Comparative tank test challenges: ...... Part I ...... systemic errors and bias

A USA funding body (Wind and Water Power Technologies Office) recently called for advice on an innovation prize challenge for WECs. The proposed approach was tank-testing of ten short-listed concepts. I was very encouraged by this proposal, and this got me thinking about the practical challenges of comparing ten very different concepts using tank tests. There is a risk that the concept which does best in the tank may not be the concept which does best at sea. The reasons for this include:

• scale and conditions insufficient to identify full-scale sea-trial problems
• systemic tank testing errors
• systemic bias due to choice of test program
• systemic bias due to practical restrictions on test program
• practical difficulties associated with direct comparison of different types of device
• bias due to non-blind testing

Beautiful and wild

Health warning: do not look at this painting too long if you suffer from sea-sickness. As you focus your eyes on the quilt of waves on the horizon, you stomach will eventually get dragged down into the wave trough in the lower left hand corner. Yes, the sea is beautiful, but it is not tame. The sea's power leaves us feeling small; it even dictates our horizons.

In a nutshell: Peaks and Troughs (Yemm)

The Peaks and troughs of wave energy is a treasure trove of gems awaiting discovery. There are associated papers, but there are also audio recordings of all the talks. Richard Yemm's (Pelamis) talk is particularly good. He shared his experience of "the coal-face" (oh dear), and gave his candid opinion of mistakes Pelamis had made, as well as things that they felt they'd got right. It was clear that the pitfalls experienced by Pelamis await others following in their path, and his talk was peppered with advice for other developers.

Design challenges - Oscillating Wave Surge Converters

In this article I outline my thoughts on the design challenges and opportunities associated with WECs known as 'Oscillating Wave Surge Converters'. As discussed previously, this term is used to describe seabed-mounted pitching flaps.