Electronics → GravityLight: lighting for developing countries.

The project
»www.indiegogo.com/projec ··· s/282006

Great project, I have a problem with the name. It gives you the feeling of something for nothing when, in fact, it's work done by the user.

Still a good job by the developers.

What a clever idea - a "windup clock engine" for the 21th century. Human are pretty good at energy storage, and LEDs are efficient. Assuming people are not starving this is a great way to provide a small amount of electricity. Not just for lighting but enough to charge a cell phone or radio so folks are able to connect to the wider world.

Agree with the developer's assessment of small scale solar. Until there is a more reliable method of storage it does not really solve the problem. Even in developed countries grid tie systems beat out battery backup unless you really want to live off the grid.

They wanted to raise $55K and so far they are up to $325k.

What an inspirational way to start off the new year.

/tom

Exactly, thanks to LEDs and some clever mechanics. Light for people that have none.

Being goofy as I am, I started thinking about this clock at Thomas Jefferson's home in VA. It has weights that run from the high ceiling of the first floor to the basement. You crank the weights up once a week. (if I remember correctly) I was thinking, I want to try it there.

I think is a very good idea, but I am not sure it will really be that useful. The output of the light is relatively little. The output will probably be about on par with a quality shake flashlight and much less than a crank light and also be less convenient to use. Solar can triumph them all. You have to realize, this has to be hung up high. It will cast a glow to a direction in the room. But you would be hard pressed to do much with that light. Even on the highest output setting.

It's what you are use to and how it replaces it. Did you watch the video?

vimeo.com/53588182

When you have a choice between this and a lamp that runs on petrol (roughly the same light output), or no light at all, I think the choice is pretty clear. Anything solar powered will normally require batteries -- they are expensive and wear out, especially in less than ideal operating conditions.

I definitely watched the video. This is really nothing more than an awesome night light. That's how effective a single lower power LED is. It's hard to do anything by such little light, especially one that will be hung across the room.Maybe, maybe not. This light won't be bright enough to light up a room. It won't be bright enough to read by unless you stand up next to it. Don't be deceived by the video and pictures. This is not a bright light. Kerosene lamps are brighter and more portable. Kerosene can also be used for cooking. Really, the gravity light is an attempt to solve a problem without taking into consideration what is actually required to solve the problem. Simply making a light that costs nothing to run won't solve the problem. It has already been done.

The battery problems of solar lights were solved some time ago through the use of super capacitors. Although the company making the lights appears to have gone bankrupt. There wasn't enough demand for their lights, in part due to the price. NiMH batteries can be purchased for under $1 and last years.

I've always wondered why the bit electric utilities haven't applied similar technology to windmill power. It seems trivial to me to use a water pump to fill a tank or reservoir to capacity when the wind is blowing and then flow it back down thru a generator once the wind stops and you have to go on reserve power.

This HAS to be more efficient and less costly than trying to store power in a conventional battery system.

Likewise why not use a tank of compressed air? Run a compressor with excess energy and fill a tank with compressed air to be released during the doldrums in wind power.

I really don't understand why they're futzing around with expensive, limited lithium batteries these days when these technologies have been around for over 150 years?

In summation, the concept of the gravity battery is NOT a new idea.

This type of storage is often used by utilities.This storage method is also used by utilities as are ultra efficient flywheels spinning in a vacuum.

That is all large scale utility power. These guys have come up with a low cost way to deliver small amounts of electricity at low cost.I think you are missing the point. I agree this is not a new idea, clocks have used same technique for hundreds of years.

What is new is 1) using it to generate electricity, 2) Efficient LED light source. 3) low price point to compete with less environmental health friendly sources of light.

/tom

Nonetheless I am not seeing these technologies applied anywhere to wind power these days. Everywhere I look I am seeing $Billion$ invested into development of better batteries and constant complaints that wind power is not a steady or reliable source of electric power.

The simple application of a gravity battery at every wind turbine station would allow wind to supply the grid with a constant flow or power regardless of any hiccups or glitches in wind speed.

Btw, in case nobody has patented this already, my IP is duly noted and logged and my posts constitute prior art

silbaco ]

I get the feeling you will never be convinced but I throw this out anyway. A 10 YO study, so the LED technology has had 10 years to improve. The kerosene technology, not so much.

quote:

---

Summary and Conclusions

The energy use and light output of kerosene lamps vary widely depending on the type of
lantern used, maintenance of the wick, and the cleanliness of the “globe”. Moreover, our
measurements indicate that light distribution is very uneven in both the horizontal and
vertical planes, i.e. depending on the angle of view. Kerosene-based light is poor for
reading and many other tasks, particularly on horizontal surfaces.

Our estimates of useful illuminance on typical tasks show that the kerosene lamps deliver
between 1 and 6 lux (lumens per square meter), compared to typical western standards of
300 lux for reading. Light output deteriorates considerably from these already inadequate
levels within a few hours of operation (by up to 83% in our tests) as the globe becomes
soiled, requiring frequent cleaning. In contrast, “lumen depreciation” in electric lighting
systems is typically in the single-digit range after years of operation.

A competitive analysis of kerosene lanterns versus conventional electric alternatives
(both grid-based and grid-independent) and emerging white-LED alternatives shows
considerable potential for economic and environmental benefits. When evaluated in
terms of total cost of ownership (fixed and variable), the LED systems emerge as the
most cost-effective solution, with payback times from several months to two years.

---

»evanmills.lbl.gov/pubs/p ··· ting.pdf

That's an interesting read.

I have no doubt that LED light is superior to kerosene. What I doubt is the power source of this light. I can't see this light putting out enough light to be useful. Even with the most efficient LEDs on the market.

I've seen the candle-powered Peltier, which to be honest seems a much better choice. You can get the light of the candle plus the light of the LED and it runs for many hours.

We have a few storm lights around the house. The have no batteries and use LED bulbs.
»www.amazon.com/Shake-Fla ··· 00637LTY

You just shake them and you get light for a few minutes/hours depending onhow long you are willing to shake them.

Then we also have a crank powered emergency radio:
»www.amazon.com/ER-Emerge ··· 007CL02S

A real pain in the ass to use, as it takes a while to build up enough of a charge to power the unit.

The use of a weight to generate the power, is pretty nifty as it frees you up for other things.

I have to do some calculations but maybe hand-cranked pulleys can be used to pull up a much bigger weight (rocks/bricks/water containers) to store much higher potential energy.

Another option could be a small enclosed flywheel assembly which is spun up to very high rpm using hand cranked mechanism. Yet another option is a heavy pendulum on a low friction pivot?

However, the cost of the mechanics of such battery-less systems need to compare well against locally made and recycled lead-acid batteries which are quite cheap.

*** Rural solar is quite feasible for developing countries. The country where I was born has millions of "solar home systems" ... see my old post ( »Re: Solar Training ) for a photo montage of rural female entrepreneurs (often with just grade 5 education) assembling the charge controller PCBs and installing these systems.

Google image search shows many more examples: »www.google.ca/search?q=b ··· &bih=676

»en.wikipedia.org/wiki/Ca ··· ood_Lake

pumped storage generation has been done. Commonly used for peaking needs. water is pumped up at night and then flows out during peak usage in the daytime.

Interesting. It was built in 1928 and it's still in operation today. So why are the utility companies not building more of them today? I live in the province of Ontario where about 90% of our electricity comes from Nuclear Stations and Niagara Falls.and any other smaller hydro generating stations. The remainder comes from oil and gas fired plants and more recently wind turbines and other "green" sources.

»media.cns-snc.ca/ontario ··· ity.html

At any rate, there's a huge political push in this province to switch to greener sources and there's been a scandalous history of mismanagement of our utilities by our government which has left the infrastructure inadequate and overpriced and non profitable for decades for which every resident of this province pays dearly.

It seems that current political will in this part of the world is willing to spare no expense to invest in solar and wind (despite the painful and costly lessons learned by the Germans and the Danes) while engaging in expensive boondoggles like selling surplus power back across the US border at below cost during low demand hours.

At any rate, in my own humble estimation, politicians are too mesmerized by their own rhetoric about windmills and solar and battery research to even consider investing today in 84 year old technology to make the entire process more efficient.

For our politicians it seems to make more sense to install "smart" electric meters to further rape the ratepayers than to invest in a century old technology to store some of that wasted energy for the peak demand hours.

Nonetheless, you cite only one example of this technology. Is it in widespread use across America or was Connecticut the only state with the foresight and political will to implement and maintain such a significant and useful project back in the 20's?? (Note it was built one year before the market crash of 1929)

Has anyone else built any of these anywhere since?

Both the U.S. and Canadian hydroelectric installations in Niagara Falls use reservoir energy storage. Fill at night with water from above the falls, drain during high demand (day) through the generators and it exits below the falls.

As for the general usefulness of reservoir storage, they take up a LOT of space per KWH stored, plus the turnaround efficiency isn't all that great. Plopping a big storage lake in the middle of an area creates its own eco-issues and likely displaces a bunch of people, may require a massive public works project to contour the land properly, etc.

A big reason they do not build more is land, you need the right land or do lots of digging to make the lake. Also it is highly unpopular to displace people. Candlewood flooded a small town, Outside of China you could never relocate a town today just to build a hydro plant because the citizens of the town would tie it up in court for decades. And in the end it would likely cost more than just building a nuke.

I wonder how long these gravity lights are expected to last under daily usage. 20lbs of weight pulling on plastic gears just doesn't sound like a good combination.

Have you done much work with plastic mechanisms?

With only 18-30 minutes of use per lift, I wonder how useful they will be.

I'd imagine pretty useful.. It wouldn't take more than a few seconds to lift the weight back up to its highest point.

~20 min of light from a few seconds lift.. Not the most convenient, I agree, but certainly useful.

potential energy = mass * height * g

let's round off g to 10 m/s2 and use 10 kg (20lbs) lifted to 2m (6ft)
that's only 200 joules stored per lift. If we want 15 minutes run time, max power available for the LED is only about 200mW for almost ideal loss-less scenario. That will be less than 20 lumens which is quite dim.

Since height is limited by ceiling, a lot more weight needs to be lifted to give useful lumens. The generator's permanent magnets could be embedded into a heavy duty molded plastic winch mechanism that could lift 100kg for example.

the gears in my RC helis are plastic and run at MANY 1000s of RPM
as are the gears in some my aircraft servos which hold up to many lbs
i have no issue with the gears being plastic