The deal with desal – damn the costs!

Desalination plant at Port Stanvac which services Adelaide

Desalination plant at Port Stanvac which services Adelaide

So what’s the deal with desal? Desal is the Australian shortened slang for desalination. A desal plant is a desalination plant, though sometimes Aussies will refer to it as the desal.

Australia has a very unsecure water supply. With little rainfall compared to other nations the rainfall can also be very inconsistent with long periods of drought not uncommon to the country. What Australia does have a lot of is saltwater. The major Australian cities are all on the coast and the entire country is an Island, the biggest Island in the world and the world’s only continent island. So not enough drinking water? But lots of saltwater? Desalination looks like a dream and Australian’s and Australian politicians can’t seem to get enough.

Every Australian state has at least one desalination plant on the back of promises to secure Australia’s drinking water in the face of droughts and the decline of the Murray Darling basin (the biggest river system in Australia). The desalination plants have spawned massive infrastructure projects and changes in Australian water supplies. Often cities are not connected completely to one water supply. Often they are fed by multiple supplies and never one supply for the whole city. Though it is politically poisonous to have only part of the city connected to the water desalination plant. This sparks new pipe work to connect water supplies north to south and east to west. The pipework in itself is a large undertaking with road being dug up and new pipe laid under a new road. Though this new pipework and longer distances requires more pumping capacity. So upgrades and modifications are made to pumping stations throughout the network. This all adds to the impressive cost of the desalination plant itself.

Detractors of desalination don’t just quibble over the initial capital cost of the plant, pipes and pumping infrastructure required. The cost to run the plant and turn salt water into potable drinking water is very high too. Desalination works by either heating the water to steam or pumping water through membranes applying reverse osmosis, either method is immensely energy intensive. This energy costs money.

Desalination has also raised many environmental concerns. The intake of a desalination plant can dispute the local marine environment causing problems throughout the food chain from plankton to fish. Australian desalination plants in Sydney and on the Gold Coast have specially been designed to intake water at a slow enough rate for fish to escape being sucked in.

The outflow of a desalination plant also causes environmental issues. The outflow of the plant is incredibly salty, a brine. This brine increases the salinity of the local ocean, which again disrupts the ecosystem and food chain. As brine sinks in normal sea water it can accumulate and cause havoc on the sea bed. Careful monitoring and gentle release is required along with excellent planning for the location of outlet vents to use ocean topography to effectively disperse brine.

Despite the rising cost of their water bills, infrastructure disruption to roads and environmental concerns Australians are still in love with desal.