Hydro Power in Sewage Works

[sow]

We are looking into the feasibility of installing a small hydro electric unit downstream of a sewage inlet works.

The system will be around 250kW. It shall be a Kaplan type reaction turbine.

Although the sewage inlet works has screens(6mm 2 dimensions)and grit removal, I still have concerns regarding ragging up and grit erosion and build up in the turbine.

Does any one know of a similar installation, or have they considered one?

Thanks

Sow

 

[BobPE]

You have some very valid concerns...I just can't imagine the O&M on a facility like this...I have worked on several facilities that harness raw water from canals and that is in itself tough to handle and labor intensive. Sewage...I can't imagine the grit being anywhere near friendly to accomodate. Ragging..well, all this would have to be addressed most likely by an elaborate upgrade to the pre treatment to the headworks to make it work with any degree of consistency.

I am assuming the the influent tot he headworks in from a force main or some type of system under pressure? Even then, I can't see there being that much energy available at the headworks to make this feasible. What are your flows like before I go to far assuming? And more importantly, what are your ideas and thoughts beyond the obvious you stated? What would you use the power for, what is your target ROI?

Even with all that, it's still fun to think about...

BobPE

 

[Bbird]

If the source point of the sewerage has a sufficient head above the discharge point there is nothing technically against the power recovery by dropping in a Kaplan unit.

The erosion of the runner is obviously an issue but at 250kW the associated equipment and maintenance work may not be as viable as it looks.

I have seen several energy recovery systems for the coooling water circuits of power plants, using both seawater and river water, but for reasons they all came to a halt after additional investments for renewing the components were either ignored or could not be justified.

Even at 250kw the civil and mechanical work arranagement have to allow for a outage of the kaplan and a bypass is therefore necessary with a system to dissipate the unwanted 250kw of energy. The capital cost of the transmission system, switch gears and operation and control for such a small unit have yet to be proven viable.

The erosion of the runner, which can be replaced easily, is the least of the above worries.