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.