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Comment by kurthr | Hacker News Reader

Because the locks were built where they were over 100 years ago without the need for any pumps since there was an existing lake. The number of pumps, installation time, and power needed to run the locks (in both directions since the middle is at the top) would be huge. I could still happen, but take a decade to build out.

The vertical rise is about 26meters and there are 3 10meter locks (33mx300m in size) in each direction. 40 ships travel through each day (~3ksec per fill bidirectional) and each fill is ~1Billion liters or 250Million gallons in less than an hour. Lifting 1B liters through 30m would need 100MW to power 100% efficient pumps continuously for leakless locks. The solar/hydro power of rain is significant.

Also, everything in the lake would die once it was contaminated with sea water, and you would be contaminating the Pacific with Atlantic water, vice versa, or both.

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> you would be contaminating the Pacific with Atlantic water

Ahh that's what must be making the Drake Passage so angry.

The Cape of Good Hope will not allow this, the mixing of the seas should not be allowed.

That kind of cross tamination is a thing, goes also for ballast water of vessels. So yes, you'd want to minimalize that.

Drake Passage doesn't pose the same ecological risk, of course because the ecosystems are acclimatized to such a passage being there, but also because it's in the southern ocean surrounded by strong currents and cold water that mostly does not mix with the Atlantic and Pacific oceans. So many of the species at higher latitudes are essentially trapped on their respective side.

Just to add some the last piece of data: According to https://www.global-climatescope.org/markets/pa/, Electricity prices in Panama (in 2021) were $153/MWh, so the costs for each fill would be about $15,300

That sounds like a lot until you realize the largest ships are charged up to $150,000 for a transit.

A 10% price increase is nothing to scoff at, but it's not outlandish to deal with congestion...

Remember that it's not a single lock ships go through. If I understand correctly, ships are lifted in 3 locks and lowered in another 3. That would make it $45k+.

100MW sounds manageable if expensive.

But once you’re talking about anything near 100% efficient pumps, you can have generators too, and a lot of that water is, in principle, recoverable. A bigger issue may be doing any of this without bringing too much salt along with the upward-moving ships.

(Hmm. How about picking up the ships, sans water? I wonder if a way to do this safely could be engineered. Sounds quite challenging.)

Remember, that's 100% efficient continuous 100MW. Realistically, you're looking at 3-5x that for peak power. With the current 10m drop, the head is too low to have anything like an efficient generator. Even the full 86ft drop would be terribly inefficient at the flow rates required.

However, there are solutions to things like this called a "water slope" and one has been built (notably 100x smaller than needed for Panama) and they would (need to) be much quicker as well. Basically, they push a giant slug of water up hill. Notably, one could probably make this regenerative (and you could likely reuse most of the water). That's important since it would certainly be in the multiple GW of power, but it could push/pull (two moving locks up/dn) in <1000sec so traffic through the canal could be more than 5x higher. Of course it would require massive widening, completely new infrastructure (a new giant power plant), and completely new technology.

Here's video of one (and a link to the original) with an explanation. My point is not that this is easily doable, but if you're going to spend the many $10Bs of you might as well get more boats through.

https://youtu.be/N34QXyr-FY4?t=201

Would it be practical to integrate pumped hydroelectric energy storage into a canal lock mechanism? Pump water up to lower the water level; harness water flowing back down for electricity; and arrange the timing partly towards grid supply & demand.

Maybe dig a third reservoir adjacent to the lock mechanism, as a buffer between the two levels, to give you more flexibility with the timings.

[late edit]: Apparently this is in fact a thing, in some cases:

- "The hydraulic cylinders enable the water used by the locks to be pumped back. Up to 48,000 cubic metres of water are displaced in a single lockage operation. In periods of low discharge on the Meuse, the screws can pump back the water lost due to the passage of a ship through the lock to the upper canal reach. In normal periods of enough discharge at the Meuse, the screws are used to to generate green electricity from hydropower."

https://www.inlandnavigation.eu/power-of-water-and-wind/

> harness water flowing back down for electricity;

Too little head for good efficiency.

that's not bad at all, pumping stations with far greater requirements have been in operation for decades

https://en.wikipedia.org/wiki/Edmonston_Pumping_Plant

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