Much of the growth in the tidal turbine industry is concentrated in energetic current
sites within current magnitudes exceeding 2m/s. Less energetic sites with U∞ < 2m/s
are not tapped since there is no perceived economic benefit.
This thesis explores the benefits of designing higher tip-speed ratio (TSR) rotors
that operate in less energetic currents with the hypothesis that such rotors are can
increase the viability of tidal turbines in less energetic sites. A parametric blade design
methodology is developed to push the optimal TSR of rotors towards higher values. The
performance of the blades is simulated using a BEM code with wave-current interaction.
The blade designs are then evaluated according to three objectives: power, TSR, and
thrust. A general cost model is also developed to evaluate the economic feasibility of
the resulting blade designs.
High-TSR rotors were found to reduce the cost associated with the generator, which
then drives other cost components of a turbine although this is only significant up to
a threshold rotational speed of 50RPM. Higher TSR rotors have better LCOE values
but utility scale feasibility is yet to be seen. The lowest LCOE value of the resulting
turbine with a high-TSR rotor is at 0.6 EUR/kWh which is still higher than the current
strike price of current tidal stream energy projects. However, these turbines may still
be beneficial for off-grid sites that rely on unsustainable diesel-fired generation.
While cost is an issue, high-TSR rotors overcome the issues when operating in less
energetic currents - load variability as result of low magnitude current velocities that
are more susceptible to wave-induced variations. High-TSR rotors lessen the variation
in load in addition to reducing the load due to lower torque and thrust loads since
high-TSR rotors tend to have low solidity.
| Date of Award | 27 Mar 2024 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Supervisor | Cameron Johnstone (Supervisor) & Nick Kelly (Supervisor) |
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