Alternative hyrdo power source

Thursday's edition of The Columbian in Vancouver contained an article about an experimental form of hydro power. University of Michigan researcher Michael Bernitsas has developed a system to take advantage of the vortices naturally created by currents.

A vortex is an eddy or a whirlpool created by water (or air) flowing past an object. In rivers, vortices have traditionally been a challenge for engineers because of the pressure and vibrations they create in underwater structures. Bernitsas has worked for years to control these vibrations, but recently began work to harness them.

He designed a system of cylinders that are placed perpendicular to the river's current. The current causes the cylinders to move up and down which can be used to generate electricity.

Bernitsas hopes that his system will provide a greener alternative to hydroelectric dams. Unlike the turbines in dams, the cylinders do not contain blades and should reduce the level of risk to fish that traditional hydroelectric power has posed. The system is also designed to work with currents as slow as one knot, while dams require a speed closer to 5 knots to work. According to Bernitsas, most rivers in the world are flowing at speeds of 2 to 3 knots.

The system has yet to be field tested, but Bernitsas has several experiments lined up to determine its long-term viability. If it proves successful, Bernitsas' work has been considered as a possible option for use with the Columbia River Crossing Project in the Portland/Vancouver metro area.

Blue energy?

We have all heard of hydroelectric power and its accompanying benefits and challenges. Though it is a zero-waste source of energy, the environmental-and often social, geographical, etc-impacts of damming a river are considered too high by many to consider it a sustainable source of energy. Tidal power, likewise, has potential environmental impacts that keep some from embracing it.

There is a third way to extract energy from water that has not received as much attention. Currently at use in the Netherlands and Norway, osmotic power uses the conflicting powers of salt water and fresh water to produce electricity. The two types of water are brought into contact by passing through anion and cation exchange membranes, which generates chemical potential energy, which is than converted into voltage.



Until recently, the technology has been prohibitively expensive to install but a recent development has made it cheaper. The membranes can now be made with polyethylene plastics, the same material used for most grocery bags.

Like other forms of hydro power, there are zero emission associated with the process, though there is an initial carbon debt due to manufacture and installation of the equipment. The only waste produced by the osmotic process is brackish water, which could have an impact on the area water systems.