Converting Salt into Energy
Renewable energy can be harnessed where rivers meet the sea.
Nature’s constant pursuit for balance has resulted in scientists developing a new source of energy. One way in which nature pursues balance is through osmosis. When a concentrated solution and a diluted solution are separated by a permeable membrane, osmosis is the spontaneous movement of the concentrated solution in the direction of the diluted solution. This spontaneous movement is what scientist have been able to harness to create energy.
Pressure retarded osmosis (PRO) is a power generation method that takes in river water and seawater on either side of a semi-permeable membrane. The flow that is created as the less-salty water crosses the membrane towards the pre-presurized salter side is sent through a turbine to generate power. The MIT team evaluating the effectiveness of PRO systems have made two important conclusions.
- There is no linear relationship between membrane size and energy production. The amount of energy generated as the membrane size increases levels off. While a system may be able to produce the maximum amount of power at a certain membrane size, it could also produce 95% of the power with a membrane half as large. Finding the optimal membrane size necessary to generate power will help lower the upfront costs of installing a PRO system.
- More power is generated as the saltiness ratio increases. The team found that more energy was generated when they used brine, a byproduct of desalination, and treated wastewater versus using river water and sea water. It was determined that a PRO system could power a coastal wastewater-treatement plant by taking in seawater and combing it with treated wastewater.
Creative Challenge
An active area of research is determining how to pack a lot of membrane into a small volume. I am sure the team would appreciate any suggestions on how to effectively fold the membranes.
If you liked this post, I would really appreciate it if you’d hit the Recommend button below, which will mean more people will see it. Similar writings can be found in my Medium Collection Creative Individuals and Businesses. You can also find me over on Twitter. Thanks!
