Energy From Giant Hand-Cranks in a Post-Apoc World?

AlyssaCroft

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I know virtually nothing about how energy works, but hopefully I know enough to bluff through this. Please let me know if I'm on the right track or not!

I'm trying to think how people can create electricity in a post-apocalyptic world. Not a huge amount of electricity mind you, just enough for basics like minimal lighting and maybe some fans to help circulate air.

Presume that there is no access to coal, gas, or oil. The means of creating and storing power has to be something that can be created by some clever handymen using found materials- anything that requires large amounts of electricity to create is off-limits. They're creating energy from fire, water, wind and/or human power.

I start thinking about those little hand-crank devices people use in their bug-out bags. The little hand-crank radios and spotlights. Person consumes energy by eating, then use that energy to crank the handle, which transfers the energy to the device (through magnets, yes?).
What happens if I make a GIANT crank device, perhaps people using some sort of see-saw motion (thinking of those hand-crank train carts here), that simultaneously spins a large collection of magnets, which then feeds energy into... what? I'm not sure if I want to use a battery, as those have a lifespan, which is likely virtually over by the time this device is created. Perhaps the energy is fed through regulators and distributed directly to the equipment that requires the energy (e.g. light bulbs)?

My story is set in a somewhat Miyazaki-style world (only decidedly darker), so the world isn't strictly based on science. But I do want to show enough where people can believe it might be possible.

Any suggestions or extra info would be hugely appreciated!
 
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alleycat

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In medieval times they used a device to hoist stones and other building materials that was a large, circular wooden thing similar to a hamster cage. One or two men would "walk" inside the device to supply the power. I suppose something similar could be used to generate electricity in your story world assuming the people know how to build a magneto.
 

waylander

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Anything wrong with a watermill driving a dynamo?
There could still be surface deposits of coal accessible from open-cast mines.
 

Trebor1415

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In WWII there were hand crank transmitters. They later figured out it was better to set them as bicycle type cranks instead of hand cranks. You'd go more for the effort that way.

The amount of energy generated that way is severely limited though. We're talking enough to power a transmitter for only as long as the person was cranking or pedaling. You could also use it to recharge batteries, but it took a LONG time.

Personally, person generated electricity in a story would be a red flag that the writer doesn't really know what he's talking about in that area, unless it was limited to a specific duration use. (Cranking a broadcaster, or a receiver, or emergency lighting or some such).

Just using it as a "regular" way to generate electricity for normal uses, such as lighting or AC, would be a bit much, in my opinion. It's just not that efficient.
 

Torgo

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"The Windup Girl" by Paolo Bacigalupi goes into this in depth - 'what if we had to get all our electricity from cranking stuff' is the basic premise of the book. A short story in the same world is here.
 

benbenberi

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Human-powered hand cranks are a very limited and inefficient way to generate energy. Even if you restrict yourself to human-powered methods there are better ways to do it - large treadmills, frex, that can (1) use the strongest human muscles, (2) leverage body weight as part of the energy input and (3) combine the energy of multiple people at once.

But still - even in a no-modern-fuel situation - there are many better ways to go. Consider the variety of methods used before the industrial revolution to power machinery. Animals can run your same cranks, mills, screws, etc. much more efficiently than people - esp. when you consider that people can be more useful doing other things than supply pure muscle. And what about windmills & watermills? Those were revolutionary in their impact when they were developed in the middle ages, & once you know about them they're pretty straightforward to build & use on a large scale. Every river with a reliable flow used to be full of mills. Why would your people not be using them?
 

Michael Davis

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In WW II they used hand crank to gen energy for radios in pacific theater, but the capacity is very limited because the human body is restricted to what it can do (wattage wise). If you read many of the prepper sites you'll see many alternative to petrol based that actually work and are viable for same enough to produce, say 1-2 KW of juice which can run a small house. It's technology that actually works and many are installing given they think doomsday in over the horizon (they all work):

- Wood gas (burns work in chamber, incomplete combustion creates flammable gas for generator)

- Steam engine (search You tube for videos of home made units)

- Ram water pumps for electricity

- Windmills

- Propane (LP can be stored indefinitely, unlike petro gas which degrades in about a year, even with stabilizers). Have a friend with 2 1000 gal tanks that can run his house (minus heat in winter) for 5-6 years)

- Solar panels (Half life of the type with great longevity is 30 years)

Hope that helps.
 

ClareGreen

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I'm with Waylander - watermills are the obvious choice, followed by windmills for anywhere too flat to have much water flow. Solar could work, but requires a chunk of tech to set up (unless we're talking black hosepipe in a greenhouse sort of solar). Solid fuel fires could be done, as could steam, but those would need a lot of care and attention that windmills and watermills generally don't.

A lot is going to depend on the tech levels available. Water wheels and windmills are easy, while water turbines need a certain level of technology. If you have a surviving engineer (or textbooks), though, you get a huge head-start on what our ancestors had to work out for themselves.

There are small hand-wound radios with batteries and tiny solar panels to help extend the charge, but they wouldn't help much with broadcasting.
 

Quinn_Inuit

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I also recommend considering how dynamos work: http://www.wisegeek.org/what-is-a-dynamo.htm

Here's a fun setup:
Guy on bicycle powers a driveshaft, the power of which is magnified with gears, belts, or both to spin a magnet. (So it's hard to start up, but will rotate like crazy once going.) Maybe even take advantage of the gearshift from an old bike to change the difficulty level when you're just starting to pedal? Not sure that's do-able.

Anyway, once you've got that sucker going, you can keep producing power almost indefinitely if you can keep swapping out the riders. Maybe have a clutch gear that can be used to disengage the mechanism while you're swapping riders.

That reminds me of watching an Electric Amish concert in high school. They had a guy they called "Brother Yoder" riding a stationary bike on stage the whole time they were playing, which they claimed powered their instruments. :) It was awesome.
 

AlyssaCroft

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Thank you so, so much for all your input, everyone! You've all given me juicy details for me to look into.

I want to steer away from anything that would be easy to spot (these people try to stay relatively hidden), so big windmills or watermills are probably out. But I could definitely use something like what they use for tides and perhaps small dams.
Will do more research into all the suggestions here. :D

Thanks again everyone, you're awesome!
 

jaksen

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I had a student (retired teacher here) whose entire home was powered by a water wheel. Their house was next to a fast-flowing stream and the entire powerhouse, wheel, generator, etc. was all built by the student's father.

They sold their extra power to the local power company.

This is a family of four with ordinary electrical 'needs,' for cooking, running appliances, etc. They were matter-of-fact about it, yeah we have a powerhouse; yeah it runs just about anything in the house we need.
 

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In your question you also asked about storing energy in something other than batteries correct?

It is possible to store energy in heat, pressure or potential mechanical energy with the use of gravity. For example when you generate electricity you can transfer it into mechanical motion such as moving water or sand to a higher position. You can then let the water or sand drop at a certain rate and let the force generate other mechanical energy that can in turn be transferred into electricity.

The thing to remember when coming up with something clever for generating power is that electricity is a form of energy that is always transferred from something else. If you look around you people are forever changing forms of energy into something that they can use be it electricity, heat, pressure, motion, etc. Energy is never lost, but always changes.

I hope that helps you with your research.
 
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redfalcon

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If the husks of automobiles are available, hooking an alternator to a propeller or "whirlybird turbine", will charge a battery. The 12volt system will power anything you can find in a car, and is relatively portable.

I don't think any thing taking human power would be to popular for day to day needs. Calories vs watts is a bad trade off.
 

Kevans

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External combustion too. Small steam engines and dynamos can provide power in very compact packages, I build steam engines for fun, my latest was a V-6.

Regards,
Kevin

CIMG0131.jpg
 

blacbird

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heat, pressure, motion, etc. Energy is never lost, but always changes.

No, not lost, in the context of physics, but some is always wasted, in the context of practical industrial reality. You cannot get more out of a system than is put into it, regardless how how the form of that energy is altered in the process. This Newton guy figured that out 300 years ago, and not even Mr. Einsteen altered that basic thing.

caw
 

Megann

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No, not lost, in the context of physics, but some is always wasted, in the context of practical industrial reality. You cannot get more out of a system than is put into it, regardless how how the form of that energy is altered in the process. This Newton guy figured that out 300 years ago, and not even Mr. Einsteen altered that basic thing.

caw

Very true it is "wasted" in the sense that it becomes useless to us, mostly in the form of heat which can't be reclaimed a 100%, but it still exists.
 

Roxxsmom

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Human-powered hand cranks are a very limited and inefficient way to generate energy. Even if you restrict yourself to human-powered methods there are better ways to do it - large treadmills, frex, that can (1) use the strongest human muscles, (2) leverage body weight as part of the energy input and (3) combine the energy of multiple people at once.

But still - even in a no-modern-fuel situation - there are many better ways to go. Consider the variety of methods used before the industrial revolution to power machinery. Animals can run your same cranks, mills, screws, etc. much more efficiently than people - esp. when you consider that people can be more useful doing other things than supply pure muscle. And what about windmills & watermills? Those were revolutionary in their impact when they were developed in the middle ages, & once you know about them they're pretty straightforward to build & use on a large scale. Every river with a reliable flow used to be full of mills. Why would your people not be using them?

I was going to say something along these lines, but benbenberi beat me to it. I'd say water or wind mills are a good option, I think. Animal power might be useful for small amounts of power too, though of course you'll need lots of fodder to fuel their work.
 

AlyssaCroft

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External combustion too. Small steam engines and dynamos can provide power in very compact packages, I build steam engines for fun, my latest was a V-6.

That's awesome! I love it when folks tinker with "old" technologies like that. If you ever want to spam me with truckloads of info about your steam engines, I'm all ears! (er... eyes?)

I never actually considered steam. The environment holds a LOT of water (mostly marshy swamped environment- aka stillwater). I'll need to look into steam engines more, but basically as long as you have heat and pressure, you're set, right? I'm wondering if you could do some sort of rocket stove set up to heat things, as readily-available coal is out, but there'd be plenty of small plant growth (twigs, brush).

I feel so incredibly dumb with all this energy stuff. First-world problems, eh? I take for granted that when I flick a light switch, the light turns on. Never had the need to look into all the different ways we could make that happen.

Thanks again for all your responses! You've all given me lots of great tips to research. :D
 

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Human power will not translate to much electricity. In a post apocalyptic world, here's what I suggest:

1. Steam power. There is a way to convert a small gas motor over to steam. It ain't pretty or efficient or long lasting, but it'll work for a while.
2. Producer gas (wood gas) this gas will run a gasoline engine, with a slight adjustment to carb. A wood gasifier is the most common device to generate producer gas. One can be built from scrap, but it's extremely important to filter the tar out before going into the engine. Another option is a charcoal gasifier, which greatly reduces tar content. Very simple and cheap to build. Gary Gilmore has a great open source charcoal gasifier. Look him up.
Producer gas can run a generator or even a vehicle.
3. Solar panels. Your characters can get them off street signs, stop lights, businesses, homes, and utility companies with solar panel fields after the fall of civilization.
4. Wind turbines. Can be built from scrap.
5. Water turbine. Again, can be built from scrap.
6. Animal power. Horses, cows, dogs can generate electricity on mills.
7. Static electricity. Several thousand feet of HAM antenna wire, hung as high as you can get it, will collect static electricity from the breeze. To convert it for use charging batteries, attach an automotive spark plug to end of wire at ground level. Fire off into an automotive coil. Attach coil to positive terminal of a battery. (Negative terminal is grounded). High voltage, low current static electricity will fire off from the spark plug into the automotive coil when the charge has built up enough to cross the air gap. The automotive coil will lower the voltage and raise the current, which will then pulse into the battery. Battery gets pulse charged. 200 feet of wire will charge a 12 V battery in 2 days. 1,000 feet will charge it very quickly. Yes, this works.

8. Wave generators. These make electricity from the motion of waves in the ocean.
9. Fuel alcohol. Distilling alcohol to make fuel to run engines.
10. Bio-diesel. Made from food oil, biodiesel can run a diesel engine.
11. Hydrogen. Aluminum in an acid bath will separate hydrogen from oxygen without electrolysis or any other energy input. Hydrogen can run an engine. Very dangerous, though. Aluminum cans or scrap aluminum from just about anything can be used as the fuel source.
12. Magnesium and copper can be used in a plain water battery to provide a small charge for over a year. (Not salt water, it'll eat the magnesium quick). Several of these in parallel or series would provide a modest, but steady, amount of electricity for a long time.

In case there's no wood available for fire, bio-briquettes can be made from just about any available biomass. They burn similar to wood.

Rocket stoves would be ideal for cooking. They'll burn bio briquettes, no problem. Also, they don't smoke much at all. Easy to build, efficient, and clean.

In a SHTF situation or eotwawki, water would be heated with fire or solar, food would be cooked with fire or a solar oven or even a parabolic dish reflector. Clothes get washed by hand or possibly with an animal powered machine. Water would be pumped by hand, animal power, or a windmill. Or, water would be desalinated by fire or solar heat. Homes or shelters would be heated with fire.
Very little would run on electricity unless your characters were fortunate enough to have one of the items listed above.

You have a chance to show readers options for generating power off the grid. Show them something cool in your story. I'd recommend producer gas from a charcoal gasifier. Use the waste heat as it runs for cooking or water heating.

PM me if you have other questions about living or thriving in a post apocalyptic world. I can help or direct you to those who can. I love this type of fiction.
 

blacbird

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11. Hydrogen. Aluminum in an acid bath will separate hydrogen from oxygen without electrolysis or any other energy input. Hydrogen can run an engine. Very dangerous, though. Aluminum cans or scrap aluminum from just about anything can be used as the fuel source.

In a post-apocalypse society, where does the acid come from?

12. Magnesium and copper can be used in a plain water battery to provide a small charge for over a year. (Not salt water, it'll eat the magnesium quick). Several of these in parallel or series would provide a modest, but steady, amount of electricity for a long time.

In a post-apocalypse society, where does the magnesium come from?

caw
 

mangydawg

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Depends on the nature of the apocalypse and the amount of time passed after it happened. If it was disease that suddenly wiped out most of humanity, then magnesium and acid will be sitting on store shelves. Magnesium fire straters in the camping section. Acid at the hardware store.
Please note that these two methods are not sustainable in the long run. They're just chemical reactions that provide energy. The aluminum is eaten away by the acid. The magnesium will eventually erode in a water battery. For today's use, these are not solutions at all.

In a breakdown of society, these methods can get one by until folks begin coming back together in communities. Then, perhaps, they can set up for sustainable energy production.

Gasification, especially charcoal gasification, is a more sustainable option for a post apocalyptic world, assuming the disaster didn't wipe out all the trees. (For charcoal gasification, the waste heat from both making the charcoal and running the gasifier should be used. Also, the volitals that offgas during charcoal making should be piped back into the fire to reduce air pollution and for a more efficient burn process.). I'm an advocate of charcoal gasification over wood gasification in a survival situation due to the ease of equipment construction and operation. Both can work, though.

Frankly, electricity use should be replaced wherever possible in a bad situation. For myself, I'd use it only to charge electronics, not run my home as we do now. I think steam power would be used in a big way after a total collapse. In a situation like that, those who know how to produce energy will be worth their weight in gold, at least until they teach others to do it for themselves. I maintain that if folks have access to as much energy as they need, surviving will be much easier.

In a disaster that all but wipes out humanity and destroys all the buildings and remnants of technology, the survivors wouldn't be able to scavenge to repurpose parts, like vehicle alternators and engines, and energy production would be reduced and the means to produce it limited. I imagine solar, wind, and hydro would be used extensively.

What is your apocalypse scenario? What do the survivors have to work with? Where are they located---hot or cold climate, near or far from big cities, near or far from agricultural lands?

We would be better able to help if we had more details.