Toilet Turbines?

it had to be under pressure to begin with unless they're tapping a river going several ft/m, energy is rarely free sounds like a, rob Peter to pay Paul thing

Well, a city with many hills might have to provide water to water towers on the highest hills. From there it flows by gravity to houses nearby and it can also flow to other parts of the city that are lower down. Many cities must install pressure regulators to houses 1000 feet lower do not get water at 500 psi or so from the potential energy of the original height. Many high towers also have the same problem, but they usually operate cisterns every few floors to deal with a number of floors.

This is a method to not use pressure regulators - which waste energy, instead they lower the head by removing energy. Same with sewage going down hill, to avoid it coming to the water treatment 1000 feet lower at ~500 psi, they drain potential energy by these turbines.

Sounded like a stupid idea at first, but you might be on to something.

Did you mean "shit" idea?

I believe civil engineers have to take a fluid dynamics course called "Inhomogeneous Flow" that might cover this case.

I can't believe nobody's made a crack about "when the s*** hits the fan"!

Only if i don't have to repair them.

Sub the maintenance out to Blackwater.

Good play on words there.

I wonder how the flotsam (or is it jetsam in the case of this purposely dumped cargo) in the sewage would affect the turbine, especially if it gets paper wrapped around it.

It would likely slow it down by at least a turd, and could result in a total blockage as other debris piles up behind.

LOL!!

Maybe sharp leading edges will help?

whenever water pass through a turbine won't there be any pressure drop. What type of generator is used where flow rate varies constantly.

The input or output is processed to provide usable power. A constant speed drive can accept variable speed and produce constant speed mechanically. A generator can provide AC which is converted to DC and then to AC, independent of speed. The alternator in a car produces AC which is converted to usable DC, independent of speed.

Is the same technology used in wind driven generators too. In domestic smaller units won't it be very expensive?.

Seems like a pretty good sells pitch, never mind the fact that Portland is located next to the largest river west of the Mississippi. Wouldn't it be more economical to plant vertical turbines in the Columbia river? And as secondary benefit, the top of the generator housing would offer more nesting perches for the Bald Eagles and Ospreys that live around the river.

It's called Portland because it is a shipping port. Not a good place for underwater anything except the hull of a shipping vessel. There are already numerous dams and generators installed further up river, one of them in BC near my dad's place, but putting turbines in the shipping channel at the mouth of the river would be a big problem. Anchors, hulls, props and lost cargo containers would all be a problem for the turbines.

Yeah, but just imagine the kinetic energy content of such heavy objects....

which could be captured by a fleet of Kastrupsky energy barges.

I wasn't meaning to install turbines in the shipping channels. That river is wide enough to install turbines 10 yards off shore. And with all the dams up stream, the water flow is pretty consistent and strong enough that I won't go swimming in it.

The only conflict might be is with the damn gill netters. But then that might get them off the river too! And that would be a good thing too.