For its breakthrough, the Siemens Water Technologies team yesterday bagged a $4 million grant from the Environment and Water Industry Development Council (EWI).

Taking the salt out of sea water to make it drinkable is now a famously energy-guzzling - and expensive - process.

Professor Lui Pao Chuen, who chairs the EWI's evaluation panel, noted that over 80 per cent of the current costs of desalination goes into paying for the energy required.

The Siemens team, responding to the EWI's challenge issued last year to design a more energy-efficient desalination technique, beat 34 other teams in coming up with its desalination method.

It used electricity instead of high pressure or heat to remove salt from sea water, and produced a cubic metre of pure drinking water on 1.5 kilowatt-hours (kWh) of power.

Desalination methods around the world now use twice that amount of power.

While conventional desalination methods push water through a membrane, the Siemens team's method involves passing sea water through electric fields to draw out its salt, explained Siemens vice-president of R&D Ruediger Knauf.

PUB technology director Harry Seah described the novel approach as one which 'blows convention away'.

Prof Lui agreed, saying: 'This is what we call disruptive technology - and it's exactly what we're looking for.'

Siemens will work with national water agency PUB over the next three years to put the technology through further tests.

Sea water, though an abundant resource, has yet to be tapped as a viable source of potable water worldwide because of the high costs of desalination.

Most countries have thus turned to rainwater, while a handful have embraced recycled water.

Singapore's reclaimed water, Newater, needs only 0.7 kWh to produce one cubic metre of ultra-pure water.

More energy-efficient desalination will be a boon to coastal cities like Singapore, said Prof Lui.

Desalination is now one of this country's four 'national taps'. The process supplies up to 10 per cent of the national usage, with the other three taps - reservoir water, imported water and Newater - providing the rest.

Mr Seah said that if the new energy-efficient technology passes more rigorous tests, desalination could become more widely used here to make Singapore more self-reliant in water.

News of this new technology is a prelude to the cutting-edge technologies that will be on show at the Singapore International Water Week, which officially opens today.

The four-day event at the Suntec convention centre has attracted over 5,000 delegates and 390 companies in the water-technology business.

taniat@sph.com.sg