A previous version of this page described the first Hanna Turbine, US patent 8,358,026. The original Hanna Turbine is both a wave and tidal energy converter. The full patent for the first Hanna Turbine has been acquired by HydroWing Ltd, an established tidal energy developer in the United Kingdom. The new owner and its multi-national partners enjoy a substantial economic and technical advantage over competing technologies. This is because the Hanna design has no gear box and uses fixed-pitch blades to harness cross-current tidal flows. Expensive variable pitch mechanisms are unnecessary. Its large diameter, multiple blade rotors efficiently extracts power from bi-directional tides. The simple Hanna drive line is key to the turbine's versatility. In January 2021, a new Hanna Tidal Turbine was issued a provisional patent and is described at the bottom of this page.
The information below describes the unique Hanna wave energy turbine:
THE HANNA MONO-RADIAL TURBINE IN OWC CONFIGURATION
In-house Proof of Concept testing has been successfully completed for the mono-radial turbine by Oregon inventor John Clark Hanna. In February 2021, the U.S. Department of Energy's TEAMER program, awarded a grant of funds to have CFD and numerical modeling done by Alden Research Laboratory, Holden, MA. The study will optimize the mono-radial closed loop design and Alden's final report will be available to the public in February, 2022. The new radial power take-off (PTO) is a novel and exquisitely simple wave energy converter. From the exterior, the method of air intake appears to be self-evident. But inside the turbine's casement, there is a proprietary method of directing the air. The full force of the incoming air flows are efficiently harnessed to increase the rotational driving force.
Unlike common OWC (Oscillating Water Column) impulse turbines, the new Hanna PTO somewhat resembles a Pelton Wheel. It is a radial, self-rectifying air wheel that does not use valves, sensors or solenoids to help the rotor turn in one direction. Peripheral collector vanes help develop optimal momentum. The Hanna design uses a special air-cored, axial flux generator which avoids the magnetic resistance and drag that normally hinders a turbine's forward motion and torque.
The Hanna Mono-Radial Drive is versatile. It can also operate within a sealed closed loop system. The closed loop system has a balanced air flow in both directions. Unlike the OWC application, the closed-loop version is never exposed to corrosive salt water mist and the resulting marine slime that coats internal parts. The closed loop system can be miniaturized and is ideal for charging batteries on board small autonomous, extended mission research and data gathering buoys. To read the Closed Loop Turbine patent, click HERE.
THE HANNA MONO-RADIAL TURBINE IN CLOSED LOOP CONFIGURATION
When operated as a full-size OWC-type converter, the design will generate utility-grade power from shore-based installations, surface buoys or fully submerged buoys that are out of sight from the shore. The subsurface buoy's excitation force is caused by the fluctuating pressure differentials created by passing waves above the structure and the relatively static pressure at the buoy's lowest point. The subsurface buoy can be driven by either the Hanna mechanical direct-drive PTO, the Hanna Mono-Radial Turbine PTO or the Hanna Coaxial Impeller drive. Two DOE-funded evaluations for the Hanna Subsurface Power Buoy and the Hanna Mono-radial drive are currently underway. To learn more about the proprietary subsurface buoy, click HERE.
THE HANNA BI-DIRECTIONAL TIDAL DRIVE
The Hanna Cross-Current Tidal Turbine was inspired by the single flow Bánki-Michell turbine that has been used in hydropower plants for over a century. The new bi-directional design is a PTO that only turns in one direction regardless of which way the incoming or outgoing tides flow within estuaries or where rivers empty into the ocean. Unlike wind and solar technologies, tidal energy can be predicted years in advance and is 100% reliable.
The new PTO has a low profile. It functions in the horizontal or vertical position. Its foundation and nacelle are constructed of pre-cast structural concrete sections. Multiple units will sit on the bottom of a river or can be incorporated into a tidal barrage like La Rance in France or the proposed tidal lagoon in Swansea Bay, Wales. The turbine is well suited for tidal lagoons with a low head but high flows.
Lighter tidal drives, with their nacelles made of sheet steel, can be fixed to a submerged framework, mounted beneath an anchored floating platform or suspended from a swinging pontoon bridge. Simplicity of the design keeps the LCOE exceptionally low; there are only two bearings to maintain. The generator or rotor assembly can be easily raised for servicing using common, non-specialized work vessels. To read the full patent application, click HERE.
More Hanna Innovations:
For information on the Hanna Subsurface Buoy click HERE.
For information comparing competing designs for the Hanna Subsurface Buoy click HERE.
For information on the mechanical direct-drive PTO click HERE.