Q. What was the impetus for the development of the wave-powered desalination system?
A. When Dr. Peter McCabe and Dr. Michael McCormick met in Cambridge, England in 1981, Dr. McCabe's goal was to produce electricity using his articulated-barge system. Dr. McCormick's, recognition that potable water supplies throughout the world were rapidly diminishing, recommended that the system be used to produce potable water, since this could be accomplished directly. Work in the 1970's by Dr. Douglas Hicks and Michael Pleas, using floating buoys to power a reverse-osmosis (RO) system, showed that potable-water production was a plausible goal for wave energy conversion.
Q. What advantage does the OES wave-powered desalination system have over others?
A. There are a number of advantages. The primary advantage is that the barge is designed to produce the product (potable) water directly. The relative motions of the barges excite specially designed salt water pumps that draw in salt water, filter and pre-condition the water, pressurize and pump the high-pressure salt water through a reverse-osmosis (RO) system. Other suggested wave-powered desalination systems are designed to use wave-power to drive electrical generators which, in turn, power pumps to provide the high-pressure salt water to the RO systems. This is a rather inefficient process method and, because of the increased complexity, is prone to system failures.
Q. What improvements have been made, and what is the projected system life of the OES system?
A. A 40 meter long, full scale model of the articulated-barge system was deployed in the Shannon River estuary for about nine years. The reason for the deployment was to determine the strengths and weaknesses of the system, without producing potable water. The model showed that the floating wave pump performed well in pumping oil in a closed hydraulic power take-off system. The hydraulic system was designed to eventually power a secondary salt water desalination pumping system. The present power take-off system avoids the environmental problems associated with the Shannon River model's oil-hydraulic system by direct energy conversion using salt water pumps. That is, the working-fluid and the product-fluid are the same. Based on the Shannon River nine year study and the subsequent improvements in the design by OES, the OES articulated-barge system will have a minimum service life of twenty years.
Q. What is the designed performance?
A. The OES system has been designed and model-tested in the contiguous United States, in the state of Maryland. The design sea state is that offshore of the Delaware-Maryland Atlantic coastline. For the average wave height and wave period near this coast, the OES system is designed to produce in excess of 150,000 gallons of potable water per day.
Q. Are there other goals for the system, in addition to potable-water production?
A. Yes. The OES articulated-barge system is essentially a high-capacity wave-powered pump. As such, other applications of the OES system include the up-welling of deep, nutient-rich waters and sea water irrigation of salt water crops. Included in the latter are medicinal and aromatic plants. These can be grown in arid environments in the coastal regoins, such as along the coastline of Namibia.