TIDAL ENERGY PROVES ITSELF

Marine Current Turbines reveals details of SeaGen's Operating Performance
3 November 2009 (Marine Current Turbines)

"…Peter Fraenkel, Technical Director and co-founder of Marine Current Turbines, the [designer/developer of] SeaGen, the world’s only commercial scale tidal turbine [said] SeaGen is running at full power and fully automatically exactly as planned…driven by a wall of water 27m deep, similar to the height of the Tower of London, that surges back and forth with every tide through the Strangford Narrows in Northern Ireland at speeds of up to 10 miles per hour…

"SeaGen has already delivered over 350 MWh into the Northern Irish electricity grid. The twin generators typically produce an average of 5MWh of electricity during the 6¼ hours of each ebb and each flood tide. This is enough energy to meet the average electricity needs for 1500 UK homes."

SeaGen in a strong flow, wake visible. Photo from Dr D Erwin. (click to enlarge)

"The SeaGen turbine, with its twin 16m diameter rotors, is officially accredited to OFGEM as a “UK power station”, the first tidal power system to secure this. It is earning revenue from the sale of the power that is being generated and it also earns ROCs, the Renewable Obligation Certificates that are awarded for clean renewable generation…

"…SeaGen has been operational for most of this year…[In] September…consent was given to operate it without…environmental scientists (marine mammal observers) on board and onshore. This was an initial requirement under the licensing arrangements to ensure that SeaGen did not adversely affect the marine mammals that are a protected feature of the local waters and restricted SeaGen’s uninterrupted running. However extensive experience gained so far suggests the seals and porpoises are not at any significant risk and as a result SeaGen is now permitted to operate unattended and by remote control…"

Typical output. Explanation below. (click to enlarge)

"…[A]n operator onshore will continue to monitor a sonar image of the passing flow which can show up any seal that ventures too close to the rotors, and the operator has the facility to stop the machine. As confidence and the body of evidence grows, it is expected that full 24 hour running will be permitted in the near future…

"…SeaGen’s output on a typical tide (roughly halfway between Neaps and Springs) [is graphed above]. The black trace shows the speed of the current in m/s (on the right hand scale). The red trace from the instrumentation is the corresponding response from SeaGen, showing the power and shows how it ramps up after slack tide to 1200kW at which point the control system holds the power constant. The dip in the trace was a deliberate shut-down using the pitch control system to stop the rotor safely and it shows how the system then restarted and went back to full power. This illustrates the controllability of the turbines, a vital requirement for any power plant…The area under the red trace is the [5.2MWh of] energy delivered [on that tide]…"