Guest editorial

Significant resources are currently being spent on establishing offshore renewable energy systems such as wind and wave energy with recent trends to move sites to increased distances from shore and to greater water depths to exploit more energetic climatic conditions. The wind power industry has grown considerably over the past 15 years, but other offshore technologies such as wave and tidal energy have also emerged. With this trend to moving further offshore, technological and logistical challenges have emerged. Currently, the relative immaturity of energy conversion technologies and operational uncertainties make the cost of energy high compared to other more convetional enerty souces. Maintaining existing assets and developing strategies for new assets become a challenge and have a key empact on downtime and lost revenue. Hight quality research helps to ensure that offshore renewable energy becomes and economically viable alternative to conventional energy sources.