Analysis of electric bike usage in China
- Thread starter Miles
- Start date
Miles,
A fascinating article. Thanks for posting it.
The single most interesting fact for me was the comparison of the operating costs of 3ebikes and other forms of transport, which show them being the cheapest, even compared to a normal bicycle. The note at the end gives the explanation:
Ulrich, K “The Environmental Paradox Of Bicycling” Working paper, Dept of Operations and Information
Management, Wharton School, July 2006, p.3. Surprisingly, a bicycle has lower efficiency than an e-bike because
the body is only 22% efficient in turning food energy into work.
Frank
A fascinating article. Thanks for posting it.
The single most interesting fact for me was the comparison of the operating costs of 3ebikes and other forms of transport, which show them being the cheapest, even compared to a normal bicycle. The note at the end gives the explanation:
Ulrich, K “The Environmental Paradox Of Bicycling” Working paper, Dept of Operations and Information
Management, Wharton School, July 2006, p.3. Surprisingly, a bicycle has lower efficiency than an e-bike because
the body is only 22% efficient in turning food energy into work.
Frank
It may be true that the best efficiency you can get out of a human being is around 20-25% (the rest of the energy being used in maintaining metabolic processes, i.e. keeping us alive), though this is still somewhat better than the 15-20% efficiency of electricity generation and losses through the national grid.
In other words, the 100% of latent energy in a lump of coal or uranium is severely reduced by converson and delivery processes, in getting electricity to one's wall socket. Therefore whilst an ebike motor might be relatively efficient per se, getting the 'fuel' to charge it, is most certainly not. There are huge inefficiences to accounted for before the ebike has even been charged up and ridden. And that's before you start taking into account all the crud coming out of the power station chimneys and the energy required delivering the coal to the station etc etc.
I'd say that efficiency of an ebike should be measured in terms of embodied energy rather than delivered energy to get a truer comparative picture, and I suspect it would be rather lower than a conventional bike.
In other words, the 100% of latent energy in a lump of coal or uranium is severely reduced by converson and delivery processes, in getting electricity to one's wall socket. Therefore whilst an ebike motor might be relatively efficient per se, getting the 'fuel' to charge it, is most certainly not. There are huge inefficiences to accounted for before the ebike has even been charged up and ridden. And that's before you start taking into account all the crud coming out of the power station chimneys and the energy required delivering the coal to the station etc etc.
I'd say that efficiency of an ebike should be measured in terms of embodied energy rather than delivered energy to get a truer comparative picture, and I suspect it would be rather lower than a conventional bike.
It gets complicated - you'd also have to analyse/quantify the energy used to grow and transport the food used for a specific persons energy source and the energy used to produce the two products and their replacement parts, throughout their lifecycle.....
Here's one attempt at a comparison: http://www.ebikes.ca/sustainability/Ebike_Energy.pdf
Here's one attempt at a comparison: http://www.ebikes.ca/sustainability/Ebike_Energy.pdf
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Absolutely right Miles. Comparing relative efficiencies in transport systems is tricky and depends on where the boundaries of comparison are set. Does one just consider the bike itself, and/or it's fuelling services, and/or it's manufacture etc etc.
Fascinating stuff though, and with a lot of published papers one also has to watch out for 'vested interests' too. Systems analyses for food production is even worse! Conventional vs. Organic vs GMOs... I have some sympathy for those trying to make policy decisions.
Fascinating stuff though, and with a lot of published papers one also has to watch out for 'vested interests' too. Systems analyses for food production is even worse! Conventional vs. Organic vs GMOs... I have some sympathy for those trying to make policy decisions.
I thought the circa 25% figure was for the efficiency of the conversion to mechanical output, only (that's why you sweat a lot!)? After all "staying alive" is a given, in the equation, hopefully....
There is an excellent book "Prime Mover - A Natural History of Muscle" by Steven Vogel (all his books are fantastic) this area is also covered in "Bicycling Science" 3rd Ed. D.G. Wilson
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Sorry Miles, that's just my poor writing. I took the statement "the body is only 22% efficient in turning food energy into work" to mean that out of the 100% of food energy available when ingested, only ~22% can be converted into 'mechanical' work (in this case turning the legs). In other words the human body uses up the remaining ~78% keeping us alive.
Not all of that that 22% of energy output as work by the cyclist will be converted into motion by the bicycle of course, as it will have its own inherent inefficiences, so that will contribute to raising a sweat. Oh, and going up hills of course!
Not all of that that 22% of energy output as work by the cyclist will be converted into motion by the bicycle of course, as it will have its own inherent inefficiences, so that will contribute to raising a sweat. Oh, and going up hills of course!
For me the gloomy aspect of the report is the combination of Chinese taste in e-bikes and the size of their home sales.
Given the tiny sales in export markets in comparison, there's little chance of an importing country like ourselves influencing design in the direction of our national preferences and needs.
In general only the smaller and often Taiwan based companies sometimes listen, and their product tends to be much more expensive than the mainstream Chinese production.
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Given the tiny sales in export markets in comparison, there's little chance of an importing country like ourselves influencing design in the direction of our national preferences and needs.
In general only the smaller and often Taiwan based companies sometimes listen, and their product tends to be much more expensive than the mainstream Chinese production.
.
I hadn't clocked that Flecc, 10 million units in 2005! Be a while before we shift that number here, if ever. I guess it's wishful thinking against those kind of numbers of having any kind of influence at all.
Another study, by the same team, this one on environmental impact:
http://www.its.berkeley.edu/publications/UCB/2007/VWP/UCB-ITS-VWP-2007-2.pdf
http://www.its.berkeley.edu/publications/UCB/2007/VWP/UCB-ITS-VWP-2007-2.pdf
Same as if you grow all your food, organically, in your back garden, I guess..
..I guess to do a full cost evaluation you'd have to add up the total energy used to manufacture the parts used to make & run the renewable energy production source e.g. wind turbines, solar panels etc. aswell as energy costs of bike production, then weigh that up against the total energy produced by the renewable source & used by the bikes over the working lifetime of both... that would give you the full picture of energy outlay vs renewable energy "returns"...John said:
That again is very complicated, as for the food production side Miles mentioned earlier, but I think the cost of ebikes in terms of energy & pollution is most likely lower than most, if not all, manufactured forms of motorised transport, and though conventional bikes or even horses etc. may be more energy efficient or even preferable in a better world, I don't see them presently as practical solutions to transport, especially urban.
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You don't see bikes as practical solutions to urban transport Stuart!!!!!!!!!!
Revolutions have been started for less.
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Sorry, I meant conventional bikes (as opposed to electric/motorised bikes) are less suited to "middle distance" transport, like 20-30mile+ trips, especially in hillier areas, with today's more "motorised" lifestyle: maybe I'd feel differently if I were even remotely as cycle fit as Tour de France leaders! If thats still rebellion material, well, it all helps the cause of cycling! Best publicity & all that...
.Stuart.
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Just don't say it to A to B!
Man, Woman and Child, they go to shows all over the country by train and unpowered bike and don't own a car.
For the New Milton show they caught a train to another town station quite a distance away and cycled the rest on their Bromptons, little Alexander putting many an adult cyclist to shame with his cycling prowess and speed.
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Man, Woman and Child, they go to shows all over the country by train and unpowered bike and don't own a car.
For the New Milton show they caught a train to another town station quite a distance away and cycled the rest on their Bromptons, little Alexander putting many an adult cyclist to shame with his cycling prowess and speed.
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I'd be happy to be as fit as the stragglers.maybe I'd feel differently if I were even remotely as cycle fit as Tour de France leaders!
Ian said:
Very true, me too! & even that's beyond me! I was looking that far up the "field" so that when I fall way short of the stragglers I can at least be pleased with some progress!....flecc said:
OK, good for them that they do that! I'm only one step away from that: train, ebike & no car, the latter as much due to "making do" without one as unwillingness to drive one. I do go by car when journeying with someone who's driving anyway, but to be honest I dislike car travel immensely to the extent I only use it as a necessity, and even then it doesn't seem absolutely so!Sorry to drift OT Miles... but...
Cycling from a young age is, I think, extremely good for our society, which is becoming progressively sedentary and suffering for it, and I'm certainly not seeking to encourage lack of exercise; its just I feel the in the busy modern environment its becoming increasingly difficult to easily find spaces in which to do it in a safe, relaxed & enjoyable way - especially for children: a generation is growing up, many of whom have never experienced playing/exercising outdoors on a daily basis...
I'm discovering more & more the potential of the Torq for transport, exercise & fun though (not a T-bike, but still immense fun!
) as I rediscover my cycle legs, it really does feel like "augmented" biking, and the best bit is that by using it in that way i.e. very "active/energetic" cycling combined with the motor speed, I think one can get both better speed & range with careful throttle use, since every Watt of legpower used saves around 1.25W of battery power , so 50W more continuous legpower for 1 hour saves around 62.5Wh of battery power, or up to around 5 or 6 miles extra range per charge . I should add that my terrain is not very hilly, on well-chosen routes just the odd gradient up to around, say, 5-7% tops, for convenience.And of course, the "power assisted" experience would be much smoother & more efficient with 2 or 3 hub motor gears
.Stuart.
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Yes, the motor gearing is important Stuart, even with single gear. The Q bike gives a considerably greater range than the T bike on the same motor, same rider, same territory, but the T bike's overgeared motor wrecks it's results.
It has to work too hard and I'm not able to work in synch with it as effectively as I can with the moderately geared motor of the Q bike.
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It has to work too hard and I'm not able to work in synch with it as effectively as I can with the moderately geared motor of the Q bike.
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