Gravity powered lamp problem

I was very interested to read about this gravity powered lamp…

The designer suggests that it requires better LEDs than are currently available but unfortunately I calculate that it will never be possible to make one…

The maximium theoretical efficiency of any light source is 100% which equates to 683 Lumens/W. Even if we achieved that the lamp would still weigh 1.4 tons.

They say it produces 800L for four hours. Lets say the LED is 100% efficient at 683 Lumens/W so that 800L for fours hours needs 1.17W for 4 hours.

So energy required = 1.17 x 4 x 60 x 60 = 16848 Joules

Energy stored energy in the weight is…

PE = mgh

m = mass in Kg
h = 1.2 meters (four foot)
g = 9.8

so m= 16848/(9.8 x 1.2) = 1432 Kg

1.4 Tons.

Just shows how weak the force of gravity is compared to electricity.

Thanks for pointing that out CWaters. I think you are right.

Why didn’t anyone catch this before? I wonder if the designer showed any hard data in his entry. Oh well.

Yeah, but we can make it 40 ft tall, then it only needs to be 143 kg.

The fact that this idea has gotten so much swooning press is embarrassing. Most people have zero critical thinking skills for anything involving physics or math. I can forgive the judges of the “Greener Gadgets” competition (whoever they are) for not being able to do math, but when something called “Science Daily” can’t do a basic high school level calculation, that’s just pathetic.

perfection, I have a “son” …turthfully it amazed me how much press this bit of unobtainium got.

As a fellow VT alum whos worked with Clay (the designer) while I was still at tech I figured I’d post this - since it was omitted from most of the press releases:

From: http://www.vtnews.vt.edu/story.php?relyear=2008&itemno=111

While many people want to know when the lamp will be available, many others point out that it won’t actually work.

The criticism is that a great deal of weight –- tons – would be required and current LEDs are not sufficiently efficient.

Designer Clay Moulton acknowledges that the current state of the art isn’t sufficient to actually build the lamp. The news release should have said: “based on future developments in LED technology."

Moulton said: “I was told it was not possible given current LED’s, but given the rapid pace of innovation in low powered lighting, it would be a conceptual challenge. The mechanism itself is the novelty. I hope everyone understands that this criticism and even failure is all part of a process, and that my job as a designer is to take this feedback and work on."

The award was for a conceptual design project based on future technology, and the lamp was one of many futuristic designs recognized at the Greener Gadgets Conference.

And while it may not have been presented in the concept, I think there are also additional ways of looking at using a mechanism like this in combination with other technologies like solar power, rechargable batteries, etc. Perhaps it’s the kind of thing that you turn over when you go to work in the morning, and the energy is transferred into charging the batteries rather than powering the LED’s in real time.

It’s a reminder every day of having to deal with engineers who will give you a million reasons why something won’t work rather then searching for the one reason that it will. :unamused:

Cyberdemon,

Designer Clay Moulton acknowledges that the current state of the art isn’t sufficient to actually build the lamp. The news release should have said: “based on future developments in LED technology."

That’s like saying all we need is a perpetual motion machine…(and I’m not exagerating)…

The point is that no LED could ever be more than 100% efficient. A 100% efficient LED would turn ALL the electricity into light. Even if you could make such a device in the future the lamp would still weigh 1.4 Tons. If anyone ever made an LED that was more than 100% efficient they would win a nobel prize as all the worlds energy problems would be solved.

It’s a reminder every day of having to deal with engineers who will give you a million reasons why something won’t work rather then searching for the one reason that it will

I dissagree. You can’t blame engineers for this. This problem is down to the Physicists…

Now this post is reminding me of one of our crit reviews in university. I had pulled out an old article about transmitting energy via microwaves and talked to some fellow students about it. We had a review a few weeks later of small home appliance designs. One student had a device with no cord attached and someone asked him about it. Quickly, he responded it didn’t need one because it would receive the energy in microwaves from a special counter. ha! Seeing as sending energy in microwaves is inefficient when it is highly focused, it’s unrealistic to be beaming it around a kitchen all day.

I like Scott Bennett’s idea. Just to be a devil’s advocate, since the standard ceiling is 8’, a 40’ tall lamp would have a limited market. Also, I did some calculating of my own. A lead weight of 143 kg would be 12600 cm^3. At that size, the designer would have to modify his fixture a lot!

Hey here it is in a nut shell PONY THE CASH…yup thats right put up your own $$$$ and show “us” that it can be done. The rubber hits the road HARD when you put up some unobtainium design on paper (photons are even cheeper) but making that proto work…from your own cash makes you less stary eyed.

You’re right…I suppose it would take more energy to build that big of a device anyways then it would to just put together a mini LED fixture that ran off rechargable triple A’s.

Oh well, hopeless optimism is what keeps the 99% of my pessimism from taking over. :smiley:

Now heres one for the engineering minded: If you connected a small water wheel inside some kind of sealed chamber inline with your home water pipes - couldn’t the water pressure from taking a shower or flushing a toilet be used to generate electricity to say charge a set of batteries? Hydro electric on a small scale? Or would you need to fill the atlantic ocean to light up an LED?

funny you should mention flushing a toilet to generate electricity, I was at a trade show recently talking to a japanese company that makes autoflushing toilets, then use a tiny turbine in the pipe to charge the battery that powers the motion sensor and mechanism to flush the toilet.

Throwing this at the feet of the traditional designer/engineer conflict is a bit rich. The problem here is a lack of intuitive understanding of force and effort. Like it or not, that is part of your job as a designer. Really, it’s the kind of thing all of us should have to know before graduating high school.

First principles: this isn’t a gravity powered lamp, it’s human powered. How much energy do you have to burn to lift a 20lb weight 4ft? Does it ever make you feel like you need a rest, or some food? The energy involved in that transaction is enough to break your toe, but it’s not enough to do much else.

Pointing out the poor beam pattern given off by an LED and its unsuitability for general lighting is an “engineer complaint.” But this is basic, basic stuff.

Exploiting the water pressure in plumbing systems is done fairly frequently. That’s where those pressure assisted 1.6 gal toilets get their pressure.

There’s always a bill to pay though. If you want to tap the water pressure in your shower to generate electricity, you’re going to have to be ok with taking a dribbling, low pressure shower. And of course you’d have to weigh the cost of retrofitting your pipes with an expensive miniature turbine generator against the very low cost of just plugging a charger into the wall socket. But that’s the engineer in me talking.

Scott, chances are he/she/we probably would have know that in Highschool, but after not doing it all through college, and not really needing it on the job, (how inappropriate would it be for a designer to spend his day doing calculations? about as inappropriate as an engineer taking the afternoon to create a beautiful marker rendering) why would you expect him to know now?

Any of us could go pick up a textbook and relearn in a matter of hours, how to do these calculations, but thats not what this guy was being paid to do. I may be missing an underlying arguement here, but why are we up in arms as if this is the first time a non-functioning/non-feasable idea has done well in a contest. A contest that asked for nothing more than three jpgs as an entry. Not to say that we should all just run out and spec perpetual motion machines built into all of our powered designs but really, it was a neat idea. I’m even reminded of a grandfather clock, and what I got from this was how it would be neat to figure a way to power a light using the same idea as the clock, something to think about.

Perhaps thats what got me a bit worked up in the first place. I think this competition got much more publicity through the blogosphere then many others. I’m reminded of a design competition two of my good friends from school entered where their entry (a well styled, environmentally friendly, readily producable product) lost to what essentially equated to a batman belt designed by an engineer, but with zero plausability.

I think that for anyone whos ever been a judge of any kind of student/public competition you’d see that it’s usually the wacky completely unfeasable ideas that stand out over what might be smartly thought out, well designed solutions.

(how inappropriate would it be for a designer to spend his day doing calculations?

Whoa. I do calculations every so often. At least 25% of projects I’ve worked on have a heavy mechanical or electrical functional aspect that has to be verified. Sometimes, I also calculate insertion forces or do trig to determine dimensions around draft angles. I’ve always been paid for these calculations, in fact, I would have been fired had I not!

It also reminds me of a designer I met that was one of the early pioneers of injection molded designer housewares. He told me everything in plastic designs comes down to trigonometry.

As for the design, in spite of the fact the concept is entirely worthless from a functional standpoint, I applaud the designer for thinking outside the box. He came up with an eloquent design both functionally and aesthetically. Bravo. For me, that is a the first level of design accomplishment (the easy one). The next level is functionality.

If I had done the project, I hope that I would have done the calculations and realized that gravity wouldn’t power my design. I probably would have looked at other ways of storing human power (as Scott pointed out) to later use in lighting. However, those techniques probably would have been bulky and failed to win this prize or any other.

That’s the unfortunate bit about these prizes, dreamers are rewarded, doers are forgotten.

Last week I saw another crazy project. It was to give an electrical charged layer (maybe paint, I can’t remember) to cars. That way the cars opposite charges would repel each other preventing accidents. This was one of the finalists at the Michelin auto design award at the Detroit car show.

Now that I think of it, that’s the disappointment. No wonder so many business people think designers are a waste of money. Our most publicly visible face is of fundamentally flawed projects. Sad really…

Quote:
(how inappropriate would it be for a designer to spend his day doing calculations?


Whoa. I do calculations every so often. At least 25% of projects I’ve worked on have a heavy mechanical or electrical functional aspect that has to be verified. Sometimes, I also calculate insertion forces or do trig to determine dimensions around draft angles. I’ve always been paid for these calculations, in fact, I would have been fired had I not!

I was commenting on the fact that we should all know how to do these calculations, and not whether or not we ought to be doing them. It is always everyones responsibility to work together towards a common goal, and sometimes that may mean completing tasks that aren’t in your normal scope of work.

I didn’t think insinuating we weren’t capable of calculation was a fair accusation. An intelligent person is not intellegent because of what he knows, but of what he knows how to find out.

Personally I loved the design but the competition was for “Greener Gadgets” not “Design a sexy lamp”. Did the organisers check if the entries really were green or was greener just put in the title because it’s trendy?

There’s plenty of previously-learned stuff I’ve forgotten (most of it, in fact). I’m not asking that he do calculus here. But step 2 for me after coming up with an idea like this would be to check if it was even remotely possible. After coming up with the 1400kg number I would have stopped, discarded my entry form, and gone on to something else. I know there are people who disagree, but I don’t see the point in impossible concepts. But like you say, even this concept stimulates thought, and maybe that is worth enough to give it a prize.

This impractical idea, for whatever reason, is getting more press than most, probably because it is (or appears to be) particularly elegant. I notice the spin now (check today’s post on Inhabitat) is that this could be feasible “with just a little more LED development work”, which of course was swiftly rebutted in the first comment (not by me, BTW).

My complaint wasn’t so much with the design (which despite the glaring fact it can’t work, is rather clever), but with the general public’s (and even the science press’s) utter lack of understanding of basic physical concepts. Most people couldn’t tell you whether this would work even if you gave them the formula for potential energy and even filled in all the variables for them too.

Scott,

If he had of said that it was based on “future developments in lighting technologies” rather than “future LED technologies” would this have been more acceptable?

That is a big problem with design contests, You can usually win by taking the most literal translation of the rules and creating a solution without any concern to real world constraints.

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But on the flip side, maybe this is getting so much press because people are starting to wish we could do something like that.