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The Davidson Hill Venturi Turbine

In October 2003, Tidal Energy Pty Limited (TE) achieved the world record result of the highest efficiency 384% (compared to an open turbine in free stream) ever achieved from a hydraulic turbine, eclipsing the former record of 325% set by Grumman Aero Space engineers in 1978.

Earlier in November 1998 TE founders Hill and Davidson concluded that moving water had the greatest quantum of resource of clean, green, renewable, cost effective, sustainable energy available to an energy starved world.

Tidal Energy Pty Ltd was formed by Davidson and Hill to research, develop and market a technology that would be capable of harvesting the energy in moving water in tides, ocean and river currents in a cheap and practical way.

The Davidson-Hill Venturi Turbine is a turbine that is housed in a venturi shroud or duct. This shroud accelerates flow across the turbine, boosting the turbine efficiency by 3-4 times).

The technology has proven that it is able to be deployed over a wide variety of sites from run-of-rivers to seaways and open oceans.

Depending upon site conditions, it can be slung under a floating pontoon in sheltered waters or fixed to the seabed in the open ocean. In seaways and open oceans where the currents vary in direction, the turbines are fitted with a "passive" swivel based allowing the turbine to always intercept the flow at the optimum angle.

Each size of turbine can be fitted with an off-the-shelf generic gearbox capable of generating a few hundred kilowatts to megawatts depending on the site and the power requirement. Turbines can also be grouped in arrays to provide multi megawatt supply.

Central to the research conducted by TE was the "venturi principle" (see Figure 1). In essence, a venturi is a constriction or narrowing of flow in a channel or pipe. This constriction causes a relative velocity increase and pressure drop as flow speeds up through the constriction.

It was postulated by Tidal Energy that such a device, housing a turbine at the constriction for energy extraction, may be able to speed the flow of water across the turbine allowing the turbine to extract energy more efficiently, but most importantly from water flows that were too slow for commercial energy production or supply.

By late 1999, TE had tested several sizes of venturis (See Figure 2). Testing was carried out in the Queensland Government Hydraulics Laboratory at Deagon near Brisbane. By the end of 2002 Tidal Energy founders had achieved turbine efficiency increases of over 200%. Whilst a good start they believed there was a lost more potential to be extracted.

In 2002 following more research and development Tidal Energy produced a turbine housed in a unique venturi of their own design that produced the staggering result of 384%. This is the marine equivalent of breaking the speed of sound!

This version of the venturi (The Davidson Hill Venturi Turbine) became the focus of Tidal Energy's research resulting in several Patent Co-operation Treaty (PCT) applications being filed to cover the America's, UK (including Europe) India, China, Japan, Indonesia, Brazil and New Zealand.

In 1999, 2001 and again in 2003 the evolving Intellectual Property and technology being developed was filed with the Australian Patents Office.

Tidal Energy has undergone rigorous due diligence by every level of Australian Government prior to being awarded major funding Grants allowing Tidal Energy to be taken to its current level of development.

In 2002 TE built its first full size model new of the patented Davidson Hill Venturi This proved to be an outstanding success proving beyond doubt the effectiveness of the design.

In order to prove scalability and to complete further beta testing Tidal Energy was awarded a grant to build a second and larger Davidson Hill Venturi Turbine, to be tested in and around the South East Queensland region to map the energy resource.

The turbine was over 10 feet high and 16 feet wide (the largest in the world of its kind) and was deployed via a purpose designed project vessel. Using this methodology Tidal Energy tested the scalability of the venturi turbine technology successfully in Aug 2005.

Tidal Energy has developed industry alliances with key research facilities on the Gold Coast working with internationally turbine experts Professor Rodger Tomlinson who heads the Centre for Costal Management at Griffith University Gold Coast Campus and Dr. Brian Kirke former Senior Lecturer also from Griffith University on the Gold Coast, who has a PhD in turbine design and acted as an independent third party collecting publishing results.

Aaron Davidson

Craig Hill

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