USA: Synthetic Seabed Carpet to Produce Electricity from Waves

A new device, that is not yet built, will mimic the wave-damping effect of a muddy seafloor thus extracting energy from waves passing over it, Environmentalresearchweb.org reports.

A synthetic “seabed carpet” will offer a new way of producing clean and cheap electricity and at the same time will protect the coastal areas against strong waves and provide safe haven for boats during storms.

The carpet’s inventor, Mohammad-Reza Alam of the University of California, Berkeley said: “If mud can seriously take so much energy out of ocean waves, then why don’t we use this idea to design a wave-energy convertor that’s very efficient?”

This flexible carpet will act just like mud; it will dampen the waves that pass overhead extracting the wave perturbations to generate electricity. This system could easily absorb 50% of incident wave energy over short distances of about 10 m.

Alam found out that when wave-damping conditions are strong a considerable amount of energy is converted from “surface mode” waves to “bottom mode” waves, and he added: “If damping is strong, the overall energy absorption from the ocean is even stronger.”

Alam believes that his “carpet of wave-energy conversion” (CWEC) technology has certain advantages compared to other wave-harvesting techniques. Some of those advantages are the resistance of the device to storms, and it even performs better in storms. Also it can use any type of wave approaching from any direction to generate electricity. The device would not pose a threat for ships nor for marine mammals.

The disadvantage of the CWEC is that its efficiency decreases with water depth, meaning that it is only suitable for use between the surf zone and depths of about 20 m.

Dominic Reeve of Swansea University in the UK stated: “It is an interesting idea but there are practical issues such as the cost of installation and maintenance, impact on bottom-dwelling marine life, and the impact of tides on the performance.”

He also added that: “If there is mobile sediment around, this carpet could well affect sediment transport – either to the detriment or advantage of itself or neighboring areas.”

Alam suggested that this problem could be resolved by deploying the device in rockier coastlines.

Subsea World News Staff , June 20, 2012