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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Is it weight? A banana weighs about 125g. So, around 15tonnes per forty footer. That's far short of the maximum of 28 tonnes.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
So what is it? It's power.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Even the biggest container ships - for example, the Emma Maersk with around 11k fully laden TEUs - only have 1k reefer sockets onboard. Assume those are all filled with forty footers. We are down to around 1k * 120k = 120 MegaBananas.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Wow, big difference! But, it gets worse. Those reefer positions all need power.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
We used to factor around 4kW for a reefer... so that would be around 4MW total. Easy! Problem is, bananas are not average. Most frozen cargo is taken onboard frozen. It doesn't take much power to keep it frozen at -21degC
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Bananas are different though - they are often packed warm, and brought directly to the ship. They are also kept at +14degC. This means the refrigeration needs to work harder.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
We are now looking at as much as 20kW to cool that container when it comes onboard, and 8kW to maintain the temperature. We've jumped to 8MW at least! That's changed what you are doing in the engine room.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Each of the 5 generators on the Emma Maersk is around 4MW. You are now running 3 generators just to keep the ship running in port!
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
Worse still, the shaft generator (the thing that recovers power from the main engine) is only 8.5MW. You are now having to run extra generators. Not economical. But doable.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
So where does all that heat go from the refrigerated containers? The air. That's fine above the hatches. But what about below the hatches? Well, you need fans. And a lot of them.
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Cybergibbons! (Project Zero Hounslow)
No container ship I worked on had enough below hatch ventilation to handle 100% bananas. 100 containers dumping 8kW of power under a hatch is a lot. Total guess, but I don't think you'd manage more than 75% of reefer being at full load.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
So I think at best... we have 750 * 120k = 90 Mega Bananas. Enough for everyone in the UK and me.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
How do shipping companies handle this? Well, there are actually special banana ships - they are open hatch and can easily handle the load. Anyway, hope that was fun :)
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @cybergibbons
This is what happens when you just multiply containers by how much you think is in them.
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Cybergibbons! (Project Zero Hounslow) 5. sij
Odgovor korisniku/ci @cybergibbons
For those of you interested in what the engine room of a container ship looks like, I posted some pictures last year:
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Jani 4. sij
Odgovor korisniku/ci @cybergibbons
This is the exact sort of thing I am on Twitter for.
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Cybergibbons! (Project Zero Hounslow) 4. sij
Odgovor korisniku/ci @janipewter
Next up, I trace down who made that beer mat and finish them.
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🛢 5. sij
Odgovor korisniku/ci @cybergibbons
It’s actually way more heat that this…due to the thermodynamic magic of heat pumping, using 8kW of electricity can move WAY more than 8kW of heat from inside the container to outside. Like several times more.
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Cybergibbons! (Project Zero Hounslow) 5. sij
Odgovor korisniku/ci @jobead
True. I didn't get that right. I just know that it hits capacity - with ambient getting to 45-50degC, which makes the refrigeration less efficient... things stop working.
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Traci 🐟 6. sij
Odgovor korisniku/ci @cybergibbons
My area is food & ag. My spouse is a ship engineer. We are studying this thread.
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