Electric fish barriers NEPTUN

1.“Informational” electric field - electric energy absorbed to scare not to stun the fish. 2.Random alterations – prevent adaptation to constant electric field. 3.Ease of installation 4.Size flexibility 5.Resilience and robustness 5.Resistance to low temperature (icing). 6.Low energy consumption (solar panels for small barriers) 7.Low maintenance costs. Key Design Features

Features That Set Neptun Apart Non-linear distribution of the electric field in water, contrast to classical barriers where the electric field intensity in the area between the electrodes is constant regardless of fish location (next slide). Intensity of the electric field  positive electrodes - close to zero  negative electrodes maximum. Adjustable DC pulse parameters: amplitude, pulse duration, intervals between the pulses number of pulses in a packet.

NEPTUN technology

U = E x L where: U – voltage accumulating on the fish’s body E – current intensity L – fish’s length 1 – average gradient E at all sections of the electric barrier (U1) 2 - average gradient E at all sections of the electric-electronic barrier (U2) 3 – direction of fish movement B=D classic electric barrier C>A NEPTUN technology Gradient of the electric field : classic electric barrier vs NEPTUN technology => The closer the fish the stronger the field !!

U = E x L where: U – voltage accumulating on the fish’s body E – current intensity L – fish’s length 1 – average gradient E at all sections of the electric barrier (U1) 2 - average gradient E at all sections of the electric-electronic barrier (U2) 3 – direction of fish movement A>B>C classic electric barrier A<B<C NEPTUN technology Gradient of the electric field : classic electric barrier vs NEPTUN technology => Size matters but distance matters more!! Selectivity possible.

Simplified block diagram of the NEPTUN device

Example of the single electrode Electrodes are attached to a line along the bottom (next slide) and have floats on top to hold them in vertical position Electrodes are flexible and allow passage of debris, etc. Ideally, a concrete floor is used to anchor the electrodes, but not necessarily

Rope to which the electrodes are attached is mounted to the bottom

Pictorial diagram of electrode spacing

Lab test

The electronic equipment of the control and power supply systems – open switchbox, the weir in Krzywaniec, Bóbr River.

Technical parameters length : 93 m length of a single electrode: 2.2 m for electrodes with positive and negative polarisation electrodes: acid resistant steel A4 electrodes mounting : anchored to a concrete block at the bottom of the reservoir power supply for the control and power supply system: 3-phase, through a separate transformer, (1-phase possible) average power intake : KWh

to Hydropower Plant Electrodes Negative polarization (-) Electrodes Positive polarization (+) Electronics Installation on the weir in Krzywaniec, Bóbr River Installation on the weir in Krzywaniec, Bóbr River.

View of marker buoys of some negative electrodes

Rzeszów

Szczerców

Acoustical monitoring of fish at an electric barrier –NEPTUN EY 500 split beam echo-sounder with the transducer directed horizontally. Krzywaniec reservoir / Dychow complex hydraulic engineering, on the river Bobr Stationary measurements powered and not powered (next two slides)

Barrier off… presence of fish between electrodes detected by hi-res sonar Fish are everywhere; N=283, scanned for 4 minutes

Barrier on for 20 min presence of fish between electrodes detected by hi-res sonar Few fish attempting to cross the field; N=10; scanned for 4 minutes

Minimum Technical parameters required for design Design criteria: Site map showing intake, outlet of turbines, fish-passes; Depth and electric conductivity of water Substrate Mean cross sectional velocity (no greater than 0.5 m/s) Available power supply (1- or 3-phase)

Neptun Benefits Increasing field intensity Electric field depth-independent Electric field can be depth-dependent Low power consumption (solar for small barriers) Low operation and maintenance costs Safer Electricity does not disperse into the ground No depth limitation …

Neptun Benefits No debris interference Does not affect navigation Safety and operation logging Remote control Can be installed anywhere (new or retrofit) Many applications Low purchase and installation costs More humane