Can a clock be used to generate energy?

[Stovemaker]

Hello, i realise that this is an unusual question, but i am trying to make a wind-up stove. Yes, a stove. I wonder, could i use a clock , then add gears to increase rotation speed and finally add some sort of dynamo to it? Or would the cogwheel not have enough driving power and should i use a sort of music box srimg mechanism? Any help would be greatly appreciated..

[Klassiker]

Do you want to use the energy stored in a spring to generate heat for cooking?

[nevenbekriev]

10 hours ago, Stovemaker said:

Hello, i realise that this is an unusual question, but i am trying to make a wind-up stove. Yes, a stove. I wonder, could i use a clock , then add gears to increase rotation speed and finally add some sort of dynamo to it? Or would the cogwheel not have enough driving power and should i use a sort of music box srimg mechanism? Any help would be greatly appreciated..

I am afraid You will need to use a car engine.

[HectorLooi]

I don't get it. Are you trying to use the mainspring to power a fan to stoke the fire or are you trying to somehow generate heat?

[Neverenoughwatches]

12 hours ago, Stovemaker said:

Hello, i realise that this is an unusual question, but i am trying to make a wind-up stove. Yes, a stove. I wonder, could i use a clock , then add gears to increase rotation speed and finally add some sort of dynamo to it? Or would the cogwheel not have enough driving power and should i use a sort of music box srimg mechanism? Any help would be greatly appreciated..

You're going to need to produce a lot of energy to power a stove with any real heat so that is one big clockwork generator. Energy is not free as such, besides harnessing what the planet can provide.....Tesla suggested it...if it can self produce we certainly dont have access to it.....yet ..........in which case who's going to wind up this massive clock ? That would be a chemical to kinetic to thermal energy conversion. Intersting idea that my old boss once put to me....a clockwork generator to power a house. I think you're better to invest in letting nature produce your free energy....wind turbine ?

[JohnR725]

14 hours ago, Stovemaker said:

wind-up stove.

I think we would need some more operating parameters to really properly answer your question. So for instance how much power does the stove that you would like to power consume and then we can work with this and work out how to generate the power.

[Neverenoughwatches]

4 hours ago, JohnR725 said:

I think we would need some more operating parameters to really properly answer your question. So for instance how much power does the stove that you would like to power consume and then we can work with this and work out how to generate the power.

To cook fairly easily or to keep warm in a really small environment such as a smallish room to make it worth any time to build I'd have thought 2KW of electrical energy production, not sure what that would equate to in joules off the top of my head. As important as the production of heat into an environment is that of heat retention. A heavily insulated environment warms faster and retains heat for longer.....requiring less heat provision.  

[tomh207]

Just imagine the size of the mainspring and the hey to wind it up!

only clockwork mechanism I can think woul be any use would be to drive a fan to increase burn rate/efficiency but that would likely not be able to be run for long, at least not by anything a human could wind up.

 

Tom

[fellerts]

1 hour ago, Neverenoughwatches said:

2KW of electrical energy production

The very best athletes apparently output around 2 kW for short periods of time: https://sportsmedicine-open.springeropen.com/articles/10.1186/s40798-021-00341-7/figures/1. Unless your wind-up stove comes with a professional cyclist, I think this project might prove challenging.

[spectre6000]

22 hours ago, Stovemaker said:

could i use a clock , then add gears to increase rotation speed and finally add some sort of dynamo to it?

Yes. In a binary true/false sense, this is 100% possible. It's far from practical though.

In a pure energy transmission context, you're not wrong. However, you seem to be neglecting the energy requirements and source thereof. Energy has to come from somewhere. In a clock, that's a spring (typically, and for the sake of simplicity in this context). The energy from the spring is passed through the gear train to oscillate the balance, and en route turns hands to indicate the passage of time. If you have additional complications, a chronograph say, you have to increase the strength of the spring to accommodate the additional work being done moving additional hands or dials or what have you. In this instance, the complication is heat generation. You need a commensurate increase in spring strength.

Heat energy is pretty intense, and the energy used to power a clock is, by comparison, infinitesimal. The oven will operate in terms of kilowatt hours (typically 2-3 kWh/hr according to google), where the watch spring will be measured in microjoules; 1 kWh = 3,600,000,000,000 uJ. A quick google says the mainspring in a 2824-2 (an extremely common modern movement) stores 33,000 uJ. By the time you got a spring significant enough (at least 8 orders of magnitude) to make a dent in the heat generation requirements of a stove, it wouldn't be in any way recognizable as a clock (edit: actually, the 2824-2 is a watch movement. I do watches, not clocks, and those are the terms I think/operate in. A clock spring would be bigger/stronger, but not meaningfully so in this context, and I'm not going to go back through and redo the math for this sort of thing). The spring would be easily the size of a small car, and winding it would either take massive mechanical reduction or massive force from the winder.

So let's say you did it. You set up a watch with all the gear reduction in the world to some sort of heat generation device. You wind the watch up and... The full wind of a 2824-2 mainspring will get you an increase of .008°C in 1 mL of water. Extrapolate that to a turkey (Thanksgiving is tomorrow in the US). Say a fairly average 15 1/2 lb turkey, which we'll round to 7 kg for simplicity, is 70% water (ignore the rest for these purposes), and you want to raise the temperature from 20°C to 70°C. You've got 7,000 grams X 50°C / .008°C per wind of the mainspring. If you could wind the spring fast enough to keep it in continuous motion, and it wasn't also powering the clockworks (which would use all the stored energy in addition to slowing its release beyond the point of the turkey's decomposition; assuming a 36 hour wind down time for the watch, and all of the energy goes to heat generation instead of clockworks, that's 103,561,644 years), and could release the energy of the spring extremely quickly and without any internal friction, you'd have to wind the mainspring 43,750,000 times to cook your turkey. More googling says to expect 13 minutes per pound of turkey, so you'd be winding your spring 3,365,385 times per minute, or 56,090 times per second. A mainspring barrel typically holds something like 5 full revolutions (I'm picturing a Maltese cross whatever it's called limiting device), so you're looking at 16,826,923 RPM just on the winding side. Double that since you ALSO have to unwind to release the energy... Never mind that the spring would explode, I honestly can't think of anything that's running 34 million RPM for any length of time...

In summary, it's POSSIBLE, just not practical, and probably not feasible.

Edited November 27, 2024 by spectre6000

[Stovemaker]

Thank you Spectre6000, for all your help and your work.

After doing some (more) googling  myself its now clear to me that  even a very small space heater would be consuming 0.5 kWh.

The power density of even the most advanced springs lies in the order of  8 kJ/kg (gravitic energy density) meaning a weigth of 10 kg spring would harbor about 80 kJ  = 0.02 kWh.

In conclusion, for building an off-grid space heater i'll really need a more energy-dense power source than springs.

Thank you again for setting me straight on this!

[JohnR725]

30 minutes ago, Stovemaker said:

he power density of even the most advanced springs lies in the order of  8 kJ/kg (gravitic energy density) meaning a weigth of 10 kg spring would harbor about 80 kJ  = 0.02 kWh.

I'm really curious about how much power the stoves you make use? Plus I've never met a stove maker can we get some pictures?

32 minutes ago, Stovemaker said:

i'll really need a more energy-dense power source than springs.

oh and I think you're forgetting there are clocks that use falling weight. We just need a big enough weight with enough elevation and the you probably power anything what you think?

[Stovemaker]

Alas, no, it doesnt work. Poor energy Density again. If i had a 100 kg weight that i could lower 10 meters ( and try to install that in an individual home) the potential energy would be E = mgh, so 10 kg *9.8 m/ s2  *10 meters = 9.8 kJ , which is about 2,7 Wh. In comparison, a single AA battery stores about 2 Wh. This sort of thing works but only on a super large scale, think of towering structures somewhere in a desert. There are projects that use gravity to power a light, but that really requires a lot less energy than warming a room .

Aaaand stovemaker is just my username. Im trying to make an off grid stove \ warming device, havent managed it yet.

[rjenkinsgb]

On 11/28/2024 at 12:09 PM, Stovemaker said:

Im trying to make an off grid stove \ warming device, havent managed it yet.

The most efficient way of getting heat to a place is a heat pump - you can get around 3x the output, compared to direct electric heating.

You obviously need something to extract heat from, that will not cool too much, to maintain efficiency. Such as an old well or deep bore hole or just moderately deep buried pipes can be used for the evaporator side of the system.

[JohnR725]

48 minutes ago, rjenkinsgb said:

The most efficient way of getting heat to a place is a heat pump - you can get around 3x the output, compared to direct electric heating.

outstanding as we now have a viable solution for a clock-based stove either weight driven our spring driven. Although weight driven would be much much better for a whole variety of reasons.