Half a croissant, on a plate, with a sign in front of it saying '50c'
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Living Lemon Battery Tree

Lazy tree! Get to work!
  [vote for,

Bakers have bandied about various schemes by which trees could be used to produce energy. Harnesses could capture the kinetic energy of windblown branches or creeping roots, or the trees could be burned in power plants. But consider the ornamental citrus tree. No-one eats the fruit, which falls hopefully to the ground to molder and be raked up by landscapers. Could these unloved fruits be used to generate power?

The idea is based on the lemon battery (linked). The lemon provides electrolyte. On making a lemon, the tree must use energy to make the fruit sour against a gradient. I wonder if a lemon still on the tree could generate current longer than a picked lemon, as the tree will be still be working to replenish ions depleted from the lemon.

The science project: a comparison as regards power generated and longetivity of live lemon vs picked lemon batteries.

The halfbaked scheme: all lemons on a tree are wired together (see link) and generate power for a light at the top of the tree. Alternatively the power could be used to run a small speaker, which would be more impressive during the day. The speaker might play Bert singing "La la la la .... lemon.". Over and over.

bungston, Apr 20 2009

Lemon battery http://www.hilaroad.../lemon_battery.html
Just so. A consideration: toxicity from metal ions might damage the lemon and reduce longetivity of the live lemon battery. It may be that chosen metals generate less power initially, but are easier on the live lemon and so permit greater longetivity. [bungston, Apr 20 2009]

La la la la... lemon. http://www.youtube....VkA&feature=related
Be true to yourself, Bert! [bungston, Apr 20 2009]


       The lemon might provide the electrolyte, but it's the electrodes which are stuck into the lemon that are providing the ions which are providing the power. So as long as the electrodes are good, voltage is present -- it doesn't matter if the lemon is live or dead.   

       The idea might work, but not any better than if one picked the lemons, juiced them, and used the juice as battery electrolyte.   

       Of course, if you're going to pick and juice the lemons, you might as well make lemonade.
goldbb, Apr 20 2009

       Two things about this. Limes are more acidic than lemons, so they'd work better i think, and you might have to be careful about the choice of electrodes or you'd kill the tree. Do differences in electronegativity determine the voltage?
nineteenthly, Apr 20 2009

       19: that lemon battery link links to a table showing electrical potential of various metals, so I think yes.   

       But re acidity I am not sure about that. I think any electrolytic solution would work; even pH=7. But I was under the impression that running a battery depleted the electrolyte. It is very possible I am very ignant.
bungston, Apr 20 2009

       Acids can be thought of as "proton"/"hydrogen ion" donors. So yes, limes are better. Given the lower pH.   

       //Do differences in electronegativity determine the voltage?// No, well sort of. It is an issue of potential, and resistance. If you have a keen electron receptor on one side (such as a good proton donor(acid)) and a good electron donor on the other (like earth) you could get a good current (I). But that depends less on the potential (V), and more on the "internal resistance" (R) of the medium, after all, V=IR (Ohm's Law). I use earth because it is both a good electron donor and electron receiver. Therefore the only variable is the conduit. Lemons and limes are not the most efficient.
4whom, Apr 20 2009

       However, given that lemons, and limes, produce this proton donation for mere sunlight it should be possible to construct a carbon neutral "potential" across this field. And an even greater potential across evaporated salts, for eg.   

       Hydroxides just love giving away their extra electrons.   

       Unfortunately that old bug-bear of science rears its ugly head. The internal resistance of these mechanisms just can't be swept under the carpet, no matter how we charged it...
4whom, Apr 20 2009

       Cathone? Anode?
WcW, Apr 21 2009

       Lemon tree very pretty and the lemon flower is sweet
but the fruit of the poor lemon is impossible to eat.

       Peter Paul and Mary   

xenzag, Apr 21 2009

       It obviously is this time of year. Already.
loonquawl, Apr 21 2009

       When I was a young boy, every day I would stand at the Bet Dagan junction waiting for my bus home. Far in the middle of the bare intersection was a single orange tree, with great looking fruit. But nobody ever had dared to leave the station for fear of missing their bus. One time I decided I couldn't stand it. The fruit just looked too good. There were some other people at the station and I decided I would go and get the fruit and distribute it to everyone waiting.   

       A soldier took on with a smile. Then "TFU!!" he spit it out "Its Hushhash!". "What's Hushash?" I asked. "Its the fruit of the original orange tree without being "grafted" with another tree, so its inedible".   

       I remember American tourists in Rehovot, "the city of citrus" asking me if the oranges on the main road (Herzl Rd.) were free for everyone. I told them they were "Hushhash" not treated, so inedible. They decided to try, despite my warnings. In Hebrew oranges are called "Golden Apples". Not everything that glitters is gold.
pashute, Sep 02 2011

       Good story [pashute].
normzone, Sep 02 2011


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