Theory 099/Energy & Environment /Marine energy
Tidal Power Needs Resonance
Tidal resource is estimated from range. The basin's own period may amplify it.
The tidal energy available in a basin is set by how close its natural period is to the tidal forcing period rather than by tidal range, so a basin with a modest range near resonance can out-yield a larger one far from it.
01The evidence
Tidal ranges vary enormously between basins with similar ocean forcing, and the amplification is attributed to resonance.
02The tension
Resource assessments use observed range, which measures the result and does not predict what a basin could deliver if modified.
03The mechanism
A basin responds to tidal forcing as an oscillator. When its natural period matches the forcing period, the response is amplified, and small changes in geometry can move it toward or away from resonance.
That makes the period ratio the determinant, and predicts that modest-range basins near resonance have more extractable energy than their range suggests.
04What this is not
Range assessments measure the response. This measures the proximity to resonance, which predicts sensitivity to geometry.
05Predictions
- P1Extractable energy should track the period ratio.
- P2Near-resonant basins should out-yield larger ones.
- P3Geometry changes should shift the resource.
06Refutation
Energy tracking range at controlled period ratio would restore range assessment.
07What it changes
It would change tidal site selection.