Turbo Trainer = Generator?

dynamicbrick

An hour on the trainer this evening, medium pace with intermittent sprint/high tempo stuff.

Between one of the sprints, my mind was wandering and starting considering the resistance of the trainer, which led illogically to generating electricity.

Despite my late father being an electrician, and me spending my entire life mucking about with mechanical things as a hobby and mainframes and datacentres as a day job, I haven't got the first idea how much force is required to drive something like an alternator.

The only reference point I have is a small/domestic Genny which puts out 3HP (IIRC) and will happily run the essentials in the house. But whether a human on a bicycle is capable of generating similar torque and rpm (HP being a result of lb-ft and rpm) is beyond my skill to work out.

Would it be theoretically possible, or would there be too much resistance and silly gearing required to spin something fast enough?

chrisaonabike

One horsepower is about 750 watts, I think, so good luck powering your house there

gavbarron

You couldn't power your house directly but you could rig it up to charge a battery without too much work or spare parts, that battery could power a light and computer in the garage for your turbo. This topic has been brought up a few times and general consensus is that it's not worth the effort

jim453

Few things actually are.

dw300

Lol .. I know you know HP standing for Horse Power, so I'm wondering how you think a human could possibly generate that amount .. ?

Anyway .. lets say you can produce 250W for an hour .. it'd take 4 hours to produce 15 pence worth of electricity. Although you should put out heat at a comparable rate to a 750W heater.

Anonymous

Didn't you watch the matrix? They were in giant condoms , not in turbo trainers.

gavbarron

Human power output, taken from Wikipedia (which I appreciate is not always an accurate source):

"When considering human-powered equipment, a healthy human can produce about 1.2 hp briefly (see orders of magnitude) and sustain about 0.1 hp indefinitely; trained athletes can manage up to about 2.5 hp briefly[11] [12] and 0.3 hp for a period of several hours"

t.m.h.n.e.t

Or you could buy a turbo that has powerback?

buckmulligan

Haha, it does put into perspective just how much energy you consume in your home. And just how inefficient cars are!

chrisaonabike

dw300 wrote:

Anyway .. lets say you can produce 250W for an hour .. it'd take 4 hours to produce 15 pence worth of electricity. Although you should put out heat at a comparable rate to a 750W heater.

Eh?

GiantMike

ChrisAOnABike wrote:

dw300 wrote:

Anyway .. lets say you can produce 250W for an hour .. it'd take 4 hours to produce 15 pence worth of electricity. Although you should put out heat at a comparable rate to a 750W heater.

Eh?

Your body uses approx 4 calories for every calorie of effort it produces (i.e. 25% efficiency). The other 3 do not produce power but are still being used. Some of this 'other energy' produces as heat (though probably not 750W).

ETA: If you had a decent heat exchanger you could convert some of this heat to power.