MIT researchers work on producing power using saltwater

Mechanical engineers at Massachusetts Institute of Technology (MIT) are researching a model to generate electricity using a mix of river and seawater.

The researchers are working on a method of power generation called pressure retarded osmosis (PRO), wherein two water streams of varying salinity levels are combined to produce energy.

The PRO system could be used to power a wastewater treatment plant by mixing seawater with treated wastewater to produce renewable energy.

MIT department of mechanical engineering graduate student Leonardo Banchik said: "Here in Boston Harbor, at the Deer Island Wastewater Treatment Plant … PRO could theoretically supply all of the power required for treatment."

However, the size of the membrane intended for providing power to Boston’s Deer Island treatment plant needs to be as large as 2.5 million square meters.

Along with fellow researchers MIT professor John Lienhard and Saudi Arabia’s King Fahd University of Petroleum and Minerals professor Mostafa Sharqawy, Banchik based the research on a simplified PRO model.

In the PRO system, river water and seawater is placed on either side of a semi-permeable membrane.

Water from the less-salty stream is passed through the membrane to a pre-pressurised saltier side. The created flow goes through a turbine, thereby generating power.

The researchers say that the quantity of power generated depends on the size of the membranes but would level out after a certain limit.

The National Science Foundation and King Fahd University of Petroleum and Minerals’ Center for Clean Water and Clean Energy has funded the research, which aims to find alternative ways to produce renewable energy.