supercharged lemon

Nice idea. But does wasting food count as "green"? Would it work as well if you used sea water, or water full of potentially current-carrying pollutants (then you could call it a lamp run on pollution!).

A lemon can turn into soil and another lemon can grow from it. Pollutants can't, and neither can a battery. This isn't the next oil, as it is not efficient, but it is an interesting and feel good way to run a small clock for a month.

Just a thought about "green". Using something that reproduces like a plant in the process of acquiring energy sounds very "green". No footprint, yada yada. For this contest in general I would imagine that all reoccurring fruit usage is very fair game considering that plants continues to produce while the fruit decays. The only downside I would see is the good one could do with food for the needy, although I don't imagine starving people would prefer a box of lemons.

Something to add to the thought, though, is the energy required to process the lemon - pick, pack, transport. If it came from your own grove, I'm sure it would be C-neutral, but all UK lemons come from overseas.

use the seeds in the lemon to plant. now that would complete the life cycle.

I grow my own lemons (wow that sounded weird lol)

it really did lol

Hmmm... we could look at it from a different perspective. How is it "wasting" if he is consuming the energy from it? When he is done he can compost it etc ect. If he didn't live near sea water he would have to make his own, would that be "wasting"? Just personal perspective questions.

I was half thinking, without checking the practicality of it, if this could be used to clean water polluted with metallic ions - the polluted water flowing between the electrodes (in place of the lemon), and instead of the LED, a pair of plates downstream of the electrodes, gathering metals by electrolysis.

It would pretty much be a self-powering pollution-clearing device.

metal ions are not pollutants. They are what make the water conduct electricity and without them we can't drink it. The distilled water is abrasive and sucks out things from your body so that it is not distilled. Water always wants to have something in it.

As I am sure you are aware, there is more than one kind of metal. Water containing small traces of calcium will be fine, but high levels of lead, mercury, tin, copper, uranium, iron, in fact just about any metal will always make water toxic.

The issue is that it takes out ALL the ions, making it distilled and therefore undrinkable.

Oh, sorry, I wasn't disputing that DI was not a clever drink - I thought you were saying that water needed plenty of metallic ions to be healthy. (You can drink DI for short periods, although it is utterly tasteless. I was bored before the end of my first glass.)

Would that be like just consuming finely shaved (insert deadly metal of choice)?

No - most toxic metals are toxic as compounds, which is why things like lead have been banned from petrol and paint.

Mercury, though, is toxic as the metal as well (do you know why the Hatter is Mad?)

Well I do know a bit about mercury; one day i'd like to get a radiation suit, fill a silo with mercury and use it as a trampoline. And the Hatter? Has he been playing with thermometers?

That would be fun!

Although half a tonne of mercury isn't going to go down with the local council very well... XD

Hatters used felt, felt was made with mercury, mercury fumes damage the brain.

I guess one does learn something every day!

Actually many elemental metals are toxic. Iron is necessary for humans, by the way.

Iron is necessary, excess iron is dangerous.

How about that dude that ate a plane?

He ate metallic metal (and an awful lot of plastic, card and glass) - it's mainly metal compounds that are the toxic beasties.

Ahh I see, so next time I go for a midnight snack I should definitely check the ingredient list of my Boeing 737.

That would be cool, i would like to see it done, but wouldn't that be a machine that ran for infinite, and my science teacher claims we cannont make something like that, so i would like to see it done! =D

This isn't a perpetual motion device. It could run indefinately as long as a xcontinuos source of poluted water was there to power it. It would of course need cleaning from time to time do to build up of said pollutants. And maintainance for basic wear or corrosion. But the device has an 'outside' power source in the water.

It's not over-unity (I think) - it would be using the chemical energy of the pollutants themselves, refreshed by the kinetic energy of the flowing water.

You wouldn't be able to clean it thoroughly really.. You'd hit an equilibrium where metal ions formed neutral compounds in solution.. To prevent that kind of action membranes need to be engineered to particular expected anions and cations.. I wish it was that easy though.. If it was I could get pure sodium and potassium metal from simple aqueous electrolysis..

If I'm right (and I may not be), it would extract the metals (often the most toxic part of a pollutant) as solids on the electrodes.

Oh...

But the other electrode will simultaneously corrode, replacing the polluting metal with a different polluting metal.

Bum - that's a dead idea.

It was worth a try. Perhaps a physical filter could be placed around the corroding electrode. Fine enough to allow water to pass, but not permit contamination back into the main body of water. Would provide for a bit more cleaning upkeep, but it might work. assuming the your new contaminant are larger than water.

yeah that would be cool

Well, it doubles as a citrus air freshener, so that should count for something.

This is a clever idea! It would have fit in the Mash-Up contest, too.

Ah but the food was made using Co2 removing methods so it's fairly green either way, that and I'm pretty sure that you could use a different media such as polluted water made from condensing the suphuric acid etc. made in coal power stations in water, I think that would work, I can't quite remember how it works due to my own poison... Masybe tomorrow, in fact make that the next day...

I'd like to know whether using a lemon is more or less green than disposable alkaline batteries- someone should do a complete environmental audit (energy used, CO2 production, transportation, waste product disposal etc), and I think that would make a great science fair/research project. If I had kids, I'd set them straight on it :) Personally I'm not sure the lemon is the major materials expense- surely refining the copper/zinc counts as well, as they are consumed in using the battery, and copper prices are at an all-time high. Another random tangent- this is a fairly well known experiment, but are there any vaguely practical (read- can power this sort of project, not necessarily laptops or a Prius) rechargeable batteries that can be made out of household materials? I'd imagine trying to charge this would just make your room smell of burnt lemon...

Yes, but you can continue to reuse the copper and the zinc. All you replace is the lemon. Even with transportation, lemons grow on trees. That turns CO2 into O2, which is good. Alkaline batteries have pollutants and harmful materials in them while lemons make good compost to grow more lemons.

Hmm...Burnt lemon...I wonder what that would smell like (Lights the grill with a lemon in one hand. Mwahahaha.)

If you had something that did not use a lot of power you would would want to use lemons. the opposite if you were using something that used a lot of power.

Hmm worth a go, a car battery works on a similar priniciple.. then again household products could be used and reacted ad infinitum to make the base materials...

great instructable s8, i built this lemon Battery with a slightly different circuit it worked well. lit up my digital thermometer & used as a night light. Thumbs up mate!

demon lemons strike again O_o i see in the last picture they are pretty dead by the time the energy is used up eh?

What was the purpose of the transistor?

a joule thief works by making thousands flashes perseccond, thus the need for a swithc of somesort,in this case it it the transistor, but a solid state realy might work too

oh so the light flickers? how fast 10hz? or what?

it flickers faster than AC current, and that is 60Hz

so about 100 something hertz? wow you would probably need a high-speed camera to capture that flickering

its probably way too fast for all but the highest end cameras

no...ive seen cameras that record at up to 5000 frames per second you would need a 60 FPS camera to record it according to s8 since he says that they flicker at 40-50 hertz that 40-50 times per second ...right?