Miniature turbine could kick-start cheap desalinisation

Scientists at GE Global Research (GRC) are working with the US Department of Energy to develop a super efficient desalination machine that fits in the palm of the hand by shrinking a steam turbine originally designed to generate electricity.

If successful, the system could reduce the cost of water desalination by as much as 20%. They claim that would begin to break down the cost barrier that has prevented more desalination systems from being built.

The mini desalination system combines 3D printing with GE’s knowledge of turbo-machinery and fluid dynamics. GE scientists Doug Hofer and Vitali Lissianski used them to shrink a power generation steam turbine that would normally barely fit inside a school gym.

Hofer, a senior principal engineer for aero systems at GRC and a steam turbine specialist, was part of a team of GE researchers working on a project for Oil and Gas to improve small scale liquefied natural gas production. A key part of the project focused on using 3D printing to miniaturise the turbo expander modelled after a GE steam turbine.

Hofer explained: “In traditional steam turbines, steam condenses and turns to water. We thought maybe the same principle could be applied to water desalination.”

The only difference would be in using flows through the turbine to freeze the brine, or salt water. Freezing the brine would separate the salt and water by turning salt into a solid and water to ice.

97.5% of the world’s potential clean water drinking supply remains untapped, locked in salty oceans and unsuitable for human consumption. This is in the face of growing global water shortage. According to the United Nations, water scarcity impacts 1.2billion people.

The technology inspired by a miniaturised steam turbine could help change all that. Advances in miniaturisation have proven to have great impact. For example, the application of Moore’s Law in the semiconductor world has shrunk the size of computer chips to enable mobile phones that pack more computing power than a roomful of mainframe supercomputers that were state-of-the-art a few decades ago.

In ultrasound, miniaturisation technologies have shrunk consoles to the size of a phone screen and can fit neatly into a doctor’s coat pocket. Doctors today can deliver high quality care in regions where access was previously limited or non-existent.

Steam turbines spread electricity to homes and businesses. Miniaturised, Hofer and Lissianski say, they may also hold the key to spreading water desalination around the world.