

Automata: engineering for a post-oil world? - rudenoise
http://www.lowtechmagazine.com/2010/11/automata-engineering-for-a-post-oil-world.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+typepad/krisdedecker/lowtechmagazineenglish+(Low-tech+Magazine)

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icegreentea
I imagine as you start scaling the size of machines/automata up, it becomes
more efficient to have your crank/windmill/whatever turn an electric generator
that then drives an electric motor. Any ideas on where this tip over point is?

You lose the artistry though.

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crpatino
I am not sure to understand what you mean by "scaling up size", would you mind
to elaborate?

On the other hand...

>> it becomes more efficient to have your crank/windmill/whatever turn an
electric generator that then drives an electric motor.

Efficiency is not an absolute property of systems, but it depends on the
variable that you are seeking to optimize. If you talk about _energy_
efficiency alone, this is a really bad idea. First you use the crank to turn
the chemical energy of the meal you just had into mechanical energy, then you
turn this into electric energy by using the generator, then the generator
powers a motor to turn that one back to mechanic energy. Every step of the
process has a conversion factor < 100%, and besides that, every step of the
chain has leeks in it. The longer and more complex the process, the less
efficient. Period.

Now, if you need a _steady_ source of mechanic energy, but you have just a
sporadic one, this begins to make sense. You connect your sporadic
crank/windmill/whatever to a generator, the generator to a battery, and feed
the motor from the battery... and you get a small steady flow out of a big but
unreliable one. But it all depends of what you are trying to optimize for in
the first place.

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icegreentea
In my (probably overly simplistic view), a generator-motor system will have
roughly constant energy efficiency as you make it larger and larger, while the
energy efficiency of a purely mechanical system will decrease, as you spend
more and more energy on moving the mechanical connections which increases in
mass by the cube, while your energy gathering surface goes up by the square.

So for example if you had some wind drive automata that plowed a field for you
(and assuming constant wind), if you were talking about a machine that worked
1m^2 per minute, a purely mechanical system would have higher energy
efficiency. But if you made the design larger so it could work 4m^2 or
something, the now you have higher energy efficiency with a generator-motor
system.

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RodgerTheGreat
The notion of wind-powered automata plowing fields immediately brought Theo
Jansen's Strandbeest machines to mind- very evocative. Oh, now I need to find
some watercolors... or perhaps some plastic tubing.

