Brow Grains Dyke

Pre install summary:

This site is an old mill site with a lot of existing infrastructure - and most of it is intact. The owners are keen to install a micro hydro generator to power their house and sell excess to the grid. Its also an unusual case as the entire infrastructure and length of depleted waterway is owned by one person, so there are (hopefully) not so many issues with multiple ownership. Also as the depleted stretch of water is between two 3 metre high weirs the should be a relatively straightforward discussion with the Environment Agency as there are no issue with migratory fish.

Water enters the mill pond goit next to the first of the weirs and travels down the mill pond leat (about 20 metres) to the mill pond. This channel isn't open at the moment to prevent the mill pond filling up and overflowing. However to get the leat opened up seems to be a straightforward operation (with a fair amount of digging - though it should be possible to flush out much of this via the mill pond overflow sluice gate.

The pond itself is quite large (around 0.8 acre) and can be filled to a (max) level of around 1 metre. The gross head from the mill pond to the potential turbine site is just over 10 metres - however when equipment siting and civil works are complete this will be reduced by around 25%.

The flow rate (as with all pennine streams and rivers) is extremely variable - besides the natural peaks and troughs, there is a reservoir at the top of the watercourse that releases a compensation flow for most of the year, but when the reservoir is full this is quite considerably increased.

The potential power output for this site is estimated to be between 1kWp and 4kWp.

The flow duration curve for the site is below - the blue line is the natural flow, the red the actual flow. For some of the year (not sure how long exactly - I'm waiting to find this out) the flow is largely a 30 litres a second compensation flow - much of the water being diverted to Blackmoorfoot reservoir.

Flow duration curve at the weir on Brow Grains Dike

New Information Oct 2014 - post install

The system has been installed now using 3 Powerspout Turgos and an Enasolar 2 Kw inverter. The site has very variable flows (it shares a catchment with a large reservoir, so much of the time the only flow available is the compensation flow).

During the process a bigger system was initially proposed, but it didn't stack up financially due to the restricted flow for much of the year.

The site owner has largely installed the system - a coanda screen (from Dulas), 180mm PE pipe, a concrete based turbine house and 3 turgo turbines.

A really good install - and great to see that the effort and energy of the site owners and installer has paid off - it's taken a long time and required quite a bit on engineering along the way. Not to mention several surveys (crayfish principally) and extensive negotiation for permissions.

 

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