To the reader:

  This Introduction provides an overview of my invention: a special marine hydrokinetic turbine that always spins in one continuous direction even when subjected to bi-directional air or tidal flows.  The turbine is uncomplicated and straightforward; it's all about directing fluids in an elegant and creative way to do useful work. The only moving parts are the two rotors.  There are one-way bearings sealed within the hubs of each rotor.  These are affordable, off-the-shelf bearings.  Simplicity of design is an absolute necessity for an ocean-based device to be successful and cost-efficient. My turbine is designed for long-term survivability.  It is robust and will last for decades with minimal maintenance.  No wave energy turbine components are immersed in sea water. 

  Engineering studies have been completed at three universities.  The first study at Oregon State University (OSU) validated the Hanna design as a self-rectifying turbine using bi-directional air flows.  Another study from France's Paris Tech, compared the Hanna Turbine with the Wells and Impulse Turbines using two advanced predictive methodologies: numerical modelling and 2D monodimensional analysis.  In this study, the Hanna design showed better efficiency metrics than the Wells and Impulse Turbines.  Read the Master's Thesis' Abstract by Théo Delecour below.  This is the Abstract only.  For permission to read the entire Master's Thesis, please contact John Hanna directly.

  The third study was done at the Dubai campus of Heriot-Watt University, one of Scotland's oldest institutions of higher learning.  This CFD study also showed favorable performance over existing self-rectifying wave energy turbines in today's global market.  Read the Master's Thesis by Joe Ninan Sunil below. 

   The reader is encouraged to do an assiduous review of existing wave energy turbines such as the pioneering but inefficient Wells Turbine. Your own informed assessment can then be made. Upon carefully reading the following material, you will understand that this design is the most efficient, versatile and adaptive of all existing wave energy turbines.  Importantly, the device is not only a wave energy turbine; it can also be used as a bi-directional tidal turbine!  To view a video of the Hanna Turbine in the Tidal Energy configuration, go to: and

  I am an inventor, not a developer.  Therefore, to assure the responsible development of this useful and versatile technology, my patent and IP is being offered for acquisition to a qualified developer, manufacturer or university.


  John Clark Hanna

About J. C. Hanna: Click HERE

Hanna Turbine Tech. Report.  (Master's Abstract by Théo Delecour )

Master's Dissertation  (Master's dissertation by Joe Ninan Sunil)

   OVERVIEW: To improve the effectiveness of wave energy harvesting and double the electrical output of existing wave energy conversion devices, the technology needs a more efficient air turbine: The Hanna Turbine offers a powerful unidirectional turbine designed to operate seamlessly in the bi-directional air flow environment common to all Oscillating Water/Air Column systems.

 Wave Energy Conversion (WEC) is an emerging technology sector that harvests energy from ocean waves. One sub-class of WEC technology uses special turbines to generate electricity. Although there are different turbine designs in development, they all share a common challenge: Oscillating Water Column (OWC) devices convert wave motion into alternating expansion and compression cycles within an enclosed air duct. The air flow inside the duct can be compared to inhaling and exhaling. This reciprocating air movement is used to spin a turbine. The challenge lies in how to spin the turbine continuously in only one direction while the air stream is moving back and forth.

  OWC technologies are the most mature and well-studied of all the other wave energy conversion systems. OWC turbines have been around for over thirty years; no other WEC system has produced as much utility-grade power to the grid. OWC structures offer an efficient means of conversion: they filter irregular wave patterns which yield a tight, resonant bandwidth. Also, baffles that are built inside the capture chamber help to dampen and slow down the frequency of incident waves, thus allowing the contained water to continue oscillating after a wave passes by. This stored energy results in a more even amplitude for efficient wave to wire conversion.  The reason OWC turbine designs have not made it big in the global market is because they are either too inefficient or too complex and costly to manufacture and maintain.  The Hanna Turbine promises to overcome all of these issues.

  Four types of OWC turbine designs include: (1) Impulse turbines which show promising efficiency coefficients and are relatively inexpensive to manufacture. Research from 2009 (V. Jayashankar, M. Takao, T. Setoguchi, et al.) favors a twin impulse turbine topology.  Another biradial impulse turbine has been described by Luis Gato and Antonio Falcao with the Instituto Superior Tecnico, Portugal.  Currently, Oceantec Energy, S.L. and Tecnalia are testing this design called MARMOK A-5, at the Bimep ocean test site near Armintza, Spain; (2) axial turbines like the Denniss-Hunter Turbine used by the Australian company Wave Swell Energy; (3) the pioneering reaction-type Wells Turbine. While the Wells Turbine does spin in one direction, it has numerous weaknesses: its symmetrical blades stall easily, has issues with low-speed operation, has a small operating window, and is difficult to self-start under many conditions, and (4) the Hanna Turbine, a unique dual rotor, mixed flow impulse and reaction type turbine that has both high-lift asymmetrical axial blades and radial vanes for maximum efficiency. The Master's Thesis from France's Paris Tech (see the report posted above) predicted 70% efficiency for the Hanna Turbine based on numerical simulations and monodimensional (mean-line) analysis.  The predicted 70% efficiency figure only takes into consideration the output of the axial blades.  Had the study combined both of the turbine's two primary drive components i.e., the radial vanes and the axial blades, the efficiency numbers would be higher.  A recent mono-radial OWC design by John Hanna shows how radial vanes contribute to angular momentum.  A photo of the mono-radial prototype is at the bottom of the page.

  Wave energy developers such as AWS and the former Wavegen have embraced the Wells.  As a result, a great deal of technology development has gone into attempting to enhance and improve the operation of the Wells, including a large body of work from Japan and India. The Dresser-Rand corporation has teamed up with Siemens to develop an optimized impulse-type turbine. The D-R brochure describes their variable radius turbine (VRT) that will be tested in Hawaii in 2019 on the new Ocean Energy OWC floating platform.  Continued refinements of the Wells will only achieve modest improvements in efficiency and operating window.  Alternatives to the Wells and impulse turbines are needed.  The Hanna Turbine shows the greatest promise for improving the efficiency of OWC turbine technology.


HANNA TURBINE                                        VERSUS                                       WELLS TURBINE

                               1. Dual rotor                                                                                                                 Single or dual rotor

                               2. Low speed operation                                                                                                High speed operation

                               3.Develops more torque at lower speeds                                                                     Requires high speeds at lower torque

                              4. Asymmetrical airfoils for increased lift                                                                   Symmetrical airfoils for poor lift

                              5. Low angle of attack for more lift and less stalling                                                     High angle, poor lift and stalls easily

                              6. Better self-starting                                                                                                      Poor self starting

                             7. Wider operating range                                                                                                Narrow operating range

                              8. Less damping (resistance) to air flows                                                                       Greater resistance to air flows

                              9. More versatile with three configurations                                                                   One configuration

                              10. Two generators placed in dry environment...                                                          One generator in wet environment

                                  OR two annular, ring-type generators built into rotors

                             11. Low noise due to diffuser rings and low speed operation                                       Very noisy, blade tip vortices

                             12. Impulse and Reaction Turbine (Radial vanes and Axial blades in each rotor)        Reaction type turbine

                             13. Wave OR tidal energy conversion                                                                          Wave energy conversion ONLY 

  The Hanna Turbine (HT) is an uncomplicated design.  Its two rotors are the only moving parts. It offers long-term survivability for decades of low maintenance service. The unique dual rotor configuration can drive two generators, effectively doubling electrical output. The HT is essentially two distinct axial/radial turbines that will extract more energy from a bi-directional air flow. This is accomplished without the need for complex and expensive variable pitch or counter-rotating blade mechanisms. The HT can be deployed anywhere in the world as long as a suitable wave climate exists. Environmental studies for similar WEC devices now in place, have all resulted in "Findings Of No Significant Impact". No commercial fisheries will be effected.


  To underscore the remarkable versatility of the Hanna Turbine, the design can also be easily modified to function as a TIDAL turbine.  The tidal design application is covered by the existing Hanna OWC turbine patent.  Because water is denser than air, this iteration does not require the "Radial Collector Vanes", split flow ducts or "Curved Central Guide Vanes".  The dual axial blades are all that is needed to efficiently harvest tidal energy.  The submerged platform is fixed to the bottom in line with the tidal flows.  The rotors respond to the alternating flows so one rotor will be in the "drive" mode whilst the other is in the "freewheel" mode. As tidal flows switch, so does the drive modality of the turbine's axial blades. Regardless if the tide is going in or out, the unit will produce electricity without the need for complex variable pitch blades or yaw adjustments.  Simplicity and versatility is unique to the Hanna Turbine design. The ability to be used as either a wave energy converter or as a tidal energy converter, sets the Hanna Turbine far and above all other OWC and tidal turbine designs!  Click HERE and HERE to view two short videos of the Hanna Tidal Turbine on YouTube.

The two images below show a fractional-sized 'bent duct' version of the Hanna OWC Wave Turbine.  The sketch at the top of the page shows the 'inline' version of the Hanna OWC Wave Turbine.


Above: a prototype for the 'bent duct' version of the Hanna Axial Reaction-type OWC Turbine.        

Above: a prototype for the Hanna Radial Impulse-type OWC Turbine using an improved high volume ambient air inlet.

There are other patented and proprietary Hanna Designs:

1)  A mechanical direct-drive wave energy converter for shore-based, surface and subsurface Power Buoys.  Click HERE for details.

2)  A small deep ocean autonomous buoy for research and data gathering.  Click HERE for details.