Tethered Tidal Kite Energy Converter

Tidal Flow

Current speed 1.2 m/s

Kite

Glide ratio L/D 9.0

Tether length 18 m

Onboard Turbine

Rotor diameter 1.2 m

Live Readouts

Kite speed (through water)

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Flow at rotor

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Power output

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Speed multiplier ×v_c

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vs. fixed seabed turbine, same rotor

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How it works

A tethered kite anchored to the seabed flies a fast figure-eight ("crosswind") loop through the tidal stream. Because the kite is free to move, it doesn't just sample the current speed v_c — it accelerates until drag balances the tether tension, reaching a much higher water-relative speed set by its lift-to-drag ratio:

v_kite ≈ (L/D) · v_c        (crosswind kiting speed, Loyd's law)
v_rel  = v_kite  (flow seen by the onboard rotor, kite-relative)
P = Cp · ½ · ρ_water · A · v_rel³ ,  Cp ≈ 0.4, ρ_water ≈ 1025 kg/m³

Because power depends on the cube of the kite's own speed rather than the current's, a modest current (~1–1.5 m/s — too slow for an economical fixed turbine) can still drive a small onboard rotor at 10–20 m/s of relative flow once L/D is high enough, extracting far more energy per unit of blade area than a turbine bolted to the seabed at the raw current speed. This is the operating principle behind real deep-water tidal kites such as Minesto's "Deep Green".

Current speed — the ambient tidal flow the kite flies through.
Glide ratio L/D — how efficiently the kite's wing converts drag into cross-flow speed; higher L/D means a faster, tighter figure-eight and a steeper power curve.
Tether length — sets the physical radius of the flight path (visual + orbital period), anchored at the seabed pylon.
Rotor diameter — swept area of the small turbine riding on the kite; power scales with area but the cubic speed term still dominates.

Kite + tether Current flow Rotor thrust axis

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