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Desalination

There are two main kinds of desalination: reverse osmosis and multi-effects.

Reverse osmosis separates salt from water by pushing salt water through a membrane to separate salt from water. Multi-effects evaporates salt water using a vacuum and recondenses the vapor into drinking water. Both require energy, usually between 2.7-4.5 kilowatthours per kilolitre, but new technologies and methods constantly push that figure lower. Ultimately, the laws of physics are not expected to present insuperable barriers to further reductions before about .7 kilowatthours per kilolitre. At present, pumping Murray River water to the Upper Spencer Gulf consumes up to five kilowatthours per kilolitre.

While both reverse osmosis and multi-effects use electricity, multi-effects can also use heat as an energy input, skipping the initial conversion into electricity and increasing efficiency. By having reverse osmosis and multi-effects desalination operate side-by-side powered by solar energy, thermal storage and a backup gas turbine backup, operational efficiencies can be reaped that lower costs.

At Port Augusta, Acquasol will be desalinating water using multi-effects. However, the plant is configured so that reverse osmosis could be added in the future to create additional operational synergies.
Reverse Osmosis
Multi-Effects

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"On any measure, this is an extreme drought. Climate change has hit in a much more dramatic manner that what we ever anticipated. As we go around Australia, each of the cities has faced an incredible reduction in the inflows to their storages."
Ross Young,
Water Services of Australia 		 "Though expensive, large-scale desalination plants have become necessary, essential infrastructure for Australian cities as we confront the challenge of climate change,
Penny Wong,
Australian Federal Minister for Climate and Water

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