---
title: 'What If It Rained Bananas for a Single Day? (Spoiler: It''s Bad)'
source: 'https://youtube.com/watch?v=tRXy-b6_lBc'
video_id: 'tRXy-b6_lBc'
date: 2026-07-28
duration_sec: 675
channel: 'Kurzgesagt – In a Nutshell'
---

# What If It Rained Bananas for a Single Day? (Spoiler: It's Bad)

> Source: [What If It Rained Bananas for a Single Day? (Spoiler: It's Bad)](https://youtube.com/watch?v=tRXy-b6_lBc)

## Summary

This humorous and scientifically playful video from Kurzgesagt explores two absurd questions: whether Tokyo can be powered by jellyfish and what would happen if it rained bananas for a day. Using real physics and biology, the video calculates the staggering scale of both scenarios, revealing apocalyptic consequences for the banana rain idea.

### Key Points

- **Powering Tokyo with Jellyfish** [00:24] — To meet Tokyo's annual electricity demand of 280 TWh, you would need about 29 billion Nomura jellyfish wrapped in piezoelectric nylon, each generating 10 kWh per year.
- **Piezoelectricity Explained** [01:48] — Piezoelectricity is an electric charge that builds up in certain materials (like quartz or bone) when stressed. In the jellyfish plan, twitching tentacles bend nylon nanofibers to generate electricity.
- **Jellyfish Power Output** [03:32] — Each Nomura jellyfish with 1000 tentacles wrapped in piezoelectric nylon produces about 1 watt, or 10 kWh per year – enough to run a laptop for 20 days.
- **Banana Rain Scenario** [05:10] — If all rain for one day was replaced by bananas, 1.33 trillion tons of fruit would fall – equivalent to a 14 km wide water sphere. That's 11.1 quadrillion bananas.
- **Caloric Overload** [06:13] — The total calories from one day of banana rain (1.2 quintillion) could feed the entire world population for over 100 years.
- **Impact Destruction** [06:42] — Bananas falling from 3000 meters hit at 240 m/s, with kinetic energy equal to a bowling ball dropped from 50 meters. London alone would face 21 billion bananas.
- **Methane Catastrophe** [07:41] — Rotting bananas would release 160 billion tons of methane – 280 times current annual emissions – causing a sudden, catastrophic global temperature spike and mass extinction.

### Conclusion

The banana rain scenario is an apocalypse-level event that would destroy infrastructure and trigger a mass extinction, while the jellyfish power plant is impractical yet mathematically amusing.

## Transcript

Today, we are answering the stupidest –  uhm, ok wait, the BEST and MOST AMAZING questions from you – our viewers! At kurzgesagt, we’re experts when it comes to  
tackling stupid questions, and on top of our own,  we get hundreds from you on an almost daily basis! So let’s very seriously and  scientifically answer some of them!
Question 1: How many Jellyfish do you need to power Tokyo? Tokyo is a hungry beast, gobbling up around  280 terawatt hours of electricity every year. That’s more energy than these twenty countries  combined, and more than all of Australia.
Can we power Tokyo with our  innovative renewable energy source? Some jelly species like Aequorea victoria or  Crystal Jelly contain fluorescent proteins   and glow in the dark. If you put one  of them in front of a tiny solar panel,  
you’d end up with something like a microwatt  hour of energy. To meet Tokyo’s outrageous energy demands, you’d need: a quintillion  three hundred quadrillion glowing jellies.
How about Nemopilema nomurai, the  Nomura jellyfish! Really chunky boys, weighing about as much as a piano and growing up  to 2m wide, they’re armed with around a thousand
spindly tentacles that grow up to four meters long  and help them suck up plankton from the water. In recent years, their numbers have been exploding, wreaking havoc on local ecosystems. Using these fridge-sized jellies to power  Tokyo will finally give them something  
more useful to do. They don’t glow in the dark but jellyfish are kind of electric, aren’t they? If you’ve ever been stung by a jellyfish you know it feels like a painful electric jolt –
but the pain actually comes from hundreds of nematocysts inside their tentacles, So how do we get energy from jellyfish? We’ll squeeze it out of them with the power of piezoelectricity!
Piezoelectricity is an electric  charge that builds up in certain solid materials like crystals or bone when you stress and squeeze them. For example, a quartz crystal is made up of positive and negatively charged atoms
Their charges usually cancel each other out. But if you apply enough pressure, atoms shift out of place and the pyramids become  kind of wonky. Positively charged on one side  
and negatively charged on the other – like a  battery. Together they add up to a charge across the whole crystal. Piezoelectricity  powers sonar, times quartz watches,   and some nightclubs use it to keep the lights  on just from the stamping of dancers’ feet.
So, here’s the plan: we will create a  ginormous battery from jellyfish by harnessing   the hypnotic movements of Nomura’s hundreds of long, thin tentacles. one tentacle at a time, into a kind of wetsuit  made from nylon-11,11: a cutting edge material  
that has been optimized for power production and  has the same piezoelectric properties as quartz. Next, we watch as each twitch of a tentacle bends  the tiny nylon nanofibers of the jelly suit,   converting its movements into electricity.  All we need to do now is to plug our jelly
into a current collector with a copper  cable to be utterly disappointed. Even with around 1000 tentacles  wrapped in energy-generating nylon, the electricity generated only adds up to around 1 Watt, or 10 kWh per year.
Enough energy to run your laptop for twenty days. Not bad, but we want to power Tokyo here! We need more jellies! WAY MORE!  About 29 billion! Sounds like a lot,  
27 billion chickens alive on Earth. So it's mostly a matter of motivation on our part. A single Nomura can produce millions of jelly  babies a month, and with enough plankton to eat,  
they can grow from the size of a grain of rice  to the size of a person in less than a year.   all we need to do is to basically  empty the Pacific of plankton. And of course we’ll need space to store  them all. Giving each Nomura a cube of  
space measuring 5 meters on each side sounds  generous, but it barely contains the tentacles.   All those jelly-cubes add up to a tank that’s  about seven times the total volume of Mt. Fuji. With all those tentacles and cables, our  biggest issue will be short circuits.  
We need to insulate all 29 billion cables. And  don’t forget the tentacles themselves. Now, even   if the jellies get tangled up, we can maintain a  steady power supply for the good people of Tokyo.
In reality of course, our jellyfish powerstation  would be pretty difficult to maintain. Nomura would probably die constantly and need to be replaced. And the cost of building this whole mess and killing the ocean  to feed them would be like spending  
We’re not saying any of this is a good  idea. But now we've done the math, Okay, bring on the next totally dumb,  – uhm, completely reasonable question!
What if it rained bananas instead  of water for a whole day? Ok, so first, we tried to calculate what  would happen if for one day every single   rain droplet was now a banana. Turns out in  a storm, several million raindrops can fall  
on a single square meter. Which stacks  quickly to the equivalent of a banana   asteroid smashing into the planet and killing  all life. While fun, this is a bit too much. Instead let’s take the average volume of rain  that falls on our planet in a single day,  
about 1.33 trillion tons of water – a massive,  wobbly orb of water 14 kilometers across. Each fruit weighs about 120 g, which will give us  a daily banana-fall of 11.1 quadrillion bananas,
weighing 1.33 trillion tons in total. If  we match average global rainfall patterns,   even the Sahara Desert would  receive around 15 trillion bananas. If a medium sized banana has about 105  calories, 15 trillion Sahara bananas alone  
could already feed the world’s population for  over two months. For the world as a whole the   calories of all rain bananas add up to a grand  total of 1.2 quintillion calories. With just   one day of banana rain we could go on feeding  everyone on Earth for over a hundred years.
Of course in reality, the banana  rain would be pretty catastrophic. A banana falling from about 3000 meters,  the height of a mid-altitude rain cloud,   would reach a velocity of 240 meters per  second and strike the ground with the same  
kinetic energy you’d get from dropping a  bowling ball off a 50 m building. And we   are dropping almost thirteen over eleven  quadrillion of them across the planet. One of the rainiest and therefore worst affected  cities is London. It would face a storm of 21  
billion bananas, or 2.5 million tons. The shower  of yellow death breaks roofs, shatters windows,   and decimates national monuments. Human  bones are no match for this monsoon,  
so we’d need to take shelter from the  banana blitz inside or underground. All around the world, cities and infrastructure,  rivers and rainforests are severely damaged and   clotted with a layer of banana smoothie  that’s already beginning to rot. Trillions  
of mashed bananas are floating in  the ocean, clogging up coastlines. Picture the aftermath of all the worst oil  spills and superstorms combined but way   worse and kind of everywhere. And our problems  are just getting started. The rotting banana  
mush contains 160 billion tons of methane,  280 times our current annual emissions as   a planet. Methane traps around 28 times more  heat than CO2. Adding this much greenhouse gas  
this quickly will lead to a catastrophic  and sudden spike in global temperatures.   Most ecosystems won't be able to handle it and  we’ll witness a devastating mass extinction event. In short, Banana rain is an  apocalypse-level catastrophe.
Ok, hopefully your question has been properly  answered. It's time to wrap up for today – please keep sending us your amazing questions,  even and especially if they are stupid, we are collecting them and will  answer more of them in the future!
Well, that escalated quickly! Like that time   I downloaded some random software from  a sketchy website – not stupid at all. We tried out NordVPN to avoid that sort of  catastrophe. Go to NordVPN.com/Kurzgesagt  
to make sure malicious websites are blocked,  webtrackers stopped and pesky ads are hidden.   NordVPN’s Threat Protection scans files  during downloads and removes malware and   trackers automatically - and they warn you of any  apps that seem risky – I am looking at you there!
On top, NordVPN offers many more features:  Summer is travel season and NordVPN encrypts   airports or cafés. You can choose from over 7,000  fast servers in 111 countries around the world.
So you can also access your home content  from abroad. You can also book flights,   different countries - regardless of whether you  are surfing with a computer, tablet or smartphone.
NordVPN is compatible with all major  platforms and can be used on 10 devices   simultaneously. If you want to discover  all the services NordVPN offers go to  NordVPN.com/Kurzgesagt to get 4 months extra  
on a 2-year plan - all risk-free with  NordVPN's 30-day money-back guarantee.