Measurement of noise from Islay Gully wave energy device

This report describes investigations to identify the principal noise sources, to provide information for carrying out environmental assessments for similar devices at other sites, and to establish any requirement for noise reduction. Measurements were made over a range of operating conditions. The device produces high levels of noise of a distinctive character. It is estimated that the noise is of the order of 30 dB higher than that of a wind turbine of comparable output. Although a wave device would generally be located in a remote area noise may be a major factor in determining the acceptability of this type of device. The principal source is aerodynamic noise produced by the two-stage Wells turbine, emitted from the open inlet/exhaust duct. It may be possible to achieve limited noise reduction by changes to the configuration of the turbine, to optimise aerodynamic and acoustic performance. However, the turbine is aerodynamically novel, and an extensive research and development programme might be required to perform such optimisation. It is considered that some improvements could be developed as a result of design analysis, theoretical modelling, and more detailed analysis of noise and performance data from the current device. If further applications are planned, specific control measures such as an inlet/exhaust attenuator may be required. It is recommended that the design of such measures should be progressed to ensure that the required degree of noise reduction can practicably be achieved. (author)