Is a clockwork powered house possible?

Is it possible to make a giant clockwork device with a million gears in it that would spin all day on just a few minutes of initial winding?

Like if you could just wind it up for say 10 minutes.

And then it would very slowly wind down, but the motion would turn a billion gears that would result in a very rapid spinning at the end of the gear chain, one that could drive a standard power generator (magnet/coil) enough to power your entire house?

For instance, you wind it up 10 minutes, then it winds down for 24 hours, spinning a shaft 20,000 RPM the whole time. Maybe the wheel you wind up would be 15 feet tall and then it would drive a ton of gears until the final gear would be really small and spin really fast all day long.

Can it be done?

No reason why it couldn't be done - the spring acts as an energy storage device. There will be a variety of significant losses so you'd need to put in somewhat more energy than you recover just like any other other storage system.

A mathematical look at the system:
Let's assume you want to supply an average 2kW from the generator at the output and can only wind it up once per day in a period of 10 minutes. Let's also assume you get a spectacular overall efficiency from winding to recovery of the energy of 80%.

2kW x 24hrs = 48kW.h
with 80% efficiency the input required is 48 / 0.8 = 60kW.h
To input 60kW.h in 10 minutes or 1/6 hr:
Winding power required is 60 x 6 = 360kW or 360/0.746 = 482.5HP!!!

A turbocharged 6 litre V8 would do the job nicely

I'd be concerned about the consequences of that spring breaking too :O

Oh.

Now that is a great idea. Have an internal combustion engine burn up a little gas to wind a massive mechanism.

Nice.

And that math... really nice. Thank you.


[edit on 26-8-2009 by THX-1138]

I think you need to start looking in the direction of Flywheel energy storage. So rather than storing Solar power in batteries you use a large fly wheel e.g I think about 10 tons the wheel would weigh.

Flywheel energy storage

Short answer is yes. The thing is that the gear you crank would require one heck of an arm to only crank for 10 minutes. As in Superman would ask you for an easier task like bench pressing 747's for a couple of hours.

You *could* reduce that effort by cranking for much. much longer, however finding that comfortable trade off point would be the real trick.

Honestly, some backup generators in hospitals use the connected electricity to spin a large and heavy flywheel at around 20K RPMs. When the power is cut, a small drive wheel engages to provide about 5 minutes of power until the automatic diesel generators kick in and get up to speed and take over.

Now it is not a perfect system. Power can be restored for a short time and go out again. Should the diesel cut out and the flywheel has not reset to full speed, there will be a power outage until the diesel ramps back up again.

So, yes. the clockwork generator would work. You just better hope that nothing happens to Lois Lane in the morning, before the cranking time.

Found this in an old University Engineering book at home

The energy storage capability of flywheels approaches 130 watt-hours per kilogram (Wh/kg), with power capabilities of around 500 watts per kilogram (W/kg).

Present capacities range from 2 kWh upward, with capabilities of providing megawatts of power for a few minutes.

I only did that to show what the required actual input would be for a real system. There's a good analogy there to solar systems which need to store 24 hours worth of demand with only 6 hours or less of good sunlight per day.

The economical answer in the end is to drasticly reduce demand by using energy efficient building designs (no aircon etc), solar water heating and possibly bottled natural gas for cooking and heating so the only electrical demand you need to supply is lighting and things like pc's, entertainment systems and the like. Let's hope LED lighting gets down to a realistic price in the near future too.

Theoretically it would be possible, but since you, the 'cranker', are not going to be able to put a lot of energy into the clockwork system in 10 minutes, it wouldn't be very useful. However much energy you put in is how much you get out, and 10 minutes of cranking won't do very much. It's a similar (but cooler!) idea to hooking up a bicycle to an electric generator and pedaling for 10 minutes.

You could make the clockwork device, by designing it right, spin all day with just 10 minutes of winding, exactly the same way oldschool watches work all day after just a few seconds of winding. The only catch is, again, you didn't put very much energy in during those 10 minutes, and discharging it out over 24 hours is going to result in a very low power output.

If you wanted this to be practical, you'd need a better way to get energy into the clockwork device. Maybe something based on wind power? Have the wind blow against a windmill thing and turn the clockwork device instead of you doing it yourself.

Possible? Yes, sure. There is little that is not possible in physics.

Practical? Not at all.

Pilgrum did a bang-up job of showing the calculations (although I would say 60% efficiency would be a safer bet than 80%). The power needed to crank a spring for only ten minutes a day, or even a couple hours a day, would be massive to power a household with the current power requirements. Not to mention the cost of those 'billions' of gears. My best supplier sells small clockwork nylon gears for anything from $2 to $20 each, depending on the gear. Metal gears are higher, and would definitely be required. As a matter of fact, under the power considerations for an entire household's daily usage, you're going to have to get some bigger gears, which come with a much bigger price tag (a recent project priced a single worm gear set at about $150.00).

Now let's talk about the spring. We're talking about a spring that would make the suspension under your car look like a toy! Think about taking a steel I-beam (wideflange for the purists out there) maybe 12"-14" deep and bending it almost double to store the energy. Now think about what happens if it breaks.

You could use that monster flywheel, but how exactly are you going to get a 10-ton flywheel mounted outside your house? Not to mention the safety hazards if it developed stress cracks and fractured...

So you are going to have to pay more for that clockwork mechanism than it would cost for you to power your home as is right now for the next 100 years. You will have to use a turbo-charged V8 at high RPM to wind it for those ten minutes (and pay the associated fuel costs for that as well). In the end it would be easier and cheaper to use that V8 to turn a few dozen alternators and charge batteries directly.

Keep thinking, but this one is busted.

TheRedneck

Powering your entire house is a waste of energy and impractical - especially at only 10 minutes of 'cranking' per day - though, I realize that '10 minutes' was probably an arbitrary figure the asker threw out there. And, as the other posters stated, the idea should be to design your house to be more efficient in regard to heating and cooling... (AND lighting, btw)...

Why not consider a smaller system for each room and/or each major appliance? Baby steps. I think 30 seconds of cranking/winding is worth a couple pieces of toast, yes? And 15 minutes a day to keep the refrigerator going? Seems worth it to me - hell you could make it poetic and attach a stationary bicycle or stairmaster to the side of the refrigerator and set it to REQUIRE you to 'exercise' 30 minutes per day to keep the food cold! Talk about buns of steel! Want to be a couch potato and veg out with the boob tube? It'll cost ya 5 minutes on the treadmill per hour showtime! etc. etc. etc.

- LaBello