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This study investigates the applicability of Adaptive Neuro-Fuzzy Inference System (ANFIS) technique to predict the performance of a non-buoyant body typed wave energy converter. The non-buoyant body typed wave energy converter is a novel device which uses a water filled container as front end interface instead of a traditional buoyant buoy. A lab scale experimental investigation on the energy conversion efficiency of the device and its heave response were carried out on a small scale model and found that the results were competitive when compared with a buoy typed wave energy converter. Soon after the experimental validations, mathematical model of the device was developed and tested for predicting the device behavior during various wave conditions. To test the viability of a soft computing tool to predict the behavior of a non-buoyant body typed wave energy converter, Adaptive Network-based Fuzzy Interface System was selected due to its predictive ability in uncertain environment. Further, four ANFIS models were developed, trained and validated with the recorded data and applied to predicting the heave response in various wave conditions. The validation results confirm the applicability of the developed ANFIS models for predicting the device behavior over a wide range of wave parameters. The study demonstrates that the ANFIS model is capable of predicting the device behavior with a high degree of accuracy at minimum time. Once modeled, the ANFIS model can be used on behalf of the experimental setup to carryout further experiments to perform the optimization process.

Harvesting the energy from ocean waves is one of the greatest attractions for energy engineers and scientists. Till date, plenty of methods have been adopted to harvest the energy from the ocean waves. However, due to technological and economical complexity, it is intricate to involve the majority of these energy harvesters in the real ocean environment. Effective utilization and sustainability of any wave energy harvester depend upon its adaptability in the irregular seasonal waves, situation capability in maximum energy extraction and finally fulfilling the economic barriers. In this paper, the front end energy conversions are reviewed in detail which is positioned in the first stage of the wave energy converter among other stages such as power take off (PTO) and electrical energy conversion. If the recent development of these front end energy conversion is well known then developing wave energy converter with economic and commercial viability is possible. The aim of this review is to provide information on front end energy conversion of a point absorber and emphasize the strategies and calamity to be considered in designing such kinds of devices to improve the energy harvesting competence. This will be useful to the engineers for speeding up the development of a matured point absorbing type wave energy converter.

This paper describes an innovative method of using a non-buoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a non-buoyant body for conventional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with non-buoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improvement in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters. � 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.

To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies (buoys) which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non-floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network (ANN), the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%. � 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.

A novel method of improving hydrodynamic efficiency by using a cylindrical non-buoyant body instead of floating body in point absorber type wave energy conversion is studied. The proposed novel method has the potential to significantly improve the energy conversion rate and reliability when compared to other recently proposed devices. To illustrate the improved performance and reliability of the proposed device, a simple two degree of freedom system was constructed and experimented at a wave tank. Heave response of the non-buoyant body was measured by placing an accelerometer for various wave and device parameters. The instantaneous excited force on non-buoyant body was obtained by calculating net angular momentum from measured instantaneous heave acceleration and system mass. The resulting force conversion shows that the force excited on the body is significantly higher than the force excited by the wave. It was proved from the experiment that this improved force conversion is the result of novel working principle of the device. It is also objective to show that the device use no complicated mechanisms like latching control, damping control, change of float forms or moving parts like flaps to improve the heave response.