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Brilliant is offering a 30-day free trial and 20% off an annual premium subscription when you sign up at brilliant.org/SciShow. When you think of newer ways  to generate electricity, maybe you think of renewable  energy sources like solar or wind.

But scientists can make the  stuff from just about anything. And some of those ways of generating  electricity are a lot weirder than putting turbines in a corn field. Like, who would have thought you could  power an underwater camera with sound?

Or charge up a Mars rover with  warmth coming from the thing itself. Or run your electronics on plants. We’re about to explore a few shocking  new ways to make electricity. [♪ INTRO] In 2022, MIT researchers made a prototype camera meant for underwater missions  that uses sound to power itself.

But before I can explain how it works, we need a quick lesson on the  magic of piezoelectricity. The term has two root words. Electric, obviously, and piezein, a Greek  word that means “to squeeze” or “to press”.

Put them together, and you have  electricity that comes from pressure. It refers to the electricity you  get from some solid materials when you put pressure on them. Piezoelectric materials can be crystals, ceramics, or even biological materials like bone.

But what they all have in common is  deep within their crystal structure, the way their molecules are arranged. In most solid materials, molecules  are arranged in rigid structures, and are bonded to each other  based on their electrical charges. Positive molecules bond with negative molecules, which bond with positive molecules and so on.

When non-piezoelectric materials are  squeezed, the positive and negative ions within the structure come together  evenly, so no electricity is formed. But piezoelectric materials have molecules  that are arranged in a different way. Because when they’re squeezed, the  positive and negative ions get kind of pushed out of place, forcing electrons  to move from one ion to another.

And any movement of electrons creates electricity. We use this effect in many electronics,  from quartz watches to smoke alarms. But we can also use piezoelectricity  in more sophisticated devices.

Which brings us back to those MIT  researchers and their underwater camera. They wanted to see if they could  use the ambient sound of the ocean to power the equipment. Remember, sound is just pressure  waves, moving through a medium.

The prototype camera they built works  because it’s covered in piezoelectric transducers, a part that converts  energy from one form to another. And they tested it using an  artificial acoustic source. The sound waves apply pressure to the  transducers, producing electricity.

And then, capacitors in the  camera store the electricity so it only works when it has  enough energy to do its job. The camera’s imaging sensor  uses very little power, and can only capture grayscale images. But the team figured out how to capture  color images by taking three pictures in a row with three different LED  flashes - red, green, and blue - and then overlaying them on top of  each other to create the perfect photo.

It also uses sound to transmit data! Currently, the prototype can only  reliably send data about 40 meters away. So it’s not something that deep sea  explorers will be using this weekend.

But the technique requires a lot  less energy than traditional methods and it promises to be a  breakthrough when they perfect it. Do you remember when NASA’s  Opportunity rover went offline in 2018? As best as we can tell, poor Oppy was  caught up in a Martian dust storm, which clouded its solar panels  and made it impossible to generate enough power to function.

But, perhaps not surprisingly, Opportunity  was one of the last NASA rovers that was powered mostly by solar panels. So the new ones, like Curiosity and Perseverance, they have a different energy source. They run using heat.

These rovers are powered using a device called a Radioisotope Thermoelectric Generator, or RTG. They work by converting the heat generated by the decay of  plutonium-238 into electricity. And to unpack this, we have  to take a few steps back.

So, Plutonium-238 is a radioactive isotope, which means it naturally decays to  a more stable isotope over time. And that process produces heat. We can take advantage of  that heat using a phenomenon known as the Seebeck effect.

So, if you have two electrical  conductors with a temperature difference, electricity will flow between them. Heated electrons always travel from  warmer objects to cooler objects. So when you heat one conductor, a charge flows from the hot  conductor to the cold one.

We’ve known about this for a long time. In fact, some people out there  might have had pacemakers powered by a plutonium generator. NASA loves using thermoelectric  generators for their space missions because they have no moving parts  that often need to be replaced.

So that makes them a really reliable power option. In their RTGs, the radiation  heats up one conductor, while the icy void of space or the frigid  Martian landscape keeps the other one cold. And thermoelectric power  isn’t just limited to space.

A Canadian teen once made a flashlight and a headlamp powered by her own body heat. Which is a pretty cool trick! But it relies on the temperature outside  being different enough from your body.

So if I was wandering around  in a dark forest at night, I’d probably just want to bring a backup battery. This next entry on our list of weird  ways to make electricity involves light. But it makes use of a technology  much older than solar panels.

I’m talking about photosynthesis. We’re all vaguely familiar with it, right? Plants turning light into food.

But that’s not a one-step process. Photosynthesis is a series of chemical reactions that convert carbon dioxide and  water into oxygen and sugar. These reactions require  energy from light to progress.

So, the type of chemical reactions that  occur during photosynthesis are called oxidation reactions, which involve  electrons transferring between atoms. And as we’ve already learned,  moving electrons mean electricity. Enough electricity to measure for sure.

And maybe, enough electricity to harness. Researchers are currently looking  into ways to grab some electricity from photosynthesizing plants. And if they succeed, this would be a bonus  for the climate, because photosynthesis takes carbon dioxide out of the air  instead of adding more into the atmosphere.

But while we can see that photosynthesis  causes electrons to move around, the challenge is measuring  and capturing that current. To figure out the measuring part,  researchers from Israel took a succulent leaf and placed an anode and cathode  into two different sides - essentially adding the positive  and negative ends of a battery. And because succulents contain so much  water, the scientists hypothesized that the interior of the leaf would  act as the fluid of the battery, carrying charge from one end  of the system to another.

And they were able to measure how much electricity travels through a single leaf in a day! They found that a succulent  leaf generates about 0.28 volts. Which is … not much.

For context, a single car  battery generates about 12 volts. But multiple leaves can be strung  together to create a circuit, giving the plants a bit of a boost. Other researchers have started looking into  cyanobacteria, which is a type of marine bacteria that photosynthesize, in order to  figure out how to harness that electricity.

Cyanobacteria are the original photosynthesizers. They invented the technique, and their evolution is the reason that life  as we know it can exist on Earth today. And it looks like they’re still helping us out.

By observing these bacteria, researchers  from the University of Cambridge found that the start of  photosynthesis is a “leaky” process, meaning, like, the electrons “leak”  out of the photosynthetic system. The finding is so new that researchers  are still working on a solution for grabbing that charge. But the discovery that electrons are released, instead of just continuing along  the photosynthetic pathway, means it’s going to be easier to access  them and use the power that they create.

And because there are a lot of cyanobacteria, it could be a huge source of renewable energy,  and it’s literally as green as it gets. There’s one more weird source of  electricity we haven’t talked about yet, and it has to do with the air we breathe. Or to be more specific, a part of the air  we don’t use when we breathe: hydrogen.

A soil bacterium called Mycobacterium  smegmatis has been discovered to contain an enzyme that can convert the  hydrogen gas in the air into electricity. We’ve been considering hydrogen as  an energy source for a while now, but our ideas mostly have to do with  burning it to get that sweet, sweet energy. And these bacteria seem to be skipping a step.

They initiate a chemical reaction  that breaks up hydrogen gas, oxidizing the individual hydrogen atoms. Like we mentioned before in photosynthesis, oxidizing reactions move electrons  around, leading to an electrical charge. The enzyme that catalyzes that  reaction is called hydrogenase, and we’ve managed to isolate it.

So, the next step would be to produce hydrogenase in large enough quantities to be useful. Right now, we can manufacture the stuff  in milligrams, but we’d need to bump those numbers up to grams or even kilograms  before we can use it commercially. But scientists are hopeful  that we can build devices powered by the enzyme in something like a battery.

These would be small. Think clocks, LEDs, or even simple computers. But having these devices could take  some of the strain off of overloaded grids or provide power in places without  other reliable electricity sources.

Another air-based electricity source might  be able to generate a lot more power, and I’m not talking about the wind. Researchers have found a way  to make a synthetic cloud that generates electricity from humidity. Yeah, that stuff that makes you  stick to your shirt in the summer might actually have a use.

They call it a “cloud’  because water and electricity can move through it the same way  they move through storm clouds. But it’s actually made of a thin  sheet of engineered material. Apparently, almost any material could work, as long as the synthetic  cloud is full of tiny pores.

Because those pores are so small, the water molecules bump into the  cloud material on their way through. And just like rubbing your feet on the  carpet generates static electricity, the water molecules that bump into  the cloud end up generating a charge. They make that charge right at the top  of the cloud, when they first enter.

This creates a charge imbalance  between the two sides. Essentially, a battery. Now, they’ve only tested it with  one thin layer of cloud so far, but they’re hoping to scale this up to  three dimensions, creating even more power.

If you’re worried about blotting out  the sky with monster clouds, don’t be. When we say they’ve made a thin layer of cloud, we’re talking about something  that’s the width of a human hair. Up to a thousand of those layers stacked  on top of each other wouldn’t take up that much room, and researchers think that if  we could build a synthetic cloud that big, we could deliver power on the order of kilowatts - enough power to feed into the electrical grid.

And it would work 24/7, rain or shine. At least, in places with humidity. All these ways of generating electricity  require more research to make them viable.

But the same could be said about  solar panels just a few decades ago. It’s not just extreme environments like space and the deep sea that will call for  novel ways of powering our devices. Our desire to create enough  electricity for everyday use without destroying the planet demands it.

And it all starts with the spark of an idea. Hey! Stefan here.

And we just talked

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