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Mexico building rail rival as water shortages drain Panama Canal

japantimes.co.jp

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Re: Mexico building rail rival as water shortages drain Panama Canal

#101

Post by RagnarD »

jodrellblank wrote: post #93
RagnarD wrote: post #90

I'm wondering why the whole thing is an issue anyway. Why is there a water shortage? There's an entire ocean on both sides of the canal. Gatun Lake provides the water buffer for the canal. Currently it's freshwater based but it's also artificial to begin with. Why not transition to using salt water pumped from the oceans to top it off as needed? Seems a hell of a lot easier than trying to replace the canals with rail…

"Every ship traversing the canal between the Atlantic and Pacific oceans requires 50 million gallons of fresh water"[1]. And it can transit 40 ships per day[2]. So, lifting 2 billion gallons of water, just over 9 billion litres, up to the 26 metres altitude of Gatun Lake. Wondering how plausible that is, the numbers match very closely to the Dinorwig pumped-storage hydroelectric power plant in the UK[3], which stores…

Good idea as well.

Re: Mexico building rail rival as water shortages drain Panama Canal

#102

Post by creer »

timeagain wrote: post #92
RagnarD wrote: post #90

I'm wondering why the whole thing is an issue anyway. Why is there a water shortage? There's an entire ocean on both sides of the canal. Gatun Lake provides the water buffer for the canal. Currently it's freshwater based but it's also artificial to begin with. Why not transition to using salt water pumped from the oceans to top it off as needed? Seems a hell of a lot easier than trying to replace the canals with rail…

Gatún Lake is 425 km^2. It provides the drinking water for Panama City. It has a watershed covering a large portion of the country. You might be underestimating the scale of the problem.

It's not the lake that needs to be filled. Just the locks - and the lower ones at that.

Re: Mexico building rail rival as water shortages drain Panama Canal

#103

Post by dave333 »

pxeboot wrote: post #74
cowthulhu wrote: post #66

Earlier quoted context omitted.

I’m pretty sure once you cede that you’re willing to use the energy required to move a container ships worth of weight from one end of the canal to the other, the cheaper option would be to pump water to refill the locks. Water is easier to transport than ships, and while I don’t think the efficiency of the locks helps much in this context, there might be some clever optimizations… especially if you’re willing to run…

Pump it from where though? It would be easy to pump and reuse the water that already goes through the locks, except that it gets mixed with salt water, so putting it back in the lake would quickly contaminate it.

Pumping sea water to the top of the lock chain or maybe the lock next to the top would save a lot of fresh water but would slowly contaminate the lake unless there were some kind of double gate to prevent sea water used to fill the top lock leaking out when a ship enters the lock from the lake.

Re: Mexico building rail rival as water shortages drain Panama Canal

#104

Post by dave333 »

pxeboot wrote: post #74
cowthulhu wrote: post #66

Earlier quoted context omitted.

I’m pretty sure once you cede that you’re willing to use the energy required to move a container ships worth of weight from one end of the canal to the other, the cheaper option would be to pump water to refill the locks. Water is easier to transport than ships, and while I don’t think the efficiency of the locks helps much in this context, there might be some clever optimizations… especially if you’re willing to run…

Pump it from where though? It would be easy to pump and reuse the water that already goes through the locks, except that it gets mixed with salt water, so putting it back in the lake would quickly contaminate it.

Based on the diagram of the locks and water saving basins at https://en.wikipedia.org/wiki/Panama_Canal_expansion_project... they could have a second basin D at the same level as basin C. They would pump the fresh water in C that has come down the lock chain back up into the lake. They could pump sea water into D that would be used to fill the bottom lock when a ship is acsending the chain. Then the sea water in the bottom lock would be drained to the sea when a ship descends.

Re: Mexico building rail rival as water shortages drain Panama Canal

#105

Post by myself248 »

jodrellblank wrote: post #96
myself248 wrote: post #67

Earlier quoted context omitted.

Agreed, pumping sea water seems terrible, but it also seems like there'd be no reason to do that. First, at either end of the system there's a chunk of river at sea-level-ish but flowing towards the sea, so the water up at the upstream end where the lower locks are is probably not salty at all. Second, if each lock had its own pumps, doing it in 3 short lifts rather than 1 big lift to the top, then even if the one or…

I did my own estimate ( https://news.ycombinator.com/item?id=38997124 ) via a different method, before reading down to yours, and got ~450MWh of energy needed - which is close enough to your 521MWh that I'm pretty happy. > " Nah. Let's do it with solar. " Why not with hydroelectric? Store power by pumping water up to Gatun Lake, generate power while filling the locks as the water falls down...

> which is close enough to your 521MWh that I'm pretty happy.

Nice! And Dinorwig runs around 72% round-trip efficiency, which is higher than I expect to see here simply on account of scale, but also in the ballpark.

> generate power while filling the locks as the water falls down...

Now that's an interesting one.

There are already lock systems where there's two parallel chains, and the ascending and descending locks operate in lock-step, with the two locks first equalizing water with each other, before the ascending takes water from above and the descending releases water to below. So that doubles the amount of traffic that can be handled by the same amount of water.

Presumably building twice the infrastructure would be cost-prohibitive or they would've done it over the preceding decade, but storing the water's energy could be quite a bit cheaper and smaller.

Edit: Much simpler, takes more space, saves almost as much water: https://en.wikipedia.org/wiki/Panama_Canal_expansion_project...

It ends up being a lot like linking the shafts of all the pumps, with extra steps for control, eh?

Edit: Oh. Yeah. Okay, at each lock, you've got three pumps on a common shaft, with clutches:

(fill turbine)--[clutch]--(lift pump)--[clutch]--(drain turbine)

Whether you're filling or draining, you clutch that turbine to the lift pump, and lift some water upward as the working water flows downward. No electricity needed.

Hmm. Alright, who wants to go pitch a project?

Re: Mexico building rail rival as water shortages drain Panama Canal

#106

Post by jodrellblank »

fragmede wrote: post #99
jodrellblank wrote: post #97

Earlier quoted context omitted.

What if we built Robert Bartini's Ground Effect Aircraft Carrier https://dj423fildxgac.cloudfront.net/fc6b316a-43b4-410f-8de6... except as a cargo ship^H^H cargo ekranoplan which could cross land as well as ocean?

what's the energy expenditure for an ekranoplan vs a boat per mile?

Whatever it is, it’s surely made up for in coolness-per-mile.

Like the imaginary giant cargo hovercraft from one of Arthur C Clarke’s stories.

Re: Mexico building rail rival as water shortages drain Panama Canal

#107

Post by loceng »

albert180 wrote: post #84
loceng wrote: post #80

Earlier quoted context omitted.

Maybe on the surface (pun intended) it appears stupidly expensive in comparison, but I bet if you actually put a value to all of the positives then the cost would at minimum be at par. With tunnels you can also go 3D, you could go 100 tunnels deep - stacked - increasing capacity on the same line as needed; something Elon points out as part of the traffic congestion problem is that cities went 3D (skyscrapers) but tra…

You build that route through nothing. There is no need for tunnels, and I don't see any positives, that you couldn't remediate much cheaper. For animal movement you can just build huge animal bridges every few hundred meters. Weather is rarely a problem for train operations, tunnels create also a whole lot of new "Negatives". You need evacuation systems, ventilation systems, maintenance etc...

I really would love to see an effort, perhaps best spearheaded by Boring Company themselves, to do a very thorough "feature matrix" of pros and cons and real-life current costs of things depending on the area, e.g. snow removal costs, how much building "huge animal bridges" that allows ecosystem to not be too disrupted, etc.

It's such a complex issue that a fully "complete" overview is necessary, that can be then dove into over weeks or months of time to first study its thoroughness to then be able to decide how accurate or credible it is, and add to or correct it if an incongruence or error or incomplete aspect found.

Re: Mexico building rail rival as water shortages drain Panama Canal

#108

Post by tomrod »

dave333 wrote: post #103
pxeboot wrote: post #74

Earlier quoted context omitted.

Pump it from where though? It would be easy to pump and reuse the water that already goes through the locks, except that it gets mixed with salt water, so putting it back in the lake would quickly contaminate it.

Pumping sea water to the top of the lock chain or maybe the lock next to the top would save a lot of fresh water but would slowly contaminate the lake unless there were some kind of double gate to prevent sea water used to fill the top lock leaking out when a ship enters the lock from the lake.

Solar desalination, perhaps?

Re: Mexico building rail rival as water shortages drain Panama Canal

#109

Post by profsummergig »

albert180 wrote: post #76
profsummergig wrote: post #30

Earlier quoted context omitted.

> what if we built say ten parallel railways 10 ft apart and moved cargo ships over the rails? Interesting concept. Never thought of it before. The India-Middle East-Europe Economic Corridor (IMEC) has a similar issue. Containers will be offloaded in UAE, then travel via rail through Saudi Arabia and Israel, and then reloaded on to ships in the Mediterranean for a short trip to Greece. Your idea is much more interest…

It's a dumb idea, we already have standardized cargo containers and the technology to load/unload them efficiently. Putting a ship on 10 Train Tracks will require the development of new technology and will make every bridge (weight allowance) and tunnel (the profile would need to be big enough for the whole ship) prohibitively expensive. With normal cargo trains, which are a very efficient and cheap way to transport…

Good reply. You're right, I hadn't thought about bridges / tunnels. Nor about the fact that the current system is basically "cheap off the shelf stuff".

This exchange has been a revelation in systems-design for me. The value one gets from adding another brain with a differing viewpoint.

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