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Is pedal power cleaner, more durable, with less environmental impact than solar or wind?  RSS feed

 
master steward
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I've found I don't NEED much power, and I would love to find a way to move from petrol-based electricity, We get little sun on our north-faceing, tree-sheltered property, and very little wind, too. Every solar-powered device (lights, fence charger) have died after a winter (or three winters, in the case of the fence charger) on my property.

I've read quite a bit about the environmental destruction that comes from mining metals for solar panels, and how almost as much energy is used to manufacture these devices as they generate in their lifespans, especially if they're placed in sub-par locations.

So, I've been looking into pedal power. My brain just can't forget that scene in Soylent Green where they power a lightbulb with a bike. My brain can't help but think that advances in bicycle-powered technology must have advanced.



I would love to be able to power my energy efficient freezer (if I added insulation to it, it should be even more efficient) and my well pump in the case of an emergency. That's really all I need. I like that many pedal-power generators do not (if I understand correctly) require a battery and can be used directly to power appliances. I like that some can even be plugged straight into a on-grid system to add power as you bike.

I've found some interesting plans and products on the internet.


David Butcher's Pedal Powered Generator: Plans are $50, and it uses a f;y wheel to even out the power so there are less surges. Supposedly, material costs are only $230.00, and a lot of used materials can be re-purposed for this.There's no way that I can see to change the gear to pedal harder to get more power in a shorter time. The riding looks easy, and seems to be about 50 watts/hour.



The Green Microgym: Costs $1,100 and comes with a way to plug straight into your house to power your house, or to plug devices in individually. Comes with the inverter to change it from D/C to A/C. You can attach it to a normal bike and use the gearing to make it easier or harder to pedal, and therefore the amount of power you can generate in a given set of time. Can generate up to 500 watts/hour, though most people would only be getting 50-100 watts.



Using a tredmill generator hooked up via belt to one's bike: This seems to only have one "gear": HARD. Looks pretty affordable to make, though.



Pedal-a-Watt: Price starts at $369.00, but that's without anything to connect it to a house or appliance. Once you add those in, it's more like $800. I don't know if you can gear up and down, but I'm assuming so since it says it can generate up to 400watts, and that'd be hard to do without gearing.


From an NPR article on the subject (Could You Power Your Home With A Bike?)

Consider this. For all of human history the amount of power the average person had to expend across each day was, well, one person-power's worth.

Duh.

And how much was that in terms of energy? Well, our little bike example gives us a good estimate: Eight hours of biking per day yields 800 Wh (0.8 kWh). So since the dawn of our species 300,000 years ago, 0.8 kWh was pretty much the energy available to pretty much everybody each day. If you personally wanted more energy you would need to buy someone else's person-power in the form of servants or, worse, enslaved populations.




My freezer uses just under 100 watts/day--if I'm understanding the numbers right. So, an hour of bicycling could keep my food frozen until I need it, espeically if I insulate it well. I know there are ways to live without a freezer, but I don't think I'm at that stage right now, and we currently store a lot of clearance meat and frozen berries in there. I'd hate to lose all of that.


My main concerns/questions are:

(1) Will an investment in a pedal-powered generator pay off?
(2) What are the materials used to make the generator and how much negative environmental and human impact do they have to manufacture?
(3) How many watts of energy went into making a generator, vs how many come out of it in it's lifespan?
 
pollinator
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I haven't looked into the comparison of materials or energy between solar or wind vs a pedal generator, but I'd be looking at a couple of other aspects as well.  First, it's not easy to produce energy by pedalling.  It's doable, sure, but it gets old fast.  Second, who pedals when you're sick?  Third, buying something that passively creates energy is just good management.  If you've got hours a day and nothing to do, that's one thing, but if you don't, you're into resource management (your time) territory.  

I understand you're thinking of an emergency, but I'd rather spend that kind of money on a system that I can make use of for whatever and then re-purpose it for emergencies.  If you set it up to power your pump and/or your freezer every day, it'll at least start paying for itself in energy savings.  You'll also know if it's working or not, can bypass it when it's not for repair, and you'll never find yourself in an emergency and discover that something is wrong and your solution for emerg power doesn't work.

I think it's great to think about, though, whatever you decide.
 
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Hi Nicole;  
All excellent questions.  
I think even with pedal power you would want some type of battery, and (sorry) but a backup propane generator.
#1) Yes, I believe a reasonable amount spent would repay itself.
#2)I can't directly answer that one, other than to say this is small manufacture stuff. So probably not a huge environmental impact.
#3) I'm guessing again but pretty sure you get more out than was used to make it.


Now my rebuttal or a dose of reality.

Pedal power requires someone to pedal it … a lot...
You are a busy mom , could you stop everything to pedal the bike ? For several hours at a time ? If your child needed you in some way, I'm sure that pedaling for the freezer would have to wait...
Could be your children would try it for a while, but I promise they would tire of it very quickly.
In a worse case power outage scenario , this could be a stop gap measure,  until utility's came back on line.

As a way to teach your children about power production and power usage it could be a great tool.
Pedal the bike for an hour , produce the power to play their games for an hour.
 
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Hi Nichole,

I looked at this option briefly for opening an exercise gym where the gym supplied me power ....and maybe surplus electricity.

I've pedaled one version of a pedal for electric power and it was REALLY hard (but it didn't have 21 gears either) and the electricity flow ended as soon as muscles stopped contracting (no fly wheel).

Without having done the calculations with a very large and massive fly wheel, I still believe it is possible...get the flywheel up to speed where its inertia is just above the inertia of the electric generator then put a load on the generator.... Intuitively I believe the flywheel should be 6 to 8' in diameter (the gym would've had a much larger one hidden in a 15 foot wall), and very massive.... I'm working on thru the wall solar oven solar plans right now but here are some formulas to help you get an idea:

moment of inertia for a solid disk (flywheel) = 1/2 (mass) * r^2   where r is the distance from the center of your flywheel to it's outter edge.

the amount of torque to turn the flywheel = Moment of inertia * acceleration = (1/2 mass * r^2) * radians/second

here is a site with a sample problem for you: see torque Calculation section

this would be without gears.....and you need a way for you to know what a foot pound or a newton meter feels like to your legs


wow, didn't answer any of your three questions did I?   1) it won't if it's too hard to pedal cause you won't be able to use it; 2) copper, coating to cover the copper for the motor windings BUT here in the USA this is free if you find a working old electric motor in your wattage range; 3) I'd have to do some serious googling for how many joules it takes to  make an electric motor out of copper wire and the life span of a brushless electric motor plus the metal bike, gears and the number of chains that would need to be replaced
 
pollinator
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I would really check that freezer W usage that sounds like an hourly usage/max draw not a daily usage figure. The fridge in this house which is only two years old and A rated uses 120kwh per year which works out at 328W a day. (my chest freezer is older than sin so has no figures on it!)

I think it would be really cool to get it set up to charge small devices; phones, tablets etc Possibly even a TV that would be a good way to get fit, no peddling no watching! I really like the idea as a way to get fit, as a backup electricity idea or a money saver I am not so sure.

The main problem I think would be how much power you can generate at one time, so if your freezer uses 100W it probably will not run at all on 50W varying power production may also be a problem

so your questions,
1. how much does your power cost? assume 50W is what you can peddle, that's 5% of 1KW (for me at 30c a KWh each hour peddled on the bike would save me 1.5c meaning that $800 set up would take 53333 hours to pay back!) of course if you are fitter than me and can manage 100w then it'll only take 3 years of constant peddling if your electric also cost 30c per KWh
2. that's really going to depend on how much reused stuff you can work in.
3. almost certainly more in it's creation, but if it's a reused bike that you save from the skip, it's still a net gain.


(can someone check my maths I confused myself with W and W hours the payback time sounds ridiculous)
 
Timothy Markus
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There's also a big spike in energy in order to get the compressor started.  They have capacitors to help smooth it out, but you'll need enough to get it going and may not be able to without a battery.
 
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(1) Will an investment in a pedal-powered generator pay off?

It depends. Too many variables to give a definite answer. It's possible to make one from spare parts for almost nothing. Or spend too much on something commercially made. If it saved a freezer full of food during a storm it seems worth it. Also if it kept someone's insulin cold during the same storm. Years ago a friend converted a bicycle into a generator. If his kids wanted to watch tv they had to pedal to charge a small battery. It didn't last long if they stopped pedaling. That was with a CRT TV which consumes considerably more power than a modern flat screen TV. He thought it was well worth it.


(2) What are the materials used to make the generator and how much negative environmental and human impact do they have to manufacture?

The materials are much less toxic compared to making a computer or cell phone, for example. The metals commonly used are iron, steel, nickel, chromium, & copper for the internal parts. Perhaps tiny amounts of brass &/or zinc. Most likely an aluminum alloy for the outer case. Maybe a couple drops of lead solder. Carbon is used for the brushes. Nothing too exotic & no rare earths in common generators. I'm sure there are some very expensive exceptions for specialized uses. There are also some insulating materials used. Rubber, plastic, phenolics, epoxies, etc. Those are probably the worst components from an environmental & human perspective.


(3) How many watts of energy went into making a generator, vs how many come out of it in it's lifespan?

To clarify ... electrical energy is expressed as watt-hours or joules. Watts is the unit of measure for power. Energy takes into account time but power is an instantaneous value. Energy = power x time.

That's a really good question. I'm guessing that over the course of a generator's lifetime it produces more than it requires to manufacture the generator. I'm basing that guess on economy of scale of manufacturing & I think they would be much more expensive otherwise. Never thought of this before. Will try to find an accurate answer. Aluminum might be the game changer. That requires a massive amount of energy to produce.
 
Nicole Alderman
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Timothy Markus wrote:I haven't looked into the comparison of materials or energy between solar or wind vs a pedal generator, but I'd be looking at a couple of other aspects as well.  First, it's not easy to produce energy by pedalling.  It's doable, sure, but it gets old fast.  Second, who pedals when you're sick?  Third, buying something that passively creates energy is just good management.  If you've got hours a day and nothing to do, that's one thing, but if you don't, you're into resource management (your time) territory.  



My problem is that there's nothing that will passively create power here. We get very little wind, being sheltered on all sides by trees. I can't even fly a kite, and the tree tops don't even move that much in the wind! And, during the winter, the sunniest area of our property gets maybe 2 hours of direct sunlight. Even in the summer, we don't get that much sunlight--I can only dry my clothes outside for 1/2 the year--the rest of the time it's too dark too soon for clothes to dry.

And yeah, I was thinking about how difficult it would be to run when injured or sick. I like riding bikes, and I can ride and read stories to my kids at the same time, or ride and needle felt at the same time, if I go slow enough. Or ride when watching a show, though we don't do that very often. I like the idea of the Green Microgym because it can be plugged into the system directly, or switched easily to powering a device.

thomas rubino wrote: I think even with pedal power you would want some type of battery, and (sorry) but a backup propane generator



We do have a gas generator, which is what we currently use during power outages to keep our freezer from thawing. It's stinky and loud, and in the case of the big 9.0+ earthquake that we're due here, I'm pretty sure I wouldn't be getting any more gasoline for a while. We've got at least 2 months of non-perishable food in our house, but man, it'd stink (literally and figuratively!) to have to deal with that freezer thawing. The amount of time I'd be spending trying to somehow preserve it all on a woodstove would be insane--a lot more crazy than riding a bike for an hour while reading story after story to my kids! And the time I'd be spending trying to haul, boil, and filter water would probably be a lot more than just riding my bike enough to fill my pressure tank to have running cold water in my house

As a way to teach your children about power production and power usage it could be a great tool.
Pedal the bike for an hour , produce the power to play their games for an hour.  



Tee hee! I like this idea! My kids are always wanting to watch videos and play computer games. They do great when they're outside, but whenever we're near a screen, we're drawn like zombies toward braaaaaaaains...because our brains are gone!

My main conundrum is trying to figure out where to put the thing. The garage, by the freezer makes a lot of sense, but, then they couldn't watch a scene while they bike. Also, how do I make it something that both my husband and I can ride, and my 5 year old son, ha!


Skandi Rogers wrote:1. how much does your power cost? assume 50W is what you can peddle, that's 5% of 1KW (for me at 30c a KWh each hour peddled on the bike would save me 1.5c meaning that $800 set up would take 53333 hours to pay back!) of course if you are fitter than me and can manage 100w then it'll only take 3 years of constant peddling if your electric also cost 30c per KWh  



So, I went and grabbed my bill, and it's $0.10321/kwh, so 10cents. My husband has beefy biking legs, and I might be able to persuade him to bike some. Let's put us at an average of 100w, So, 9 years, biking an hour a day, right? That's a long time!

(Looking at my bill and seeing how many KWH we use in a month is depressing, and I'm going to go order one of those Kill-a-Watt things. Why are we using 1,000kwh per month? That's the average amount that a US household uses, and it's depressing that that is my number! Is it the 175 and 75 gallon aquariums my husband has running in the garage, or what?)

To clarify ... electrical energy is expressed as watt-hours or joules. Watts is the unit of measure for power. Energy takes into account time but power is an instantaneous value. Energy = power x time.



THANK YOU! No matter how hard I studied in school, the "hard" sciences (chemistry, physics) were always major weak points, and I don't know if they even ever covered watts. It's really frustrating for me, because mechanical stuff goes right over my head, no matter how hard I try to catch it. I'm going to be chanting "Energy = power x time" for a few weeks to hopefully drill it into my brain. (Don't mind me as a I mutter "speed = distance/time. Energy=power x time. Acceleration is change in speed. Velocity is pretty much speed. Gravity's terminal velocity is 122m/s. Power is work/time. ")
 
Nicole Alderman
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Timothy Markus wrote:There's also a big spike in energy in order to get the compressor started.  They have capacitors to help smooth it out, but you'll need enough to get it going and may not be able to without a battery.



This question shows my total lack of knowledge, but is the compressor in the freezer? And the freezer has capacitors to help smooth out the spike of energy needed to start the compressor? I'm wondering if starting with a "sprint" would work. How long does it take to start the compressor?
 
Skandi Rogers
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Nicole Alderman wrote:
(Looking at my bill and seeing how many KWH we use in a month is depressing, and I'm going to go order one of those Kill-a-Watt things. Why are we using 1,000kwh per month? That's the average amount that a US household uses, and it's depressing that that is my number! Is it the 175 and 75 gallon aquariums my husband has running in the garage, or what?)



This one made me giggle.. I'm the same. What we use the average? What are we doing, stop it Got to be better than the average! I don't know about our electric consumption actually, I'll have to ask him when he gets up from his nap, I see that 335kwh is average for a month here. but I know we use 52m2 water in a year which is about 30% less than average and we have a garden that gets watered on occasion, I doubt our electric use is so good.
 
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Many years ago at some energy fair I got a chance to ride a bike generator sort of rig.  It was set up pretty basic such that your pedaling created 12 volt DC power.  Then once you got pedaling they would flip a switch directly connecting the power you were generating to a 12 volt car headlight.  As I recall the point of it was to demonstrate in a physical body sense just how much power/work it takes to generate this little amount of electricity.  Initially with no load it was easy to pedal.  As soon as the switch was flipped and it was powering the light you understood what "load" meant!  Most people couldn't keep up the pedaling for more than a couple minutes.  I think I did it for 5 minutes or so, but it was SERIOUS work.

I know, you are probably thinking right now about how using gearing would reduce how hard it is, and you are sort of right.  With the right gearing it would be easier to pedal, but the critical point is that you would be generating less power then.  Consider when riding a bike uphill.  In my high gear, 21st, if I have the strength needed to turn the pedals it won't take too many revolutions of those pedals to get up the hill, but it is really hard pedaling.  In my lowest gear, 1st, it's easy for me to rotate the pedals, however I'm also barely moving the bike any distance for each rotation.  The gearing is simply allowing me to focus my power over a shorter distance.  What it is NOT doing is allowing me to generate more power.

Another thing to consider is that even if you only need 100 watts a day to power your freezer you will need to generate more than that to allow for all the losses involved in the system storing it in batteries and transforming it from DC to AC, etc.

I do think such a system would be interesting to have, and certainly educational about just how much energy fossil fuel, and the sun give us in terms of raw power.  I suspect as a functional way to supply any serious amount of power though I'm guessing it won't be all that grand.  Now if you are looking to get an exercise bike to use for the exercise it does seem like a neat idea to utilize this for the resistance load and thus get some functional "work" out of the exercise time.
 
Mike Barkley
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Try this technique to estimate the work required to operate any given electrical device. 750watts = 1 horsepower. (approximately)

Randomly volunteered this small freezer. Spec is 75 watts. One tenth of a horse.

The most common hair dryer spec seems to be 1875watts. Two & a half horses.
 
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I've always been keen on pedal power, but after watching this video..... hmmmm.  I do like toast in the morning.....but not this much! https://www.youtube.com/watch?v=S4O5voOCqAQ
 
thomas rubino
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Thank You Gary;  There we have it.  Even in my teens I never looked like Robert...  guess toast is out..
 
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I think such a setup would be excellent in a pinch. I wouldn't want to try and supplement my household's power generation with one though, unless working out was already a part of the daily routine.

I mean, if someone's burning the calories every day anyways, why not capture some of it? It may, depending on the number of people participating and the duration and intensity of their workout(s), actually generate quite a bit.

And in the event that other power sources are unavailable, as long as you have sufficient quantities of high-calorie food, you can easily generate enough power to do things like charge batteries for cordless tools, power communications devices, and maybe even power a small fridge reliably.

I don't really think you can compare pedal power with solar or wind power generation; each is most suitable in situations specific to its own design. Solar and wind, though, are directly and indirectly powered by the sun's impact on our little blue marble, whereas the same is true for pedal power, but there are more conversion losses, from sun to plant to food to caloric, then kinetic, energy, and finally to electricity.

But if this were the best way to generate power, I wouldn't even think about electricity first. I would think about a giant flywheel, and what it would take to build one on magnetic bearings and in a sealed chamber with the air pumped out by its' own operation. If you could build such a construct, you could spool it up gradually, increasing the gear ratio on your bike as needed, though I suspect that at least one additional set of sprockets would be necessary to really take advantage of the spinning-mass-in-a-near-vacuum idea.

Then if electricity was really the currency of energy you required, the flywheel and vacuum casing could be designed as stator and armature for a giant generator. I suspect that a giant PTO could be designed for the wheel, for direct mechanical power, but such a need would be highly specialised in a stationary capacity.

I am looking for the article, but I fear it was in a Popular Science whose subscription I am no longer purchasing, but it detailed a newly designed and built bicycle with ceramic parts and a beltless, chainless design, basically a series of sprockets in a casing connecting the flywheel to the rear sprocket. It was so efficient that as soon as the travelling speed effectively cancelled out the bike and riders' momentum, the overall mechanical efficiency exceeded 90%, iirc.

This would literally be game-changing for the discussion about pedal efficiency. Couple that with the frictionless flywheel generator, and stationary, small-scale power generation could forever be revolutionised. Imagine, in addition to a hyper-efficient bicycle auxiliary, that these frictionless flywheel generators were powered by intermittent sources like solar or wind, or like millponds that fill seasonally and/or by wind pump.

Also, imagine the hyper-efficient ceramic sprocket set transmission setting bicycle mechanics free. How would energy usage change if suddenly the human body could be used to directly power some machinery at ridiculously high efficiency? Would we even need cars if, by switching off, or by having all passengers pedal lightly, a pedal car could do all the things an internal combustion engine or electric car could?

Imagine a pedal-powered garden tractor, where you sat and pedalled, and the machine beneath you was efficient enough that it could operate all your garden equipment with just that, powering the accessories, occasionally crawling forward, and no noise or stink but your own grunting and sweating and the whir and clang of the tractor.

I could even see a treadle-powered or walking-beam design, powered by the bouncing of children. You'd need to be a master kid-wrangler, but if you could either get them running in a small mob up a beam that constantly falls with their weight, then back again, perhaps with a box of doughnuts on a tether, swinging towards the end in the air, or the group halved and jumping in sequence on either end of the beam, that could generate a lot of power too.

-CK
 
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James May and his team built a Swiss Army bike on the series Man Lab. I couldn't find the whole programme but...
https://youtu.be/uIfbY5G79I4
https://youtu.be/B5dLE8lVovI
This next piece is of an Indian knife grinder. These were common in Spain up until relatively recently. Sadly now they use cars, but in a hotel near us there is an exhibition of the progression of itinerant knife grinders through the years.
https://youtu.be/wLnziyaEXIo
When I lived on Mallorca, you would hear the funny bird-like call the knifegrinder made as he passed through the villages,  and chefs from the bars would come out with their knives and locals with scissors or mowing blades.
 
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Nicole, when I think of pedal-power I do not think of electricity. When you mentioned pumping water, I thought it would be more effective to have something with pedals that moves the water than to make electricity first. For a freezer this won't work, of course.
I found this article in Dutch on a kitchen machine on pedal power (without electricity). Watch the photo to know what I mean.
https://www.lowtechmagazine.be/2011/05/een-hightech-keuken-zonder-elektriciteit.html
 
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Is pedal power cleaner, more durable, with less environmental impact than solar or wind?

My feeling is that the answer is generally "no", except in very niche situations. My logic goes like this.

Using a bike to generate power is both tiring and time consuming. If you commit to two hour per day to eg charge a phone, charge simple battery lights etc... that is two hours you can't use for more productive endeavours like gardening, cooking, cleaning etc... Realistically it's use is going to be small as a result, as there are always demands on people's time. And if you have a strenuous day of work ahead you need your energy for that, not pedaling! So, over its life time, the device is going to be used comparatively little (lets say 1 hour in every 24) and the wattage produced is going to be low limited by what people can sustain (100W?)

On the other hand a wind turbine, or solar - even very small scale ones - have much greater up time (10 hrs per day?) and potentially much greater productive potential (1000W?). Plus they don't need to have a person chained to them pedaling, which frees us up to do more valuable things. The pedal bike - even assuming it is used every day - produces 1/100th the power of even a very small solar/wind setup, and still needs regular maintenance, and needs a whole host of electronics to convert power to something useful.

This feels to me much like the "wind up torches" that my well meaning family keep on giving me "for camping". They weigh more (I like to pack very light), have less bright light, need winding every few minutes, are noisy and cumbersome to use etc... They are simply less good than a head torch with rechargeable batteries that gives me 100+ hours of light for reading or cooking. And when I think about the times that I need or want a torch they are always the times when I need my hands free - when cooking or eating, or trying to put my boots on in the dark. The headline of "wind up power" doesn't even come close to matching the convenience of a fully recharged battery at the start of the week.
 
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I found this and several other examples that were close when I went looking to see how much power a cyclist produces in an hour. The first figure is for someone who is going to enter races.

A trained cyclist can produce about 400 watts of mechanical power for an hour or more, but adults of good average fitness average between 50 and 150 watts for an hour of vigorous exercise.

I don't think there's a chance that you could provide a long enough sustained effort to operate your freezer. My RV style washing machine used is 240 watts. I might be able to make it operate for 15 minutes.

I think it would be much more useful for you to look at ways to conserve energy. I understand your husband drives to work for half an hour or so. If he was to drive 5% slower, that would save an amount of energy equal to many times your daily output.
 
Nicole Alderman
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Michael Cox wrote:This feels to me much like the "wind up torches" that my well meaning family keep on giving me "for camping". They weigh more (I like to pack very light), have less bright light, need winding every few minutes, are noisy and cumbersome to use etc... They are simply less good than a head torch with rechargeable batteries that gives me 100+ hours of light for reading or cooking. And when I think about the times that I need or want a torch they are always the times when I need my hands free - when cooking or eating, or trying to put my boots on in the dark. The headline of "wind up power" doesn't even come close to matching the convenience of a fully recharged battery at the start of the week.



The funny thing is, it was those hand-crank lights and radios that got me thinking of bike power. The solar panel on them dies after a year or two, and batteries can run out, but the hand-crank mechanism always works! Sometimes they stop working unless you are actively cranking them, but at least they always work! I have a little Coghlanshand-crank flashlight. It's tiny (an inch long), light weight, and dynamo, so there's no batteries. I crank that little thing for a while, and it's enough light for me to navigate around my house.



Of course, if I'm cranking something by hand, I can't do something else. But, with a bicycle, I could conceivably knit or read or needle felt or maybe even whittle while pedaling. This would, of course, be determined by how HARD I needed to pedal. If I'm pedaling as hard as that guy trying to charge his battery through a treadmill motor, well, I sure wouldn't be able to do something with my hands.

But, if I had the fly wheel like David Butcher's creation has, he's not working that hard, and powering a computer and a laptop and more.





I don't know much about dynamo technology. Would there be a way to connect a dynamo to a pedal power generator?


Supposedly, the Green Microgym uses flywheel technology. Though, their newer model doesn't look like it has one....but maybe I just don't know exactly what I'm looking for.
 
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I was going to post that olympic sprint cyclist toasting bread video, it gives a good idea of just how much power is needed for certain devices. Using a battery becomes a necessity for certain tasks, so that you can recharge the battery at a manageable pace, and then use the higher power output for a given device.

I used to have an app which was closely tied to a bicycle trainer I have which provided a pretty accurate power estimate, and was used for workouts designed to improve cardiovascular function and would track heart rate during the workouts, and the software would adjust workouts so that you'd reach the target heart rates each time. I stopped using it when they upped the price from $5/month to $15/month a while back, but I recall it taking me up to around 200 watts for the harder parts for around 5 minutes, then back to 100 watts for the easier 5 minutes. 100-150 watts would be a manageable pace for say an hour or two, if you already planned to be sitting around to say read a book or to improve your cardio.

If you have access to possibly a welder and Craigslist, you could make a custom setup for fairly low cost. An upright bike is inconvenient/uncomfortable compared to a recumbent seating position, so I would aim for a custom build. You can get the DC motor from a used treadmill or scooter etc weld it to a heavy flywheel and a single gear, or just use a belt from the rear bike wheel to the motor. Then take a used 12 speed bike, mount that bike frame (weld it, bolt it down etc) to a frame which also has something comfy to sit on in a slightly reclined position so that your feet reach the bike pedals comfortably and almost fully extends your legs as you pedal. You also solidly attach the motor to the frame and to the bike wheel so it spins as you pedal.

The gearing allows the pedaling to start easy and as you speed it up you can shift gears until you hit something comfortable on any given day. At one point I had a recumbent trike attached to my trainer, and set up my PC so I could play computer games while I pedaled the bike. It wasn't charging anything, just burning calories, but it worked. The reclined seating made all the difference.

 
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Interesting replies. The average I have used in the past is 150w Hr for a cyclist over a 1 hour period. I have numbers for a 6cu ft chest freezer converted to a fridge that says 175W Hr and my 12 volt shurflo pump uses 96W/hr pumping 2 Gallons per minute. If you were to go this route a battery thrown into the mix would be the way to do it so you could store whatever you were not using that instant and allow for compressors starting up and down time.
Nicole I can't tell you about the total environmental cost of making solar panels but I can tell you that when people talk about solar only lasting a few years generally they mean consumer products not power equipment. I have a 20 year old inverter still chugging along and come across 25 year old panels still outputting 80 percent of their sticker ratings.If you gave me a corner that gets 2 hrs of sun in the winter you would have the equivalent of 4 hours of cycling for less than $800. The battery would wear out in 7 to 10 years but it is fully recyclable, the panels at least 25 and the charge controller 10-20. The trick to shady areas is name brand gear and good design. 10 years ago partial shade was trickier but with higher voltage panels and better charge controllers its gotten easier.
Cheers,  David
 
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The number I remember from grade school is from the first pedal powered flights.  And athlete in good shape could do a sustained 1/10 of a hp following the sprint effort necessary to get the plane off the ground.  So using those numbers that would mean probably you were aiming at 75 watts output.  Now that doesn't mean you have be able to power the appliance 1 to 1.  Add a set of super capacitors to store the charge and then power the appliance in a burst mode.  Pedal for 2 hours and run the appliance for 10 minutes if needed.  While super capacitors are a bit more expensive than a battery they also are lower loss rate during charge and discharge and every watt counts in this endeavor.

 
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Has anyone mentioned yet that you will burn more calories with all that pedalling and will perhaps require an even bigger freezer full of food to get through the winter/earthquake?
 
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The humoristic part of me can see the scene where my wife paddaling power to the TV and me sitting in the sofa watching football,drinking beer and eating potatochips.
 
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Rita Vail wrote:Has anyone mentioned yet that you will burn more calories with all that pedalling and will perhaps require an even bigger freezer full of food to get through the winter/earthquake?



That is a good thought! Though, at least food is a renewable resource. Most of what is in our freezer is meat, which without the freezer and stuck on our property, the only protein I'd have for my kids is eggs...which there would likely be a whole lot less of, since the ducks wouldn't be getting supplemental feed. We do have crazy amounts of nasty-tasting canned salmon, which hopefully I'd be able to convince them to eat, LOL!

I'd like to use a bike powered generator both in and out of disasters. Because, at least, food is a renewable resource. It makes a good backup for disasters to keep the food frozen long enough for us to eat it before it spoils and we're stuck with a lot of rotting food to bury and the wrappers that the food is in to back up and store...somewhere where the bears won't smell the meat and come investigating.
 
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Another option is canning food rather than freezing it, lots of examples on Youtube of people canning meat separately as well as with veggies, "stew in a jar" style. Lacto fermentation with some salt (or real whey if you want to get fancy) can be used to preserve foods for several months also. This way you minimize the need for the freezer, and the electricity to keep it running.
 
Michael Cox
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Of course, in off grid situations it may be better to use a different starting point for your refrigeration needs. Conventional compressor driven systems are not the only way. You can also power a fridge with a heat source using absorption cooling. This is a much more appropriate system for off grid, as the heat source could in theory be anything - like a 10 minute burn of a mini-rocket stove.

https://en.wikipedia.org/wiki/Absorption_refrigerator
 
Dale Hodgins
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As already noted, the human body can only produce so much power. But there is a way to multiply that. If you're trying to compete with the electric company, the best you can hope for is 100% And that's just a hope.

I don't know whether you have room to expand your garden space. Imagine if instead of expending 500 watt hours of your energy to save a couple cents on power, you put that same amount of energy into expanding your garden and planting potatoes or any number of other things. I could see putting 500 watts into that and getting 5000 watts of food energy back. Then consider the amount of fuel that would have been burned to bring that food to you through other means. A huge savings. And even if you already have far more potatoes than you need, sell them to your neighbors and reduce their footprint. Just about any useful thing you put your time into, will pay back more than if you use your body to compete with the mega engines at the power company.
 
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I would definitely check the freezer watts first. The freezer I have is a fairly efficient one and it uses 100 watts in an hour, and needs to be on for at least 3-5 hours a day to keep things at sort-of-frozen temperature.

Standard household freezers also have an initial surge of around 5x their normal watts, and that is really hard on a small battery bank, and I'm not sure if it's possible to do that at all with pedal power.

From what I've read, camping freezers don't have this surge at start up though, and use less watts, some that I have been looking at use 50-65 watts an hour, and are designed to be left overnight without power, but they are also a lot smaller than normal freezers, and more expensive.

It's been a gloomy day here today, with only around 30 watts an hour coming into our 1300 watts of solar panels, so I am wondering if pedal power might help a bit on days like this. We have been grinding all our bread grain with a hand mill for the past couple of months and I think there is a human effort aspect of sustainability to consider too - whether you will be around to pedal when it's needed, or too busy with other things, and also it's not nice to have to do hard work like this when sick, or at the end of a long day away from home.
 
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The most efficient way is to eliminate the electric generator and electric motor. It means that you have to connect your pump and freezer compressor directly to your bike. There is approx. 10% loses on electric motors and 10 % on generator. So that's 20% savings on your power.
 
Dale Hodgins
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Yes and that's in a best-case scenario. Realistically, with your efforts going up and down and all over the place, it's not likely to be 80% efficient. Electric motors care about fluctuations of input energy. Compressors are much more forgiving. It doesn't really matter if one designed for 80 RPS is moving at 100 or at 60. They still work and it won't ruin them.
 
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And if you have to use an inverter that's another 7 , 8 % loss. A reciprocating pump just like the compressor, wont care about RPM's as well. If it were mine however. I will make a gym like machine: Bike Run, row, weight lifting all connected to the same device that I want to run. That way I get a complete workout too.:)
 
Of course, I found a very beautiful couch. Definitely. And this tiny ad:
Soil Testing: Genius or Snapshot of the ever-changing?
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