Noise project completed
Eight builders and operators of German offshore wind farms have presented the final report on the ESRa (Evaluation of Pile Driving Noise Mitigation Systems) noise mitigation project. The research project tested new noise reduction systems designed to mitigate the spread of ramming noise and protect porpoises during the construction and installation of offshore wind farms. Bard Engineering, DONG Energy, EnBW Erneuerbare Energien, E.ON Climate Renewables, EWE Energie, RWE Innogy, Stadtwerke Munchen and Vattenfall participated in the ESRa project. Each of the noise mitigation systems, manufactured as prototypes, withstood the harsh conditions at sea and demonstrated a noise mitigating effect. When corrected for site specific effects, the mitigation effect totalled up to nine decibels in the relevant range. This brought the noise level much closer to the noise emission limit of 160 decibels at a distance of 750 metres around the source of the noise. The report recommends more research and development work in order to meet the limit reliably in future.
Background noise study
Barcelona firm ICR (Ingenieria para el Control del Ruido) has presented the initial phase of an investigation into the characterisation of exterior background noise. The programme is titled Sound Meteorological Environmental Correlation, or SOME-ECO. In collaboration with AEMET (the Spanish meteorological agency), SOME-ECO looks to evaluate external background noise by correlating it with the meteorological variables in a place with specific characteristics. The one-year study reformulates the current methods for background noise measurement and provides representative data for, ICR says, more realistic measurements and forecasts of background noise. SOME-ECO analyses atmospheric pressure, temperature, wind speed, humidity and thermal gradient with altitude, showing the evolution of each variable over time and examining how each contributes to background noise. ICR says SOME-ECO will allow wind farm builders and operators to accurately evaluate the viability of development sites.
Mitsubishi Power Systems Europe, SSE, Technip Offshore Wind and Wood Group Renewables have announced the start of the £33 million (around €42 million) Efficient Offshore Wind Programme (EOWP). Set up to overcome challenges in the offshore wind industry and create over jobs in the UK’s energy sector, EOWP is planned to investigate many elements of offshore wind farm design, with the overall objective of improving the viability of offshore wind. By 2015, the EOWP is expected to complete a number of projects focused on efficiency and cost-effectiveness in offshore wind technology.
New ‘flat-pack’ turbine
Renewable energy firm McCamley has designed a new ‘flat-pack’ vertical axis turbine that overcomes many of the issues associated with wind turbines installed in cities and towns, the company said. The turbine requires no supporting mast and can be retrofitted to any roof. The company said its scalable design could one day even incorporate offices or residential buildings into the design. McCamley claims its vertical-axis model is able to work efficiently in the turbulent and variable wind speeds associated with urban environments. In addition, its ‘self-starting’ technology means it does not need power from the grid to restart if wind speed drops below a certain level. Field trials have shown it can start generating at low wind speeds of 1.8 metres per second. A 1 kW prototype is being tested at Keele University in North Staffordshire, UK. The company says it plans to realise plans for a 12 kW model.
Tunisian company Saphon has developed a bladeless wind turbine, inspired by sailboat design. The turbine’s blades are replaced by a sail-shaped body, while both hub and gearbox are removed. What the company calls its Zero-Blade Technology ‘is completely different compared to the current three-blade rotational wind turbines,’ said Hassine Labaied, Saphon’s chief executive. Instead of blades, a sail-shaped body follows a ‘knot path’ of back-and-forth movement with the wind current, converting the majority of its kinetic energy into mechanical energy to move pistons. This movement creates hydraulic pressure that can either be stored in a hydraulic accumulator or converted to electricity through a hydraulic motor and generator. Because of the device’s aerodynamic shape, says Labaied, the drag force becomes the system’s driving force while the lift force becomes almost nil. Saphon says its technology is capable of overcoming the ‘Betz limit’, or the maximum possible energy that can be derived from a wind turbine. (German wind technology pioneer Albert Betz stated that no turbine can capture more than 59.3% of the wind’s kinetic energy.) The company has tested a 300 W – 500 W prototype with a diameter of 120 cm.