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ENERGY INTERNATIONAL
February/March 2012 www.esb.ie/em
ESB Fisheries experiment with eel-deflection equipment
A COLLABORATIVE research project involving infrasound fish-deflection technology is taking place on the Ardnacrusha headrace canal at Clonlara.
Led by Dr. Damien Sonny, a consultant with Belgian company Profish Technology, the project is a collaboration between ESB Fisheries Conservation, NUI Galway and Hydro Quebec and aims to investigate the effectiveness of infrasound technology in diverting downstream migrating silver eels from potential hazards such as turbine passages. Infrasound is a high frequency sound wave, which may cause avoidance movements in downstream migrating silver eels.
Before the arrival of the Profish Technology and the Hydro Quebec research teams on site, ESB Fisheries Conservation obtained permission from Waterways Ireland to place the infrasound projectors into the headrace canal, which is also used as a navigation channel for leisure boats moving upstream and downstream through Ardnacrusha Hydro Station. A new jetty was erected from which boats and the equipment could be launched. Other equipment and large anchors were also placed within the headrace canal, onto which the infrasound projectors were attached. The anchor points within the water channel should withstand peak flow conditions.
The site at Clonlara was chosen because the channel’s 30m width allows for the optimum observation of eel movement by underwater cameras and the high flow rate alsoreplicates discharge conditions through typical hydro electric stations. The channel is also home to naturally-occurring eel.
“ESB Fisheries Conservation is confident that we can greatly contribute to the conservation of European eel stocks.
The project involves two infrasound projectors, placed in the headrace canal and deployed in a diagonal series at approximately 300 to the bank. The experiments will involve initial tests to determine optimal infrasound frequencies and the effective range by direct observation of eel behaviour using underwater cameras. The underwater cameras allow for direct observations to be made on changes in patterns of downstream migrating eel behaviour. It is hoped that avoidance of the infrasound field will be seen by observing eel movements to the other side of the headrace canal.
Welcoming the partnership with Profish Technology, NUIG and Hydro Quebec, Noel Greally, Manager of ESB Fisheries Conservation and Property & Asset Recovery said that such a partnership approach was the way forward in developing new methods of handling eel migration. “The Irish Eel Management Plan requires ESB to undertake trap and transport programmes annually, pending development of what are termed ‘engineered solutions’. In the past two years we have been involved in a project with French Hydro Power Company, EdF, in order to evaluate an eel migration peak technology. Hydro Quebec is the world’s largest hydro generator, with 59 hydro plants, including 12 stations of over 1,000 MW capacity, with the largest, Beauharnois Hydroelectric Plant, situated on the St. Lawrence River in Canada generating up to 1,900 MW and comprising of 38 turbines. By developing such partnerships, ESB Fisheries Conservation is confident that together we can develop improved eel migration protocols and greatly contribute to the conservation of European eel stocks.”
Electric and Magnetic Fields
SINCE THE 1970S, the alleged ill-health effects from powerline electric and magnetic fields (EMFs) have been an ongoing topic of debate. While the issue is most likely to arise during new overhead line projects, public concerns can also arise from existing electrical infrastructure.
Electric field levels are primarily affected by the voltage level of a circuit whereas magnetic field levels are primarily affected by the amount of current or load flowing through the circuit. The strength of both the electric and magnetic field decreases as the distance from the source increases. Electric fields will not travel through solid objects such as trees, walls or circuit insulation. Magnetic fields are more difficult to screen and will travel through solid objects such as walls and trees.
Studies on possible health effects have been reviewed by independent and authoritative international and national review panels of scientific experts. These studies have not established that power frequency electric and magnetic fields encountered in normal living and working conditions cause adverse health effects in humans.
As a responsible organisation, ESB regards the protection of health, safety and welfare of its staff and the general public as the top priority in all its activities and recognises the concerns that some members of the public have in relation to EMFs.
To address any individual concerns that are raised in relation to electric and magnetic fields, ESBI provides a service in measuring EMF levels on behalf of ESB Networks. Measurement sources often include lines, cables, substations - typically at transmission voltage levels but also occasionally at distribution voltages. These measurements are then compared to the European Union (EU) and the International Commission on Non-Ionising Radiation Protection (ICNIRP) guidelines on continuous exposure to 50Hz EMF. The reference levels in these guidelines for the general public are 5kV/m (kilo-Volts per metre) and 100ìT (micro-Tesla) for the electric and magnetic fields respectively.
For comparison purposes, the chart below shows typical EMF levels in the vicinity of overhead lines and typical levels that are present immediately adjacent to a range of everyday household electrical appliances. EMF levels from both ESB Plant and domestic appliances are considerably less than the EU and ICNIRP Guidelines. As indicated in the chart, it is often the case that higher levels of EMF can be found from everyday appliances within the home than from nearby ESB plant. For further information on EMF please contact either Robert.Arthur@esbi.ie or Bryan.Nunan@esbi.ie
