Energies 2013, 6, 1497-1526; doi:10.3390/en6031497 OPEN ACCESS energies ISSN 1996-1073 www.mdpi.com/journal/energies Review 2002–2012: 10 Years of Research Progress in Horizontal-Axis Marine Current Turbines Kai-Wern Ng 1, Wei-Haur Lam 1,* and Khai-Ching Ng 2 1 Department of Civil Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia; E-Mail:
[email protected] 2 Center for Advanced Computational Engineering (CACE), Department of Mechanical Engineering, Universiti Tenaga Nasional, Km. 7, Jalan IKRAM-UNITEN, 43000 Kajang, Selangor Darul Ehsan, Malaysia; E-Mail:
[email protected] * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +603-7967-7675; Fax: +603-7967-5318. Received: 30 November 2012; in revised form: 13 February 2013 / Accepted: 26 February 2013 / Published: 6 March 2013 Abstract: Research in marine current energy, including tidal and ocean currents, has undergone significant growth in the past decade. The horizontal-axis marine current turbine is one of the machines used to harness marine current energy, which appears to be the most technologically and economically viable one at this stage. A number of large-scale marine current turbines rated at more than 1 MW have been deployed around the World. Parallel to the development of industry, academic research on horizontal-axis marine current turbines has also shown positive growth. This paper reviews previous research on horizontal-axis marine current turbines and provides a concise overview for future researchers who might be interested in horizontal-axis marine current turbines. The review covers several main aspects, such as: energy assessment, turbine design, wakes, generators, novel modifications and environmental impact.