Prototyping a series of bi-directional horizontal axis tidal turbines for optimum energy conversion

► A new series of bi-directional HATT rotors was developed. ► A generic wind/tidal turbine rotor design and optimization procedure was developed. ► An unsteady, time-domain, and efficient panel method was developed and validated. ► The code finished over 15,000 runs in 3 months while a RANS CFD will take 50 years. ► A 53% power efficiency was achieved to produce extra energy of 1230 MW h/year.