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 moving air 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 in France, compared the Hanna Turbine with the Wells and Impulse Turbines using two advanced predictive methodologies: numerical modelling and CFD (Computational Fluid Dynamics).  In this study, the Hanna design showed better efficiency metrics than the Wells and Impulse Turbines.  Read the Technical Report's ABSTRACT by Théo Delecour below.  This is the Abstract only.  For permission to read the entire Master's Dissertation, 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 Dissertation 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!

  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 or manufacturer.


  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 is testing this design called MARMOK A-5, at the Bimep ocean test site near Armintza, Spain; (2) Variable pitch axial turbines like the Denniss-Auld Turbine which rely on complex movable blades to adapt to the reversing flow every cycle; (3) the pioneering Wells Turbine. While the Wells Turbine does spin in one direction, it is inefficient and has numerous weaknesses: it stalls 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 axial and radial vanes for maximum efficiency.

  Despite the shortcomings of the Wells Turbine, wave energy developers such as AWS, Ocean Energy and the former Wavegen have been staying with the Wells to avoid cost and complexity issues associated with the variable pitch turbines as used by Australia's Oceanlinx. 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 a Wells Turbine connected to a large, unwieldy bowl-shaped inlet to take advantage of Bernoulli's principle.  While it is conceivable that continued investment into Wells refinement might garner a modest improvement in efficiency and operating window, alternatives to the Wells Turbine are needed to advance OWC technologies into the global market.


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 (Axial and Radial blades in each rotor)                  Impulse type turbine

                             13. Wave OR tidal energy conversion                                                                          Wave energy conversion ONLY 

  Proof of concept evaluations have been successfully completed. The Hanna Turbine (HT) is an uncomplicated design with only two 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 turbines that will extract more energy from a given flow direction of the OWC. 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.

  The Hanna Turbine was conceived to develop a self-rectifying turbine that overcomes the shortfalls found in the 30 year old Wells Turbine design. It will be a less expensive alternative to shore-based OWC systems builtat Islay, Scotland, Mutriku, Spain and Azores, Portugal. The former Scottish company called Wavegen, developed a variant of their Wells-based design. In an attempt to improve efficiency, Wavegen hoped to market a dual rotor, counter-rotating Wells Turbine. Unfortunately, the design's complexity introduced added frictional losses due to the multiple gear sets. This reduced any modest gains in efficiency. It was also be more expensive to manufacture and maintain. Clearly, the evolution of the Wells design has hit a wall.

  The patented Hanna Turbine promises to  exceed the power production and performance metrics of all other turbines. Three utility-grade turbine models will be offered as complete, grid-ready packages. The civil engineering, permitting and construction will be done by the utility, government agency or developer that has acquired a Hanna Turbine system. Construction plans will use a pre-determined anchor bolt pattern so the Hanna Turbine can simply bolt into place. The client/owner will be purchasing a turnkey, commercial off-the-shelf (COTS) package that includes everything needed to make clean, renewable energy for decades. As envisioned, the WETGEN business model aims to become a leader in the manufactured turbine supply chain rather than as a wave energy developer.

  To underscore the remarkable versatility of the Hanna Turbine, the design can also be easily modified to function as a TIDAL turbine.  The submerged rotors react to the tidal flow so one rotor will be in the "drive" mode whilst the other is in the "freewheel" mode. As the tidal flow reverses, so does the modality of the turbine's rotor set. Regardless if the tide is going in or out, the two generators will produce electricity at all times. This adaptability and versatility is truly a paradigm shift for marine energy. The ability to be used as a wave energy converter or as a tidal energy converter, sets the Hanna design far and above all other marine hydro kinetic technologies!

  The images below show a fractional-sized bent duct version of the Hanna Turbine.  The sketch at the top of the page shows the "inline" version of the turbine.


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.