Wave Power Introduction
Wave Power is one of our largest renewable energy sources, but until very
recently we have lacked the technologies to harness such raw energy. There
are now thousands of patents describing potential wave energy devices,
but very few have been translated into working prototypes, and even less
in to devices with the survivability needed. However, as the feed in tariffs
for energy derived from marine sources are increased by certain governments,
many new designs are sure to leave the drawing board or CAD file - only
time will tell which ones will form the backbone of the future industry.
Wave Energy Devices
Today’s technologies can be separated into various categories and
often share ideas that have been tried before in other designs. Since
the Japanese experiments with floating Wave Energy converters in the 1970s,
OWC wave energy converters
have been installed on exposed cliffs and coastlines in both Norway and
Scotland. Alternative designs that sit on the seabed are also under trial.
Oscillating Water Columns (OWC)
Oscillating Water Column concepts capture wave energy by harnessing the
movement of air that is caused to oscillate by water surging up and down
below. The shore-based installations such as Wavegen’s grid tied
“Limpet” and a number of similar experimental concrete converters
built on exposed coasts of India, Japan and the Azores, have evolved the
technology, paving the way for the commercial models being developed now.
There is also a healthy level of work being undertaken using OWC technology
either on anchored buoys or various devices designed to sit on the seabed.
Tapchan & low-head hydro turbines
The use of natural and/or artificial tapered channels to provide increased
wave height has proven fruitful for increasing outputs for shore based
OWCs. They also offer
potential to raise and temporarily capture waves which can then drain
back down through low head hydro turbines. A number of devices which use
some form of Tapchan are being developed.
Levers & Hydraulic Generators
These are an entire lineage of wave power converters based on leverage.
The strengths and weaknesses of each design that has been tested (and
often destroyed) have informed the next generation. OPD's floating converter,
Pelamis owes some of its engineering DNA to that laid down by Professor
Stephen Salter in various devices including his famous “Duck”.