this is not the point... What i want to say is that Justin never said any bullshit. you dont agree?... give me a single exemple!

By the way.. just by existing a human consum the equivalent of 100Watts.

 

[Doctorbass]

2) A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

3) Therefore the energy required to grow the food is removed.

So you know the solution for FREE ENERGY !!! let's put alot of Humans on ebikes in Regen mode all connected to a big converter and to the grid and ask them to pedal...

according to your opinion.. that mean we will create FREE ENERGY !!! .....



Cmon !!

4) Human powered bike is more efficient!

so you say Justin is writing stupidity in his report?

What Justin meant is that the food to give you the energy to travel in ebike require fabrication, transport, storage, freezer, oven, etc...

by calculating everything that is required to produce that food, the energy that each joules that give that food require ALOT more than what it give in ennergy to a human

Adding the problem of the efficiency of a human to convert the entire energy of the food to mecanical energy, make the result worst.

did you REALLY read that document?

Doc

 

[Kurt]

I would have to agree with Doc on this one.

We are simply talking about total energy consumption to achieve mechanical work. We modern day humans that fuel our bodies at the local supermarkets would be more wasteful. If you really had to account for every bit of energy consumed to get that food to your body, you would be shocked.

There is probably a peak amount of mechanical work a human's body can do. Once you reached peak physical condition, there would be a daily limit to the level of mechanical work your body could do and sustain over a lifetime before it would start being detrimental to your health. I would say that a lot of overweight people could work from their reserve for a little while. But in the end, you can only get out what you put in and there is no argument there.

Do extra at work, you need to eat more.

Kurt.

 

[stanz]

What a great topic, maybe we should add global warming to it to really generate heated discussion.

What Justin meant is that the food to give you the energy to travel in ebike require fabrication, transport, storage, freezer, oven, etc...

by calculating everything that is required to produce that food, the energy that each joules that give that food require ALOT more than what it give in ennergy to a human
Doc

Now you understand my problem with the paper! If you calculate the minutia of the human side of the equation but toss out factors of the eBike side as insignificant it is bad science.

One example of this is the weight, the document states "the additional weight of the motor and battery pack is small compared to the gross vehicle weight". My bike is a Specialized Endurance Sport with a stock weight of 33.77 pounds. My direct drive hub motor from AmpedBikes weighs 14 pounds alone. By the time you add the controller, batteries and controls the additional weight could not possibly be considered "small".

Another example is rolling resistance. According to AmpedBikes the direct drive motor's rolling resistance is "equal to about a 4-5 mph headwind".

If I had presented a term paper like this in high school it would have been ok, but if I presented it at RPI I would have been ripped apart for incomplete science. You can't pick and choose which parts of a scientific equation to include and draw a conclusion. You must include ALL the parts to be accurate.

Oh, and yes, I read the document a couple of times trying to justify the conclusions.

 

[stanz]

It takes calories for a human to do physical work ( pedal a bike etc )

...

After 20-30 miles of regular and slightly hilly pedaled bike riding, i am starved and require about 1 extra meal worth of calories over the next day or two.

...

Ask a bodybuilder, athlete, olympic medalist if they eat more when they are training or competing.

I think you are missing a pretty fundamental fact of thermodynamics here.

I guess I should have explained my POV on bike riding in my town. I live in a small town where hundreds of individual bike trips occur everyday, the vast majority is done by grade school children going to and from school. We have 3 grammar schools, 2 middle schools, and one high school. The number of bikes at the grammar schools are greater than the totals at the middle schools which are far greater than the number at the high school. This has to do with the topography of our town I suspect. Most grammar school kids can make the less than 1/2 mile trip to their school on nearly level ground. Fewer kids can do the same at the middle schools and there are fewer bikes because of this. It's hard to make the trip to the high school without encountering a hill.

Using the real world bike travel in my town of short mostly level trips would consume few calories compared to a 20 mile trip. The kids might need a drink but not a meal.

I DO understand thermo, my point was to use similar logic to the term paper to make a point. One assumption can weigh heavily in the final calculation and should not be ignored.

 

[Xrain]

What a great topic, maybe we should add global warming to it to really generate heated discussion.

What Justin meant is that the food to give you the energy to travel in ebike require fabrication, transport, storage, freezer, oven, etc...

by calculating everything that is required to produce that food, the energy that each joules that give that food require ALOT more than what it give in ennergy to a human
Doc

Now you understand my problem with the paper! If you calculate the minutia of the human side of the equation but toss out factors of the eBike side as insignificant it is bad science.

One example of this is the weight, the document states "the additional weight of the motor and battery pack is small compared to the gross vehicle weight". My bike is a Specialized Endurance Sport with a stock weight of 33.77 pounds. My direct drive hub motor from AmpedBikes weighs 14 pounds alone. By the time you add the controller, batteries and controls the additional weight could not possibly be considered "small".

Another example is rolling resistance. According to AmpedBikes the direct drive motor's rolling resistance is "equal to about a 4-5 mph headwind".

If I had presented a term paper like this in high school it would have been ok, but if I presented it at RPI I would have been ripped apart for incomplete science. You can't pick and choose which parts of a scientific equation to include and draw a conclusion. You must include ALL the parts to be accurate.

If you add a 180 pound human in the equation it's 213.77 stock, and ill say 255 for the bike an 19% difference in weight in this case isn't all that significant.

As adding extra weight to a rolling vehicle doesn't have a large effect on the efficiency. As it only increases the amount of energy required to accelerate not the steady state consumption, as well as a slight increase in resistance in the tires.
If the conversion to electric significantly increases the aerodynamic cross section then yes, that will have a very large effect on energy consumption.


His paper makes logical assumptions, throwing out items that would be computationaly intensive, without a overly significant effect on the final result.

Rolling resistance is an effect of an unpowered motor, creating a magnetic flux in the coils resisting forward movement. The effect for all intents and purposes disappears when you add power to the motor. So the only resistance provided by the motor is the losses in the bearings and eddy current losses. which work out to around 95% efficient on a BLDC motor, with greater losses in the controller as it converts the DC to an AC output.


If he made these assumptions and then didn't detail them then yes, this would be a very poor paper. But there is nothing wrong with slightly idealizing a situation like this as its not an in-depth study into the economics of ebikes, as I seriously doubt just one person could adequately investigate factors involved.

So for a brief introduction on ebike economics it is an adequate source, but it also must be noted the paper does use an idealized world, and will not necessarily reflect exactly what the real world would be like, but it would definitely be within the ball park.

 

[stanz]

If you add a 180 pound human in the equation it's 213.77 stock, and ill say 255 for the bike an 19% difference in weight in this case isn't all that significant.

Now you are adding detail to the term paper. I refer to the content of the paper which refers to the "gross vehicle weight", not the weight of the vehicle and a 180 pound or 120 pound rider. The weight of the rider is a constant, an undocumented constant.

There are other areas of the paper that are problematic as well. For instance, the paper assumes the charging cycle of the battery is exact or nearly so. How many ebike owners unplug their charger exactly when the battery is done charging? I suggest that the charger will remain plugged in for X hours consuming more electricity. (Not as much as when it is charging of course.) Again, this is adding data missing from the paper.

I TOTALLY agree that an ebike is a very efficient mode of transportation, my problem is with the logic used to discard parts of the equation.

If I were writing a paper on ebikes I would go further and include solar electric charging of the battery pack. To me this is the ideal argument for ebikes since it eventually lowers the carbon footprint of the ebike to nearly zero. (If you disregard the carbon impact of the rider since the rider would need some form of transportation anyway.)

 

[julesa]

I DO understand thermo, my point was to use similar logic to the term paper to make a point. One assumption can weigh heavily in the final calculation and should not be ignored.

So, then you acknowledge the post quoted below is completely wrong?

1) I assume that a human is riding the eBike.

2) A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

3) Therefore the energy required to grow the food is removed.

4) Human powered bike is more efficient!

The energy dissipated by aerodynamic drag is larger than all other factors put together.

If I had presented a term paper like this in high school it would have been ok, but if I presented it at RPI I would have been ripped apart for incomplete science. You can't pick and choose which parts of a scientific equation to include and draw a conclusion. You must include ALL the parts to be accurate.

LOL. Every paper makes assumptions. Equations representing real world phenomena are ALWAYS approximations.

 

[Xrain]

If you add a 180 pound human in the equation it's 213.77 stock, and ill say 255 for the bike an 19% difference in weight in this case isn't all that significant.

Now you are adding detail to the term paper. I refer to the content of the paper which refers to the "gross vehicle weight", not the weight of the vehicle and a 180 pound or 120 pound rider. The weight of the rider is a constant, an undocumented constant.

There are other areas of the paper that are problematic as well. For instance, the paper assumes the charging cycle of the battery is exact or nearly so. How many ebike owners unplug their charger exactly when the battery is done charging? I suggest that the charger will remain plugged in for X hours consuming more electricity. (Not as much as when it is charging of course.) Again, this is adding data missing from the paper.

I TOTALLY agree that an ebike is a very efficient mode of transportation, my problem is with the logic used to discard parts of the equation.

If I were writing a paper on ebikes I would go further and include solar electric charging of the battery pack. To me this is the ideal argument for ebikes since it eventually lowers the carbon footprint of the ebike to nearly zero. (If you disregard the carbon impact of the rider since the rider would need some form of transportation anyway.)

Did you read the paper in it's entirety? He made a second comparison of Vancouver which gets a majority of its power from hydro-electric power. While its ecologically damaging, it has zero-carbon foot print.

Any decent quality charger will be micro-controller controlled, and would only draw a few tens of mA if that. even if you left it on for several hours, its not really statistically significant enough in a paper like this to be worth considering.


Let me make an example. When you perform a circuit analysis. You make plenty of assumptions, such as your wires have no resistance, certain components well behave linearly, your circuit is at standard pressure and temperature.

And these assumptions work just fine. All those factors add up to something statistically insignificant, and in standard cases using these idealized assumptions works just fine.

However, it is certainty possible to find times where these assumptions break down, such as if your circuit is going to work in an extreme of temperature, or there are high frequency components on it. Then you have to factor in the resistance of the traces, and non linear component reactions, since it has become statistically significant.

The same holds true for an analysis like this. If the title of the paper was "Economic Comparison of ebikes and bicycles in really hilly places with lots of stop lights" Then yes, assuming steady state speeds would be a poor practice.

Now you are adding detail to the term paper. I refer to the content of the paper which refers to the "gross vehicle weight", not the weight of the vehicle and a 180 pound or 120 pound rider. The weight of the rider is a constant, an undocumented constant.

A gross vehicle weight rating (GVWR)[1] is the maximum allowable total weight of a road vehicle or trailer when loaded - i.e including the weight of the vehicle itself plus fuel, passengers, cargo, and trailer tongue weight.

If he was to write a paper to the detail you seem to be requiring, it would be several hundred pages long, possibly a few thousand, you would have to recursively re-analyze any sources of information for estimated carbon foot print of food, batteries, air-planes, as they would no longer be sufficiently in depth enough to be a reliable source of information.

It would be a massive undertaking for not a very significant change the the relationship.

This is the kind of analysis that teams of hundreds of people spend millions of dollars doing. This is more on the scope of a Governmental inquiry. Not a Sophomore level University Term paper.

 

[stanz]

I DO understand thermo, my point was to use similar logic to the term paper to make a point. One assumption can weigh heavily in the final calculation and should not be ignored.

So, then you acknowledge the post quoted below is completely wrong?

1) I assume that a human is riding the eBike.

2) A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

3) Therefore the energy required to grow the food is removed.

4) Human powered bike is more efficient!

The energy dissipated by aerodynamic drag is larger than all other factors put together.

Of course my post is wrong, that's the point! I made an assumption, an exaggerated one, to make a point about the assumptions in the term paper.

 

[julesa]

Of course my post is wrong, that's the point! I made an assumption, an exaggerated one, to make a point about the assumptions in the term paper.

That point has also been demolished. So are you going to take back calling it "a load of carp," then too? 'Cause seriously, I'm concerned Justin might be heartbroken that someone is going around comparing his paper with pond fish.

 

[REdiculous]

A human will consume roughly the same amount of food everyday if they ride or don't ride. I know I do.

Part of being healthy is getting daily exercise so you should be able to do 10 miles without eating more if you aren't trying to win a race. The only time I ever ate significantly more was when I'd do 40-80 miles in a day. :|

 

[SamTexas]

If I had presented a term paper like this in high school it would have been ok, but if I presented it at RPI I would have been ripped apart for incomplete science.

And to use 1,000 cycles for battery in the cost calculation in 2006 is beyond optimism. Even worse is the claim that the motor/hub, controller and charger would last forever.

This is not a term paper. This is a sale brochure.

 

[julesa]

Part of being healthy is getting daily exercise

Which nobody ever fails to do, right? I mean, a person who chooses to drive instead of biking on a particular day will always make up the exercise later that day. Right? Um... not necessarily. Some people will get more exercise than is strictly necessary for health, and then on the same day they will also choose to bike to work over driving, in spite of the fact that it won't make a significant additional improvement in their health. But it will still burn the same amount of energy. Rider health is an orthogonal factor.

The only time I ever ate significantly more was when I'd do 40-80 miles in a day. :|

What exactly do you mean by "significantly"? Justin provided numbers in his paper, do you have better ones?

It's a fine term paper, and deserves way better than to be compared to goldfish.

And to use 1,000 cycles for battery in the cost calculation in 2006 is beyond optimism. Even worse is the claim that the motor/hub, controller and charger would last forever.

It would be beyond optimism if he was talking about SLA batteries with that number, which he wasn't. It's probably a low figure for NiCads or modern Lithium chemistries. All of which is accounted for in the paper. All his battery life cycle estimates are more conservative than most battery manufacurer's published specifications. And he didn't say those other components had an infinite life span, he said they have an indefinite life span. Minus five points for reading comprehension, Sam.

Come on, people. It's a college term paper. Life cycle analysis for every component on the level of aerospace engineering is a little bit out of the question. Get real.