Desalination and water security

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Water security and sustainable use are crucial elements for future development. Agricultural use represents seventy per cent of water use in Victoria and Australia, with the remainder consumed by industry and urban usage. The drought and broader environmental concerns necessitate that Victoria develop alternative water sources to traditional surface reserves and rain-fall.

Desalination is an alternative water source to ensure water supplies for Melbourne, and reduce pressure on traditional water sources.

Desalination technologies

Reverse osmosis (RO) is the preferred method in Australia (64% of national capacity) and worldwide, and is being utilised in the NSW desalination plant. This technology can be used for both salt-water desalination and waste-water reclamation (irrigation water or treated effluent).

Environmental considerations

Environmental impacts are of great concern to the public. Of particular concern are any affect desalination may have on:

  1. Marine water quality and biota – disposal of concentrated salty effluent, and traces of chemicals used in reverse osmosis process;
  2. Vegetation – potential effects of construction and operation of desalination plant on near by vegetation;
  3. Atmospheric emissions (especially greenhouse emissions and nitrogen oxides) – most greenhouse gas emissions come from construction and ongoing use, while other potentially toxic emissions originate from the RO process; and
  4. Noise – protecting amenity of nearby residents caused by high pressure pumps.

RO plants have lower energy consumptions than other desalination technology, which means less atmospheric emissions. It also converts a greater percentage of intake brine into water, which results in greater amounts of drinking water for the same volume of chemicals needed for other desalination technologies.

The reliance on fossil fuels makes renewable energy an attractive investment. Solar powered RO plants exist in rural areas in Australia.

Economic considerations

Membrane technology, especially RO is widely considered to have lower costs than other technologies, particularly in construction and production of drinkable water.

RO is economical for both large and small scale desalination. Flow rates can be increased or decreased, and plants can be expanded by adding extra modules.

Energy costs represent approximately 33% of total life-cycle costs. Commonly cited energy sources considered globally are RO plant with electric power from the local network and RO plant with solar energy. Renewable energy powered plants reduces carbon emissions caused by power generation, but increase water costs.

Conclusions

Reverse osmosis is the preferred desalination option given the drought conditions and the uncertainty of traditional water sources.

RO is the most widely used, can be utilised for salt and waste water desalination, and its environmental impact is relatively low. RO plants can also be expanded to meet future demand.

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2 Responses to “Desalination and water security”

  1. Hi. I am wondering why you have posted this article on your site and invite us to share it. There is no critical analysis of the article. What do you think of reverse osmosis as a technology? More to the point, what do you think of a public policy position where in Victoria we have the imposition of one high energy using / high emissions producing tactic in total absence of a water sustainability strategy, in particular no water recycling plan – or visible intention to develop one.

    The majority of concerned Victorians are increasingly concerned about the Government’s crude approach to water and environmental issues. Need to get rid of Twinkle Twinkle for a start and see if it makes any difference!

  2. Hi Jan,

    This was originally a briefing document I wrote for my Masters of Public Policy, doing the Environmental Policy subject.

    The briefing itself is supposed to be factual, rather than expressing a preference.

    My personal view is that Victoria and Australia need desalination technology. We are facing unprecedented water shortages and drought. The only downside of desalination is its high energy use. On that, I forsee desalination increasing demand for renewable energy, which will stimulate further investment in renewables.

    On this issue, I think the Victorian Government is on the money.

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