Robin wrote:
On 17/11/2019 10:07, wrote:
On Sun, 17 Nov 2019 09:40:54 +0000
Graeme Wall wrote:
On 17/11/2019 09:04, wrote:
On Sat, 16 Nov 2019 14:48:05 +0000
Recliner wrote:

https://www.flickr.com/photos/reclin...-friend/lightb

ox/

I wonder why the water tunnels are so deep. You'd think when pumping water
around you'd want them to be as shallow as possible since water is heavy
stuff
and requires huge amounts of energy to pump back uphill.


The problem with that diagram is that it shows depth below ground level,
not sea level (or river level in this case), so it gives a distorted
view of the actual depths.

One possible reason for a deep water tunnel is to give it a straight run
so you don't have to keep pumping water uphill at intermediate points on
the route.

Makes sense. Even so, I dread to think how much electricity the pumping must
require. Probably a small power stations worth.


The Thames Tideway's annual consumption was reckoned to be about 9,000
MWh. A handful of wind turbines cover that (leaving aide the usual
intermittency issue).

I assume the Thames Tideway pumping needs are also intermittent, as it's
essentially an overflow storm drain to intercept polluted water and sewage
that would otherwise flow into the river. For much of the time, it'll
presumably be empty, but will fill up after heavy rain, and need pumping
out?