OWEC - Offshore Wave Energy Converters
IPS OWEC Buoy is based on almost twenty years of theoretical studies, laboratory
test, model tests in lakes and full scale trials in the open sea.
The system is very flexible and will produce electrical power with high efficiency - a
total yield of 30 - 35% from waves to electricity is normal under good conditions.
The basic unit in the IPS-OWEC system is a circular or oval buoy with diameter and
weight adopted to the predominant wave situation at the place of location.
The buoy is held in position by an elastic mooring enabling it to move freely up and
down against a damping water mass contained in the long vertical tube - the acceleration
tube - underneath the buoy. The relative movement between the buoy itself and the water
mass is transferred by a working piston in the acceleration tube into an energy conversion
system located within the buoy hull.
Production buoys with diameters from 3 - 4 m up to 10 - 12 m can be arranged in groups
from 5 units and upwards. Every unit can be a complete power station. Alternatively groups
of IPS OWEC Buoy may be connected to a central generation unit.
For best performance a water depth of minimum
30 m is required. The design can be
modified to operate also in shallower waters but with reduced efficiency.
The IPS system also has built-in overload protection arrangements, control programs and
instruments to adept the function of every buoy unit to changes in the wave height, wave
The simulation programs developed by IPS give a very accurate picture of the
OWECs behavior in various situations. For proper estimation and design it is
important, however, to have detailed long-term wave data from the proposed location.
The internal energy conversion system within the IPS OWEC Buoy can be of different
types. Traditionally an oil hydraulic system has been used. This has been built up of well
known standard components - cylinders, accumulators, valve blocks, hydraulic motors etc.
which guarantee good serviceability and long life.
A new interesting alternative for the internal energy conversion is based on a set of
hose pumps driven by the piston in the acceleration tube, pumping water to a small turbine
directly coupled to a special generator.
The IPS system design alternatives are protected by a series of international patens.
The latest patents where filed in 1996 and have been granted in a number of countries -
applications in other countries are still pending
In the waters west of Scotland and Ireland where the power "content" in the
waves is in the order of 50 - 70 kW/m wave front, a 10 m IPS OWEC Buoy will reach a power
of 150 - 250 kW and produce more than 1.4 GWh of electric energy per year.