Human power

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gadfly56 said:
Obama and Co. have put the kibosh on funding in 3rd world countries for cheap coal-fired power plants. If you want a prime example of colonial-style repression, you couldn't find better.
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Even if that's true (and I don't know that it is), and pushing environmental concerns aside, how is not giving away money tantamount to repression? Bill Gates must be repressing me big time. :D
 
ggunn said:
Even if that's true (and I don't know that it is), and pushing environmental concerns aside, how is not giving away money tantamount to repression? Bill Gates must be repressing me big time. :D
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I was somewhat imprecise. The drive is to veto any LOANS to construct fossil-fueled power plants. World Bank, IMF, American Aid, whatever. This is not about giving away money or not giving away money. Once folks can kick-start local or regional economies via the presence of reliable electrical power, all kinds of good (economic) things start heading their way. With a growing economy, they can pay back their loan as the debt becomes a smaller and smaller proportion of the economic picture.
 
gadfly56 said:
I was somewhat imprecise. The drive is to veto any LOANS to construct fossil-fueled power plants. World Bank, IMF, American Aid, whatever. This is not about giving away money or not giving away money. Once folks can kick-start local or regional economies via the presence of reliable electrical power, all kinds of good (economic) things start heading their way. With a growing economy, they can pay back their loan as the debt becomes a smaller and smaller proportion of the economic picture.
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Nevertheless, the lack of granting a loan to a country is not, IMO, oppression.
 
Early power

Early power

150107-2348

Three photos of very early steam power. A good excerise is to calculate the steam pressure required. What kind of piston seal might have been used? How much coal per hour at 20 HP output? Possible efficiency?

PICT2996.jpgPICT2997.jpgPICT3001.jpg
 
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Back to human power.

The first design that comes to mind is a human pedaling a stationary 'bike' to turn an alternator.

Here are some details that need some attention.

A human can pedal about 100 rpm for a decent period of time.

An alternator starts charging at around 1000 rpm and peaks closer to 3000 rpm.

We have pretty much summed up that the human engine is good for 50-100 watts or so for any length of time. 500 watt short bursts are available. So, we are looking at less than 10 amps at 12 volts for any length of time and a peak of 40 amps or so.

So we either need some decent (1:20) gearing, or we need an alternator that can produce 10 amps at a much lower rpm.

I'm not up on alternator technology, but I'll bet there is a way to modify them to produce less current but do it at a lower rpm.

Any ideas?
 
150208-0936 EST

dfmischler:

Thanks for the article. Very useful. There had to be a great deal of thought and experimentation to arrive at the first real working machine. This also brings up the question of how these large components were made (cast and machined), and adequate precision obtained.


K8MHZ:

You make the diameter large.

See the large generator of the Ford Highland Park Model T factory. Four megawatts at 250 V, 6000 HP steam and gas engine (stroke 72", compound steam high pressure 36" dia, and low pressure 72" dia; gas (coal gas) 42" dia).

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150208-1157 EST

K8MHZ:

I failed to include the critical factor --- 80 RPM direct drive. With a large diameter rotor the linear velocity at the magnetic cutting field point can be high, and thus, e = N * df/dt is high. I will guess 8 to 10 feet for the radius of the Highland Park generator. Compare this to 2 to 4 inches in a car alternator. Possibly a 50 to 1 ratio.

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Are there any health clubs where all their machines' resistance is done with generators and their output summed and interconnected with the grid?
 
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