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Comment by jedberg | Hacker News Reader

I wonder at what point it makes economic sense to "solve" the freshwater problem in Panama with new infrastructure. My understanding is that they lose a lot of water because it has to get flushed out to sea.

Is there an engineering solution to recycling more of the water and flushing less of it to sea?

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The locks are all gravity powered. They certainly could operate the locks by pumping uphill instead of releasing downhill, and thus lose almost no water. I expect the expense of this makes it a non-starter.

>I expect the expense of this makes it a non-starter.

I am seeing numbers that it costs anywhere between $100k-400k per trip to go through the canal, with some tens of ships per day.

So of course, this highly profitable venture would dedicate basically nothing to improving the infrastructure until it became a tire fire.

You use big pumps to fill the lock from the low side instead of just opening a valve or the doors slightly. This would then increase the salinity on the lake side and cause whatever problems that would cause.

What I'm saying is, is there an infrastructure solution that doesn't increase the salinity in the lake? Like can we use gravity up to the last lock, but then pump all the fresh water out back to the lake and then pump seawater into the chamber after it's empty? Or something crazy like that.

The new set of locks in the Panama canal use "water-saving basins" to reduce the amount of water lost for each cycle of the locks. https://en.wikipedia.org/wiki/Panama_Canal_expansion_project...

I guess in principle something like this could also be retrofitted to the existing locks.

It feels like any form of recycling water would mean pumping water back uphill, which is energy-intensive, at least relative to the current model of "just pull water from Lake Gatú and assume it never runs out".

But using less water in the first place, I'm curious what approaches might exist.

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