Fruits that can produce electricity! Researchers recently have concluded that fruits may be used as a renewable source of energy, as in creating electricity. Fruits are known for their very high sugar content. Traditionally, sugar can be converted into ethanol which in turn can be used to power automobiles and other vehicles, making such using renewable energies.
What Fruits & Vegetables Conduct Electricity?
Science Project on Electricity in a Potato
Fruits and vegetables contain important vitamins and minerals human bodies need to survive and maintain themselves properly. However, interestingly, these same fruits and vegetables also contain a large amount of water and, thus, can in some cases conduct electricity well. Other ingredients such as citric acid and ascorbic acid increase the conductivity, and in some cases, the acidic content is high enough to create voltage that can power small electronics.
TL;DR (Too Long; Didn’t Read)
Many fruits and vegetables can conduct electricity and, in some cases, even create an electric current that can power small electronics.
Vegetable Electricity Conductors
Potatoes, onions, and tomatoes conduct electricity quite well. Tomatoes (not vegetables, strictly-speaking ) are good conductors in the vegetable category, as they have the highest acidity level. Scientists have show potatoes work very well as batteries. Acids make ions, charged particles when placed in a solution like, water, which many types of fruits and vegetables contain in abundance.
Fruit Electricity Conductors
Citrus fruits work as excellent conductors due, again, to their high acidity level and the presence of water within them. Some notable examples of good conductors include:
Making a Circuit with Produce
When a fruit or vegetable is connected with electrodes in a circuit, the fruit or vegetable serves as the battery to complete the circuit. Some of them can even power small light bulbs for a time. Some researchers have shown that boiling a potato for around eight minutes can increase its capacity as a battery 10 times compared to a raw potato. Sandwiching a quarter of a boiled potato between a copper cathode and a zinc anode can power a lightbulb for 40 days.
Current and Voltage
Perhaps not surprisingly, several pieces of fruit or vegetables connected in a parallel circuit creates a higher current. If the fruit or vegetables are connected in a series arrangement, the voltage is increased. This, in turn, can be used to power increasingly complex machines and electronics like a wristwatch.
Science Project on Electricity in a Potato
Potato & Battery Science Projects
Creating an electric battery out of an ordinary potato is a popular science project for middle-school students. In most commercial batteries, electricity is generated by a chemical reaction between two electrodes (copper and zinc) and an electrolyte (sulfuric acid). The liquid in a potato can act as the electrolyte and generate electricity between two electrodes. This experiment teaches students about chemical reactions and electricity and encourages observational and analytic skills.
100% Natural Energy: How You Can Create Electricity From Fruits
The health benefits of eating fresh fruit are undeniable, but wouldn’t it be great if it could be used for something else other than fuelling your body. Like, say, making electricity?
As it turns out, with some lateral thinking, fruit can be used for just that purpose!
This is not only interesting as a concept but with ever-increasing amounts of waste food, like fruit, being generated every day, it could also be a way of making “money for old rope.” In fact, in the US alone, somewhere in the region of 150,000 tons of waste fruit and vegetables are thrown away every single day.
This is not only incredibly wasteful, but it is potentially harmful to the environment. If only this wasted food could be used for something else?
Like sustainable energy, for example.
Can you use fruit as a battery?
Interestingly enough, you can, well, sort of.
One way to generate electricity from fruits is to make basic batteries using electrodes and whole pieces of fruit. The acids within the fruit, namely citric acid, can be used, with the application of some science, to turn the fruit into a kind of rudimentary battery.
Just like in conventional batteries, the acids interact with electrodes to generate small amounts of current that can be tapped and used to power small electronic devices.
A fun piece of home science, you can experiment with different pieces of fruit (or vegetables, for that matter) to find the best fruit-battery subjects.
Using some basic materials, like two different metals (zinc and copper work best) to make electrodes, this experiment is a relatively simple and effective activity to share with your kids. Either suspend the metal electrodes in some fruit juice or insert them into an intact piece of fruit to generate some small amounts of voltage.
Amazing, but how does it work?
As in regular batteries, the electrodes will act as the cathode and anode, allowing a small electrical current to be generated. The citric acid in the fruits acts as a kind of electrolyte that reacts with the metal electrodes to generate ions.
This is because organic material can act as an ionic conductor. These substances allow ions to freely move through them.
It works because the zinc electrode (cathode) will also react with the citric acid to produce cations and free electrons. These electrons then slowly build up on the zinc cathode and, once a wire is attached, will flow through the wire.
With the wires connected to the copper cathode to complete a circuit, the electrons begin to react with hydrogen cations in the fruit, eventually leading to the formation of hydrogen gas. This process will continue as long as the electrolytes are present and the electrodes are intact — i.e. until the fruit dries out or an electrode dissolves.
The juice of the fruit will also conduct electricity, effectively completing the circuit. This works in a similar way that salt solution can also conduct electricity.
Unless you have ready-made examples lying around the house, you can use a copper-plated penny and a galvanized nail. Galvanized nails are often made of iron with a coating of zinc.
With this kind of setup, you may be able to generate a small amount of current (about 0.5 to 3/4 of a volt) from a single piece of fruit. Vegetables, like potatoes, can produce a little more, often just over 1 volt.
Lemons, as it turns out, can produce up to 0.96 volts.
Not much, but you can connect several fruit pieces in parallel to up the voltage. You may even be able to produce enough current to charge something like a mobile phone. The more fruits you need, it might become easier and more efficient to just use a regular charger.
The highest voltage achieved from a fruit battery was 1,521 volts by Alssundgymnasiet Sønderborg high school in Sønderborg, Denmark, on 29 January 2020. However, it took 1,964 lemons to achieve.
Depending on the type and number of fruits, the voltage might be enough to power a small LED or even a small motor. As it turns out, the best fruits and vegetables to use are those that high in conductive ions like potassium or sodium.
It also helps if they have the “right” internal structure to create working currents. More homogenous fruits, or vegetables like potatoes or pickles, are excellent choices.
Fruits like oranges are actually often a poor choice as their internal structure is partitioned into compartments, separated by membranes, which act as barriers. This will block the free flow of current.
Fruit can also be used in microbial fuel cells
In a different approach from the basic fruit-battery described above, researchers are looking into creating electricity from fruit more sophisticatedly. One example is called a microbial fuel cell (MBCs) that can be used to convert fruits and vegetables into useable electricity.
MBCs are effectively bio-electrochemical devices that can generate electricity using a wide range of microorganisms. A team of researchers from Ecuador experimented with this technology using membrane-less single chamber MCBs over 60 days.
The experiment was very fruitful, excuse the pun, and was able to produce an output voltage of 330 mV.
You can also generate electricity from rotting fruit
Using fresh fruit as a kind of ad hoc battery is one way to generate electricity from fruit, but there is another way. As the fruit decomposes, methane gas is produced, which can, in turn, be combusted to generate power on a much larger scale.
This is exactly what authorities in Seville, Spain, have proposed as a way to kill two birds with one stone. The city’s streets are filled with Seville orange trees. Farms in the region export almost all of the Seville oranges they grow to Britain, where they are turned into marmalade. But the residents of Seville don’t eat the bitter fruits, so the city ends up with streets littered with rotting oranges.
These fallen oranges not only present a hazard for pedestrians but are also a headache to clean up for city authorities. The oranges are often squashed underfoot or by the wheels of cars, leaving streets sticky with juice and swarms of flies.
Currently, 200 people are employed to collect the fruit every year.
In February 2021, a new pilot scheme was announced to put this waste fruit to use, rather than simply chucking them all into a landfill.
The fruit is gathered up and taken to a municipal water company, Emasesa, which generates clean energy from it to run one of its water purification plants. The juice is extracted, combined with other organic matter, and used to produce biogas, while the peels are being composted and transformed into fertilizer for fields.
“The juice is fructose made up of very short carbon chains, and the energetic performance of these carbon chains during the fermentation process is very high,” said Benigno López, the head of Emasesa’s environmental department in an interview with the Guardian. “It’s not just about saving money. The oranges are a problem for the city, and we’re producing added value from waste.”
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Why Do Some Fruits and Vegetables Conduct Electricity?
At any science fair, you’re almost guaranteed to see at least two go-to experiments: the clichéd papier-mâché volcano and the ever-popular pickle or potato battery. Many people may think it’s amazing that a simple piece of produce can conduct electricity. As it turns out, that’s not the whole story.
There are many types of electrical conductors. These include traditional electrical conductors, such as the copper and silver wires that are used to run electrical currents in homes and buildings, and ionic conductors, which can power electricity via free moving ions. Organic material, such as human tissue or the potato in your science experiment, are ionic conductors that create ionic circuits. Electrolytes — chemical compounds that create ions when they are dissolved in water — in these materials do all of the work.
“Fruits and vegetables conduct electricity in the same way a salt solution will complete an electrical circuit,” Michael Hickner, an associate professor of materials science and engineering at Penn State, told Live Science. “It’s due to the ions in the salt solution. They don’t conduct electrons [as traditional electrical conductors do]
An ionic conductor contains positive and negative charges — otherwise known as charged ions — that move freely when they come into contact with a voltage. For example, when table salt is dissolved in water, the sodium and chloride — which have opposite charges, as Na+ and Cl- — create an ionic solution, Hickner said. These ionic solutions are called electrolytes and can be found in every living thing. Because of this, technically, any fruit or vegetable could become an ionic conductor, but some are better at it than others. This is also why salt water or unfiltered tap water are better ionic conductors than filtered fresh water.
The best food battery is any fruit or vegetable that has high levels of superconductive ions, such as potassium or sodium, and the proper internal structure to create a working current. Potatoes, which have homogenous structures, and pickles, which have high levels of sodium and acidity, are good examples of such foods. For an extra electrical “oomph,” you can soak your potato in salt water before setting up the potato battery experiment, Hickner said.
In contrast, tomatoes have unorganized, messy insides and often leak, and even an orange — which has high levels of potassium— won’t work well, because the flesh of the fruit is divided into internal compartments, and these create barriers that block the current, Paul Takhistov, an associate professor of food engineering at Rutgers University in New Jersey, told Live Science.
Fruit and metal
Some fruits and vegetables may be chock-full of superconductive ions, but you’ll need a few more materials to turn these foods into batteries. The voltage from the battery comes from electrodes made of two different metals, such as copper and zinc, Hickner said. You can easily make a potato or pickle battery using a copper penny and a galvanized nail (which is usually made of iron coated with zinc).
“The fruit or vegetable can’t conduct on its own. It needs something to drive the ions,” Takhistov said. “When you insert two different metals and connect them with wire, you create an electrical circuit. Then, when this material is brought in contact with the electrolytes, the battery reaction starts to generate the voltage. Because of the difference in electrical potential energy between the two metals, the positive and negative ions will begin to move freely.”
But could a potato battery power, for example, a phone? Probably not.
A potato battery can produce only about 1.2 volts of energy. Takhistov said you would need to link many potato batteries in parallel to create enough of a current to charge a device like a phone or tablet. “At that point,” Takhistov said, “it’s probably just easier to use your phone charger.”
How to Make a Fruit Battery
Use fruit to generate electricity for a light bulb
If you have a piece of fruit, a couple of nails, and some wire, then you can generate enough electricity to turn on a light bulb. Making a fruit battery is fun, safe, and easy.
What You Need
To make the battery you will need:
- Citrus fruit (e.g., lemon, lime, orange, grapefruit)
- Copper nail, screw, or wire (about 2 in. or 5 cm long)
- Zinc nail or screw or galvanized nail (about 2 in. or 5 cm long)
- Small holiday light with 2 in. or 5 cm leads (enough wire to connect it to the nails)
Make a Fruit Battery
Here’s how to make the battery:
- Set the fruit on a table and gently roll it around to soften it up. You want the juice to be flowing inside the fruit without breaking its skin. Alternatively, you can squeeze the fruit with your hands.
- Insert the zinc and copper nails into the fruit so that they are about 2 inches (5 centimeters) apart. Don’t let them touch each other. Avoid puncturing through the end of the fruit.
- Remove enough insulation from the leads of the light (about 1 in. or 2.5 cm) so that you can wrap one lead around the zinc nail and the other lead around the copper nail. You can use electrical tape or alligator clips to keep the wire from falling off the nails.
- When you connect the second nail, the light will turn on.
How a Lemon Battery Works
Here are the science and chemical reactions regarding a lemon battery (you can try making batteries from other fruits and from vegetables):
- The copper and zinc metals act as positive and negative battery terminals (cathodes and anodes).
- The zinc metal reacts with the acidic lemon juice (mostly from citric acid) to produce zinc ions (Zn2+) and electrons (2 e–). The zinc ions go into solution in the lemon juice while the electrons remain on the metal.
- The wires of the small light bulb are electrical conductors. When they are used to connect the copper and zinc, the electrons that have built upon the zinc flow into the wire. The flow of electrons is current or electricity. It’s what powers small electronics or lights a light bulb.
- Eventually, the electrons make it to the copper. If the electrons didn’t go any farther, they’d eventually build up so that there wouldn’t be a potential difference between the zinc and the copper. If this happened, the flow of electricity would stop. However, that won’t happen because the copper is in contact with the lemon.
- The electrons accumulating on the copper terminal react with hydrogen ions (H+) floating free in the acidic juice to form hydrogen atoms. The hydrogen atoms bond to each other to form hydrogen gas.