|
| Author |
Message |
paulz
Member
|
# Posted: 6 Jan 2019 06:35pm
Reply
Ate too much before bed last night and got the wild idea that I could hoist a big weight up a tall tree, tie the end of the rope to an alternator pulley (or something like that) and generate power as the weight dropped.
Sure enough, you can buy a gravity lamp. I just need to ramp up the scale. 
https://www.amazon.com/GravityLight-System-GL02-Portable-Powered/dp/B01M7SM0KE/ref=as c_df_B01M7SM0KE/?tag=smacab-20&linkCode=df0&hvadid=242033512944&hvpos=1o1&hvnetw=g&hv rand=17867539644548034449&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy =1014073&hvtargid=pla-350304772278&psc=1
|
|
RichInTheUSA
Member
|
# Posted: 6 Jan 2019 07:40pm
Reply
When you say "up the scale"... are you referring to increasing the height, so that the length of time the light stays on is longer? Or are you referring to increasing the wattage for a brighter light?
|
|
Atlincabin
Member
|
# Posted: 6 Jan 2019 07:40pm
Reply
There have been folks experimenting with this sort of energy storage for a number of years. One large-scale effort involved using off-peak power to pull a loaded freight train uphill and letting it coast (slowly) back downhill. All sorts of other schemes if you look around the internet. Most of them suffer from 1) too much loss of power during the process and 2) they don't really store enough energy to be worthwhile at any sort of cost scale.
|
|
darz5150
Member
|
# Posted: 6 Jan 2019 08:19pm
Reply
Did some un scientific calculations based on some product reviews. One person said with an 8 foot ceiling, he could get around 15 minutes run time.
So if you extended the ballast chain, and hung it in a 300 foot tall tree. You could possibly get a little over 9.3 hours of run time that produces around 15 lumens of light that is equal to around 1.176 candles.
Not sure if I am correct in my calculations!?
Another scenario: If you buy 2 50 count packs of tea candles from the dollar tree for $2 bucks. Each would burn about 6 hours,...therefore producing 600 candle hours of light.
|
|
paulz
Member
|
# Posted: 6 Jan 2019 08:31pm
Reply
I was figuring to charge my batteries with it. I could do about 150' height. Weight would depend on what was used to raise it. My useless dog maybe.
|
|
darz5150
Member
|
# Posted: 6 Jan 2019 08:44pm
Reply
@paulz. ðŸ‘ðŸ‘ðŸ‘😂
|
|
Wilbour
Member
|
# Posted: 6 Jan 2019 08:49pm
Reply
Saw this marketed as a lamp for 3rd world countries. Kids could do homework without the use of Kerosene.
|
|
ICC
Member
|
# Posted: 6 Jan 2019 11:24pm
Reply
Quoting: paulz I was figuring to charge my batteries with it.
Off-grid storage batteries? I don't think so. 15 lumens from an LED takes very little energy. The charge into a typical small scale off-gris system would be hardly noticable.
To recharge AA penlight flashlight batteries, maybe, but at what cost of materials? As wilour pointed out, this idea makes perfect sense for someone in a third world country if doing so means they don't need to burn kerosene. There are also small solar charged lights that are promoted for that purpose. Much more healthy for the people to avoid kerosene lamps.
|
|
|
ICC
Member
|
# Posted: 6 Jan 2019 11:25pm - Edited by: ICC
Reply
https://www.deciwatt.global/gravitylight/
copied from the spec page
Nominal Voltage* 2.7 V DC
Max current* 0.031 A
Max electrical power* 0.085 W
I would hate to try and read if all I had was a 15 lumen light.
For reference, an old 25 watt incandescent bulb has approx 200 to 300 lumens. Those seem pretty dim to me. Now chop that to 15 lumens------
Those 7 watt night light incandescent bulbs put out 40 to 50 lumens.
|
|
paulz
Member
|
# Posted: 6 Jan 2019 11:57pm - Edited by: paulz
Reply
Quoting: ICC Off-grid storage batteries? I don't think so. 15 lumens from an LED takes very little energy. The charge into a typical small scale off-gris system would be hardly noticable.
You're comparing the output of a small weight dropped a few feet to perhaps a couple hundred pounds dropped 150 feet. It may indeed be a silly idea but not as bad as you say.
|
|
darz5150
Member
|
# Posted: 7 Jan 2019 12:59am
Reply
Quoting: paulz It may indeed be a silly idea
@paulz. Sometimes silly ideas turn out to be amazing my friend.
https://youtu.be/qybUFnY7Y8w
|
|
Ontario lakeside
Member
|
# Posted: 7 Jan 2019 01:07am
Reply
this has been done for years, a pendulum in a clock operates using energy stored as a weight falling. in the UK they have a hydro electric system that uses pumps to store water in a lake on a hill and then when needed let it drop into a turbine to generate power. The problem with all these systems is that it takes more energy to lift the weight than can be recovered. If you use wind and solar to lift your wight you can recover the energy at night and when there is no wind.
|
|
Ontario lakeside
Member
|
# Posted: 7 Jan 2019 01:08am
Reply
A link to the system in the UK
https://www.youtube.com/watch?v=McByJeX2evM
|
|
paulz
Member
|
# Posted: 7 Jan 2019 02:06am
Reply
Great videos. If what I could come up with proved adequate for making some usable power, and I'm not smart nor interested enough at this point to calculate if it would, I wouldn't mind if it took running a gas engine for a few minutes to winch the weight up if it would then provide some hours of quiet, trouble free power generation. Right now my only source of battery charging at the cabin is running generators as I have no sun for solar. I use deep cycle batteries in my truck and charge them back at home or when I drive.
|
|
FishHog
Member
|
# Posted: 7 Jan 2019 09:34am
Reply
The problem is there is no free energy. You will get losses using your generator to hoist the weight. It would be more energy efficient to use that generator time to directly charge your batteries.
|
|
ICC
Member
|
# Posted: 7 Jan 2019 09:50am
Reply
Quoting: FishHog The problem is there is no free energy. You will get losses using your generator to hoist the weight. It would be more energy efficient to use that generator time to directly charge your batteries.
no free lunch
|
|
ICC
Member
|
# Posted: 7 Jan 2019 09:59am
Reply
A gravity system to produce electricity might make sense when the energy used to elevate the weight, water, whatever would otherwise be wasted or comes from the wind or sun. If you need to burn fossil fuel in an engine to generate electricity I don't see any advantage. As was said it would be more efficient to generate electricity with the engine. Every system has waste from friction and other inefficiencies.
|
|
paulz
Member
|
# Posted: 7 Jan 2019 10:00am
Reply
I use my generator frequently, daily, to run power tools, my only source of AC. Only recently did I realize I should have a battery charger connected to it at these times since it has plenty of capacity and I generally leave it running for periods between running the saws etc.. It could also power an electric motor to hoist the weight using this otherwise wasted energy.
But that's really a side issue. What I like about the gravity idea is it could 'run' at night, while I'm not there, or when I just plain don't feel like listening to the generator. If that means wasting a bit of energy so be it.
Again this was just a wild idea. No idea how much power it could actually produce, or for how long, or what it would take to hoist the weight. But it is an interesting thought and I appreciate the comments.
|
|
Fanman
Member
|
# Posted: 7 Jan 2019 01:06pm
Reply
A one pound weight dropping at 1 ft/min would produce 0.023 watts, scale it from there. Conversely, to produce one watt you'd need 43 lbs dropping 1 ft/min, or 1 lb dropping 43 ft/min.
|
|
paulz
Member
|
# Posted: 7 Jan 2019 01:17pm
Reply
Well that doesn't sound too beneficial. Thanks!
|
|
|
