W2W Top Trumps

 

W2W power flow starts getting interesting when applied to specific examples of WEC. I've chosen historical examples to avoid looking like I'm giving investment advice!  We're going to play 'Top Trumps' with three very different devices: the Wave Star arm (above), Pelamis, and the LIMPET OWC.  I learnt new and surprising things while preparing this blog post. At the end I compare the electrical generators and show how 'electrical power' is very different for these three devices.

 

Introducing W2W power flow diagrams

 

Wave to wire (W2W) power flow diagrams are interesting because they: 

• Provide a level playing field for comparing wave energy converters (WECs).
• Describe the physics of the power capture mechanism.
• Make it clear what subset of the process is being modelled, which is useful for model design and interpretation of results. This gives insights into important work such as the US Wave Energy Prize and WECCCOMP.
• Highlight challenges specific to wave energy, which can inform design.

Case study: perfect incubation for wind

  

A question we often hear asked is 'Why isn't wave energy commercial yet? Is there something fundamentally wrong with it?' The question is both really interesting, and a pain to get asked: there is no simple answer, everyone has a different take on this, and often the person asking just wants a simple thumbs up or down. 

Wind energy can be a useful analogy, especially for those of us ancient enough to have watched as it 'grew up', and to remember the same types of doubts directed at it. There are several techno-economic ideas (see Glossary for definitions) that are familiar when applied to wind energy, which we can then use as lenses for looking closer at wave energy.

Where techno- meets -economics

 

Annual Energy Production. Where techno- meets -economics.  

But what are the devilish details along the way to coming up with one number that describes the power capture of a wave energy converter? And how does this fit into a conversation about commercial development? And what red flags 🚩🚩🚩should we be on the lookout for when trying to make sense of published numbers on wave energy converter performance?