One note - they don’t pump water out and back into the locks from a neighboring storage. They flush the water. Each ship needs like 40 million gallons?
Maybe title should be insane wastes of water forces authorities…. :)
Maybe title should be insane wastes of water forces authorities…. :)
To start with, there is a difference in the water levels - and this can be put through a generator to generate electricity as the water flows from one lock to the other.
When the water has moved half way, the levels are equal. You can now use electricity to pump the rest of the way - and theoretically, assuming lossless pumps and generators, you use the same amount you generated earlier.
Unfortunately, low-head generators tend to be inefficient and expensive. Variable head generators are even harder to design to be efficient.
Water power efficency is about 80-90%
Big bucket high up is basically a battery. The question then becomes about the details of, like, using the power when the water gets pumped down (if you had two canals, you could probably time filling one with draining the other?). There's a lot of practical things to consider
Reminds me of this lesson in gravity: https://www.youtube.com/watch?v=vFUj6LH4FSI
My ship had two jet turbine engines that did 31 MW of propulsion, which was a small ship compared to most freighters, so energy wise it would be very efficient still.
40 M gallons is ~150 K*m^3. Modern bulk desalination turns seawater into potable fresh water at ~0.40 $/m^3, so only ~60 K$. The cost of filtering out any incidental saltwater mixing should be a tiny fraction of that cost.
Even at full desalination it would only constitute ~30% cost increase. Given the minimal amount of filtering that should be required for incidental mixture, it is hard to call that a great expense except in relation to rainwater.
And again, that is the cost of desalinating 100% seawater, not the proportionally cheaper cost of desalinating whatever single-digit to maybe low double-digit percent you would actually get from incidental mixture during reclamation.
[1] https://en.m.wikipedia.org/wiki/Panamax
[2] https://unctad.org/system/files/official-document/rmt2022_en...
I’ve always assumed the energy cost to pump the water would make it cost prohibitive, but I wonder how it compares to rerouting ships or moving containers over land.
This makes recovering water from the locks problematic, since you can't feed it seawater.
Raising water on the low side to the level on the high side simply requires joining the two sides together.
If sea level is their high side, I don't understand why they can't use this supply forever.
The obvious solution is a sea-level tunnel a hundred miles long. Probably cheap. ;)
Chinese company got concession to build decade ago, but didn't do anything and then went out of business.
The original excavation was done mostly dry and massive by any standards: 27kt of dynamite were used.
I'm also not a digger, but 26 meters of dredging over a 13km distance sounds crazy expensive. You would have to also widen the valley to prevent landslides into the canal.
The British locks depend on a source of water at the top of the canal. I watched a video recently about Canal Trust rebuilding lock reservoir. The water levels definitely can limit if locks and canals are usable.
The Panama Canal has a reservoir at the top, Gatan Lake, but the water is low. Sea level is never the high side, it is always the low side.
Some days we're just dumb, even if most days we're pretty smart.
Suez is (was? lets ignore geopolitics instead of physics for now) so successful because it's lock free (ha! tech joke on HN, I'm rocking this :D). The Panama canal was made by creating a massive artificial lake above "sea level" rather than digging a path down to sea level through mountains. Historically this worked, but alas enough corporations profit enough by offloading the costs of their industries onto everyone else as a form of socialism we call subsidized global warming.
- "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."