We've told you about bike-sharing programs before, but the Hybrid2 design by Chiyu Chen takes the idea one step further, by using the bikes to put power back in the system. The idea is to put "ultracapacitors" into the bikes that will harness and store the kinetic energy generated by pedaling and braking. Once you return the bike to its rental kiosk, the energy stored in the bike will be transferred to the city's smart grid, and used to help power hybrid buses.
The city doesn't simply expect you to generate free electricity for them. The bikes come equipped with handlebars that display how much energy has been generated over the course of your bike ride. Once you return the bike, depending on how much you are putting back into the grid, you get a voucher towards your next bus ride. The bike stands themselves will be solar powered, with RFID chip readers, so you could have an ID card that stores bus credits over successive bike rides.
We here at PopSci were a bit skeptical about just how much energy could be generated by one bike, so we did the math. Theoretically, let's take a 10-kilogram bike that has an average speed of 10 meters per second. Using some basic physics, it turns out the amount of kinetic energy generated in one second would be 500 joules. Not bad. However, that is assuming that the capacitors in the bike are 100 percent efficient and capture every bit of energy (which isn't possible), and that no energy is lost due to heat and other factors. If all the energy was captured, it would be the equivalent of 1/100th of a gram of combusted gasoline in a normal bus. If you had a legion of these bikes generating power, the harnessed energy could be fairly significant.
We also are speculating that these bikes might be a bit more difficult to pedal, which could lead to a powerful thirst. Might we suggest a bottle-top bike clip to keep you hydrated?
I don't know that I have any extra energy in my bike. I have enough trouble staying going on my own.
"the amount of kinetic energy generated in one second would be 500 joules"
I'm not sure that you got your physics right. A joule when applied to power is equal to one watt second, Thus 500 joules would be 500 w/s. If If applied over an hour, it would be 500 watt hours. or a half of a kilowatt hour -- pretty good. Maybe you meant that you would get 500 joules (total) over a journey of some distance.
I've heard from bike racers ( not me! ) that a good racer can generate something like an eighth of a horsepower. How much could be stored as energy while still managing some reasonable bike speed, I don't know. And yes, you would gain some by regenerative braking -- although that would probably add weight to the bike.
I've got a better idea, just put pedals at every seat in the bus and everyone will chip in. I'm having flashes of the flintstones here.
If those bikes really use "ultracapacitors" (not sure what the quotes are indicating) those things will be a prime target for theft. Yingyangs web site has no information on it either.
Sorry, this is a totally bad idea.
Bicycling is hard enough work already, and having some device slow my bike down while I'm working hard to get somewhere on time would be extremely annoying.
Now maybe the "ultracapacitor" technology could be useful for other things, like charging it up with the pedals while stopped at a traffic light, and then using it to assist with acceleration. But this would only work if it did not weigh too much.
It would make loads more sense the other way around. Have the freaking bus charge the bikes. This would actually boost rider-ship and make the bus more efficient by virtue of splitting the fuel amongst more bus riders. If it reduced traffic congestion it would make the bus more efficient by reducing stop-and-go conditions.
Gosh, this very idea got trashed on ecomodder.com just yesterday. So, let's assume that we are going to use the mass of both the bike and rider, and recover their kinetic energy from a stop, after coasting down to 10.9 MPH. That's equal to 1/2 second of free-fall, which goes 4'. With a combined weight of 200 lbs, we get 800 ft-lbs. Someone might do that every minute, giving an average return of .024 HP. That much might be considered "spare" from an average output of .1 HP, although the temptation would be to use that same generator as a motor, to help acceleration or hill climbing. After an hour, you'd have 18 watt-hours, or about 1/5 of a cent's worth.
Calculators make math so easy, I'm amazed that nobody seems to do it any more. The "pennies per charge" boast on electric bike ads is a big clue.
We can change anything.60 times in an hour
But we can never change
just one thing.
.... Really! i mean its a wonderful idea and it would work in Europe but in the states, how many people per capita bike? excluding California, Florida, and Colorado