Tapping Into Wave Energy

With the approach of winter, swells return to our beaches and pound the shorelines.  The changing seasons bring powerful Pacific storms, sending waves barreling into the coastline in a timeless display of natural power.  The smoothed out pebbles and sand on the beach showcase the waves powerful energy.  Yet, apart from providing a fleeting ride for an occasional surfer, the power of waves has gone largely unused.  How could we have missed this potential energy supplier for all these years?   How much energy could one wave generate?  

The power of waves has gone unused, but this is rapidly changing.  One day ocean swells will be used as a harnessed energy that will power all of our lights at home.  The quest to use ocean waves as a source of energy is not new though.  It stretches back well over a 100 years in California.  However, with many failed inventions and little success, after years of effort by many people and companies, interest waned with the rise of coal and oil powered machines.  

Now, a resurgent interest in wave energy has been ushered in rapidly as environmental awareness is heightened.  With 70% of the world's surface covered by ocean, a remarkable opportunity exists.  According to studies, capturing a mere 0.2% of ocean energy could power the entire world. Just the wave energy off American coasts can provide as much electricity as the nation's hydroelectric plants.  Waves transmit more energy than wind because water is denser than air.  The power density is perhaps 100 times greater.  This translates into the need for less ocean space to produce the same amount of electricity a larger land based wind park generates. This would leave the vast majority of coastal waters untouched.  Think of the opportunities this would open up in respect to environmental savings and opening up other used resources.

There are a few test products out there now that are being used to determine if it is possible to gather wave energy.  One such test is a buoy that is a point absorber design.  The buoy contains a vertical metal spar coiled in copper.  Surrounding this spar a float with magnets rises and falls with each passing swell.  It's almost the same principal as shake flashlights.  The magnet moves past a copper coil generating electricity.  The electricity then is carried to shore through transmission lines along the seafloor.  Development of these buoys for full scale utility use is underway and may be supplying electricity in as little as two years.  

Another device is the AquabuOY 2.0 from Finavera Renewables.  This device is entirely powered by waves.  The hydraulic fluid located inside the buoy is just pressurized seawater, so there are no hydraulic oils on board.  The main elements are a buoy, acceleration tube, piston and hose pump.  Seawater enters the buoy with the rise and fall of each passing swell powering a two-stroke hose pump that pressurizes the water.  The water is then forced through a turbine that powers a generator to produce electricity.  

The ocean remains the greatest potential for untapped renewable energy on Earth.  The push to capture this source of clean power is being chased by corporations, universities, state and federal government and community based organizations.  Companies like Finavera Renewables are riding the wave of public support for clean energy.  They signed the nation's first power purchase agreement for wave generated electricity with PG&E.  The Humboldt County Offshore Wave Energy Power Plant is slated to also provide electricity by 2012 from buoys moored 2.5 miles offshore.  

Unfortunately, there is still the need for adequate environmental review and analysis of potential impacts to marine ecosystems.  Waves may provide a clean source of electricity but environmental concerns still linger...electromagnetic fields existing around the buoys may interfere with marine mammal and fish sensory systems.  Possible physical effects from buoy placement and underwater transmission lines may also alter local wave patterns, currents and beaches.  Other problems still remain unknown until further studies show them.  While the wave energy industry is just now emerging, there is still a long ways to go with it.  It is very possible that it will have long-term success in providing an alternative energy source.  It will take more studies and cooperation, but the light at the end of the tunnel is shining - here is a possible opportunity to help clear other pollution ridden sources of electricity.  

**Reference:  DEEP Magazine, D.E. Putnam, 2008.**