For an organisation which has been deaf to the protestations of the UK Microhydro Association and the British Hydro Power Association that its licensing procedure is inappropriate for hydro installations, I was pleasantly surprised that the two NRW people who came were willing to listen to the arguments I wanted to put forward.
I had prepared for them coming. I wanted to get across three things:
1. calculating abstraction volumes using the efficiency of the system at maximum power is wrong headed.
2. stipulating an annual maximum volume of abstraction is meaningless if the licence specifies the maximum instantaneous flow which can be taken.
3. the wording of their licence is internally inconsistent by stipulating in one section the maximum volumes to be extracted, yet in another section giving these same volumes as being minimum volumes.
To make the point about efficiency I gave them this graph which shows how efficiency falls off toward the upper end of power output. It is the same plot as I've posted before but in a different format and with additional data points added:
To make the point about having to adhere to an annual maximum volume, I pointed out that with the volume I've abstracted up to the end of January being 39,727 m³ and with two months still to go before the end of their "abstraction year" on March 31st, I was almost certainly going to breach the annual limit set at 49,982 m³, despite having kept within the limit of instantaneous flow set at 3 litres per sec.
Will anything come of it all ? - I'm not holding my breath, but on the day of the visit at least, it was nice to be reminded that there are, working within this bureaucratic quango, intelligent, approachable, rational, human beings.