Solar powered steam engine transforms salt water to drinking water

A solar powered steam engine capable of transforming salt water into fresh drinking water has been created by students at Aston University.

Saline groundwater occurs across vast areas in India, Australia, United States, Middle East and other regions and desalination is essential to provide freshwater in arid places remote from seawater, lakes and rivers.Current methods of desalination however, can use substantial energy and can discharge significant amounts of concentrated saline water which pollutes surrounding areas.

PhD researchers Opubo Igobo and Clara Qiu have developed ‘DesaLink’, a new prototype which uses sunlight and steam pressure for the desalination of groundwater. The Engineering students have demonstrated that it can provide freshwater from brackish wells, while operating entirely from solar energy while producing only a minimal waste stream of concentrated brine.

Opubo Igobo said: “As a shortage of freshwater tends to coincide with abundance of sunlight we wanted to make use of existing solar energy to drive the desalination process. We believe the ideal groundwater desalination system should operate using a sustainable energy source and be capable of providing a high recovery of freshwater from saline feedwater.”

The DesaLink system is cheap to run and highly effective and works by linking the solar Rankine cycle to reverse osmosis (RO). Unlike conventional desalination systems, which use electric motors to drive the desalination process, DesaLink uses the pressure of steam evaporated in solar collectors. The linkage system between the steam piston and the high-pressure pump, which is designed for maximum efficiency, is the novelty of the design. DesaLink also uses a batch rather than continuous process seen in many other desalination systems.

The prototype unit has been designed entirely at Aston University and built in partnership with DuRose Ltd, a company in the West Midlands. It is planned for the pilot scale system to be tested in the Punjab region of India.