Renewable ‘Blue Energy’ to revolutionise the world
Could blue be the new green?
Osmotic power or blue energy is a renewable energy source that converts the difference in the salt concentration between water with high salinity and water with lower or no salinity, into hydraulic pressure. As water molecules move through a semi-permeable membrane from one part to another, the difference in the solute concentration will cause low-salinity water to move quicker to the side with high-salinity water, increasing its pressure. As a result, this hydraulic pressure is used to drive turbines that produce electrical energy.
A team of scientists from Nature have created a way of generating and harnessing more osmotic power by using a single-layer molybdenum disulphide (MoS2) nanopores, a much thinner membrane. This is because water that passes through a membrane scales inversely with membrane thickness. It is estimated that 1 sqm membrane could generate a whopping 1 megawatt (MW) of electricity. This is enough to power up 50,000 energy-saving light bulbs!
Osmotic power is increasing through time. Although this phenomenon can occur naturally where a river meets the sea, man-made water sources provide higher outputs of energy as higher differences in salinity generate more power. The world’s first osmotic power plant using pressure retarded osmosis (PRO) was created by Statkraft, in 2009. Located in Norway, the power plant proved to be inefficient as it was neither cost-effective nor generating enough power, and it was closed in 2013. However, recent findings have made osmotic power a viable process in generating high amounts of renewable energy.
Since earlier osmotic power plant prototypes have generated insufficient energy, this discovery could revolutionise energy as it can produce 2 terawatts (TW), equivalent to 2,000 nuclear reactors. Furthermore, unlike other types of renewable energy sources such as solar energy and wind energy, osmotic energy can be produced regardless of time or situation.
