EXCERPT:
This article is a synopsis of the past and current technology development schemes created to propose the potential of generating power by the physical phenomenon of osmosis. In addition, it offers a new concept in exploring the potential of the Qattara Depression of Egypt and the like, not only for generating power, but also for creating vibrant living communities from these desolate lands.
Osmosis is nature’s gift to life. It is the vehicle that
transports fluids in all living cells and without it, all
biological functions and all forms of life cease to exist!
Osmosis is the spontaneous movement of water, through a
semi
-
permeable membrane tha
t is permeable to water but
impermeable to solute. Water moves from a solution in
which solute is less concentrated to a solution in which solute
is more concentrated.
The driving force of the flow movement is the
difference in the chemical potential on th
e two sides of the
semi
-
permeable membrane, with the solvent moving from a
region of higher potential (generally of a lower solute
concentration) to the region of lower potential (generally of a
higher solute concentration).
The term “Chemical Potential” at times can be
ambiguous and elusive. In fact, it is one of the most
important partial molal quantities. It is the energy source
associated with the activity of the ions of an ionizable
substance. It is equal to the rate of change in free energy of a
syste
m containing a number of moles of such substance.
Chemical potential can be viewed as another form of
energy like electrical, gravitational, momentum, magnetic,
surface tension, etc.
Thermodynamically, this energy is
expressed in terms of what is conventi
onally known as Gibbs
free energy.
To prevent water permeation across the semipermeable
membrane, a pressure has to be imposed against the
permeated flow to equalize the force created by the chemical
potential difference across that membrane. This force is
named osmotic pressure. If the imposed pressure exceeds this
limit,
then
water begins to flow from the region of higher
solute concentration to the region of lower solute
concentration. In this case, the force is named reverse
osmosis pressure.