The Design, Development and Manufacture of a Fuel Cell Powered Unmanned Aerial Vehicle for Surveillance Applications

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Energy harvesting eel

Richard Kelso and Maziar Arjomandi

Shannon Leigh L. Mason, Rebecca Helen H. Mills, Zac Daniel D. Nicholson and Christopher Schwarz

(Commenced: 01-Jan-2008,Concluded: 30-Dec-2008 )

Richard Kelso

Maziar Arjomandi

Shannon Leigh L. Mason

Rebecca Helen H. Mills

Zac Daniel D. Nicholson

Christopher Schwarz

While research into the use of ocean waves as a source of renewable energy has been the focus of academic attention since the 1970’s, only in the past decade has commercial interest been directed to the development of cost-effective wave energy conversion installations capable of contributing to energy security and the reduction of carbon emissions; only a small fraction of this interest has been focused in Australia, where dense coastal populations and abundant ocean resources suggest significant potential for the development of wave energy generation.

The present study has two aims: to establish proof of concept for, and measure the performance of, the "articulated attenuator" configuration of wave energy converters; and to evaluate the potential for an offshore wave energy farm in the South Australian ocean.

The first aspect of the project is informed by a detailed literature review of ocean wave physics and wave energy conversion, and has a practical focus on the design and manufacture of the Elver Wave Energy Converter (Elver WEC), a small-scale prototype for testing in a wave tank facility. Elver WEC’s hydrodynamic and hydraulic efficiencies are measured over a range of sea states and compared with the theoretical and experimental efficiencies of a range of other devices; Elver WEC’s hydrodynamic performance is found to be consistent with predictions, while a study of attenuation effects yielded related to its complex dynamics suggest possibilities for increasing the efficient range of wave energy conversion.

Ocean wave statistics yield the distribution of available wave energy over a range of sea states in the South Australian ocean; this is combined with the efficiency matrix of the full-scale Elver WEC over the same sea states, to derive the captured energy at each sea state. The optimal size of the device that operates at its peak efficiency for the greatest amount of time annually can be deduced. Employing a modular arrangement of optimally sized devices in series gives a power output which, coupled with estimated capital and operation & maintenance costs, yields a prediction of generation costs (in c=kWh). The generation costs are estimated to be considerably higher than existing wave converting technologies: a result of Elver WEC’s rigid tuning and corresponding narrow band of high-efficiency wave frequencies. Further improvements to increase this band of efficient wave periods have been suggested.

Experimental verification of the Elver WEC established proof of concept of the articulated attenuator configuration; while a detailed resource study confirmed the potential of the South Australian ocean for wave energy development. The results of both aspects of the analysis suggest that future work in the wave energy conversion of an articulated attenuator device would be best directed toward broadening the range of wavelengths over which the device is capable of high conversion efficiency. A number of possible solutions are discussed: these include staggering the lengths of adjacent segments, such that each articulation is ’tuned’ to a different sea state; and introducing active control to the hydraulic circuit, such that the stiffness and damping of the articulators can tune the device to match incident sea states.

Project Sponsors

· One Steel Whyalla

· Cowell Electric

Project Deliverables

Presentation

Final Report

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Article in the Advertiser

Article in the Whyalla local newspaper