EA/NRW compensation flow and OFGEM Interpretation

Discussion on technical issues surrounding medium head (typically from 10m to 100m water pressure) hydro schemes.
huw scourfield
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Joined: Fri Jan 13, 2017 11:16 am

EA/NRW compensation flow and OFGEM Interpretation

Postby huw scourfield » Tue May 30, 2017 10:43 am

I would like members thoughts on OFGEMs interpretation of a compensation turbine, where the turbine is sized to provide all of the downstream flow; essentially how much over the statutory compensation flow should the turbine be rated (and allowed) to flow? The point being of course, if the turbine flows exactly the compensation flow and no more, there is no "buffer" to a restriction/weeds etc reducing the flow and NRW (in our case) prosecuting on grounds of failing compensation.
I would expect that something like 10% would seem sensible - after all there will always be some %age allowance for the operators and NRW flow measuring equipment - it seems however in this instance OFGEM might want to force us as low as possible. Oddly enough as the site is an impounding reservoir on occasions very tight on capacity Vs demand we have are in agreement with OFGEM to some extent - it's just that we don't have a figure for it (well we do but OFGEM seem to think at 10% it's a bit high).
Experience/thoughts please?
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Re: EA/NRW compensation flow and OFGEM Interpretation

Postby MorHydro » Sun Jun 11, 2017 2:12 pm

Surely the problem is not the turbine size but the blocking of the compensation arrangements. That happens on many sites and frequent inspection and screen cleaning may be required. It is really about the dimensions of the screen that protects the compensation flow.

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