HIGH EFFICIENCY NEXT GENERATION TECHNOLOGY
Competitive benchmarks for the Wave Energy Converter (WEC) industry have been well established by the mature wind and solar industries. Wave energy power plants are expected to have a competitive advantage by producing more consistent electricity. This is expected to reduce the total cost of the electricity as back up generation costs will be much lower.
However numerous studies and reports have indicated viability of first generation WEC technologies which have subsequently not been demonstrated. Lack of genuine and transparent performance data is undoubtable a major issue facing the industry with a notable lack of authentic results based on average electricity produced still not publicly available by a number of developers promoting high performance. A number of these devices either use air turbine systems or operate under water where there is less energy.
OUR DEVELOPMENT PATHWAY
Though our technology development we have aimed to distance ourselves from the competition. By insisting on best practice procedures of measuring average electricity production to provide performance results, has not only built confidence in our results and projections for large projects, but has also been substantial in identifying where further performance increases may be attained.
Our development has been based on the premise that a viable WEC technology will firstly need to be a highly efficient across the range of wave heights, and especially across the small – medium range of wave heights for commercial, levels of electricity and, revenues to be realised. The Hybrid Float energy extraction /PTO system at the heart of the Perpetuwave technology was devised by mathematically modeling the energy extraction process.
Motion of light weight and weighted floats in waves – Compliments of Wikipedia
The light weight float at the surface moves much further, and is the only float with positive operating buoyancy, which in effect is excess energy that can be extracted to produce electricity!
The animated image readily shows the 2 heavier floats are shown to have much less movement, and the force over distance formula indicates less energy could be extracted by underwater systems
Key features of the Hybrid Float system include;
- The Hybrid Floats / High performance & low Capital costs – The floats are rectangular in shape with the long side parallel to the wave fronts. This offers the highest possible buoyancy loading possible as the length of the float is immersed in a wave front at once and is then moved up over the wave. This design also offers the lightest weight floats possible with a working buoyancy / float and trailing arm weight ratio of 4:1. The elongated floats also easily extend wider for a larger capture width and multi MW commercial units.
- Low wave degradation high energy density energy extraction process / High efficiency & equipment utilisation, low capital costs – The upwards angular motion of the floats offered by the trailing lever arm is also in the direction of wave travel so energy can be extracted from the substantial horizontal directional component of the wave energy (the direction of wave travel) as well as the typically converted vertical energy component. This reduces wave reflection (allowing more energy through to the following floats) and thereby reduces impact loads of breaking waves and allows a series of floats to be effectively placed one behind another in a viable array formation.
- Robust Design / Lower weight, capital costs and lower O&M costs – The linked float design of the Xtracta is a very simple and robust system.
The net benefit of these set of features is high performance, which lowers capital cost per rated capacity or per kWh produced and increases revenues via higher sales of electricity.
FULLY ‘MARINISED – LOW RISK’ DESIGN
The Wave Xtracta technology also offers a number of other significant features to provide a sensible and practical design. The result is significant commercial benefit so the cost of electricity is competitive with wind and solar designs. These features include.
- Low Build Cost - The unique linked float system provide a sensible risk managed design. The sleek design has low frontal area, and low wave impact area which jointly minimise loadings imparted. This minimises loads placed on the proven slack moored multi point anchoring system which offers substantial redundancy for a low risk design and enhanced extreme weather capability.
- Low O & M costs – The housing provided on the deck also offers a dry environment for all the componentry instead of operating in or being exposed to the toxic salt water and barnacle growth. This dry operating environment ensures land based component longevity and minimal maintenance. The housing also offers 24/7 accessibility for low cost maintenance and repair without the need for expensive Scuba Divers or towing back to port for minor services etc.
- Low environmentally risk - The direct drive train does not use any hydraulic oils for an eco-friendly design.
- Modular in design – Components are shared between different size power plants providing cost efficiency and scalability in production.
DIRECT DRIVE TRAIN
Energy is transferred from the array of light weight hybrid floats and attached trailing arms to a common generator via a simple direct drive system. By harvesting only the upward motion of the floats, a high ratio of positive float buoyancy results and this helps to further reduce reflection of the wave to further improve the genuine viability of an array formation.
The simple direct drive train operates with efficiencies of extracted energy delivered to the generator of approximately 90% . A one way clutch transfers the upward motion of the floats to drive a step up gear box which then drive the common generator for improved drive train and generator utilisation.
The drive train also provides excellent serviceability with any one float being able to be removed from service independent of the rest of the power plant. Off the shelf components are used throughout to complete the cost effective and practical energy solution.