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Comment by tda | Hacker News Reader

Just did a little bit of a napkin calculation, how much energy would it cost to pump the entire flow of the Rhine 2m higher?

2m head difference, 20_000m3/s flow Due to head difference: 1000kg/m3 * 20_000m3/s * 9.8kgm/s2 * 2m = 392MW

Accelerating to 5m/s: 0.5 * 1000kg/m3 * 20_000m3/s * (5m/s)^2 = 250MW

That is at 100% efficiency. But knowing a modern container vessel has 60MW installed power, and a large coal powerplant (we should be closing those by the way) is about 1GW, this is in the order of magnitude of achievable. Biggest pumps I know of are 5MW (and for higher pressure/velocity, not low pressure/high flow) but if we really wanted to this could be solved

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You'd need to be able to deal with peak-flow to some extent.

Either he's already worked that in (20K cubic meters per second) or we can correct for it, the normal 'debiet' is about 600 cubic meters per second, the annual average is 2200, the peaks observed are about 12K.

Another big river to count with is the Waal, which does about 3/4 of that and then there are the Lek, the Maas and the Schelde, all of which are yet another doubling. So there would be a substantial amount of energy involved here.

I'd say the pump capacity and maintenance would be a bigger hurdle than the energy involved.

The largest pumps we have right now do about 250 cubic meters per second.

https://deafsluitdijk.nl/projecten/vergroten-waterafvoer/hoe...

I'd say that that is manageable.

The Rhine is 2,000 cubic meters per second, not 20,000.

From memory I believe the "Ruimte voor de rivieren" project was designed for peak discharges of around 15k m3/s, but could very well be wrong there. Normal discharge is much much lower. Just wanted to see if the extreme scenario is remotely feasible (which I would say it is, though it's pretty far out).

But if there is enough buffer capacity then of course you only have to dimension the pumps for longer term average high discharge, and not peak discharge.

Edit: Just found this: https://edepot.wur.nl/84989

1/1250 year Rhine discharge at Lobith is found to be and as higher discharges will cause major flooding upstream instead of reaching Lobith directly this should be about the max to expect. Such a peak discharge would be part of a high water period with discharges up to 15 consecutive days of >10.000m3/s, so you would need a pretty big buffer.

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