Desalination

ENTRY DATE: 04.05.2015 | LAST UPDATE: 04.05.2015

CATEGORIES:

  • Water Resources
  • Securement of quality of drinking water
  • Water intake, Purification

TECHNOLOGIES MATURITY:

Applicable Immediately with Improvements through Ongoing Research

Technology Owners:

  • Government
  • Private implementing agencies

Needs Address

Supply of fresh water for domestic use

Adaptation effects

  • Diversity of water supply to provide a source of water when alternative sources become unusable
  • Resilience to water quality degradation
  • Provides a source of pure water for drinking and other domestic and large scale use
  • Increases water security
  • Increase economic development and therefore heightens economic resilience

Overview and Features

The process of removing sodium chloride and other contaminants from seawater, river water, waste water and contaminated freshwater through either thermal or membrane processes. This is usually conducted at huge plants to provide large quantities of usable water for drinking household, commercial and industrial use. The process results in both pure water and waste water, the latter of which can be used for alternative purposes.

Figure 1: Desalination through thermal processes: water distillation (Source: Filters Fast LLC, 2005)


Figure 2: Desalination through membrane processes: reverse osmosis (Source: HCTI, 2008)

Cost

  • Very high costs for plant construction, running and maintenance
  • Costs are site specific and dependent on the source of water for desalination
  • For reverse osmosis, the costs to desalinate brackish water range from approximately 0.26-0.54 USD/m3 for large plants producing 5000-60,000 m3/day and approximately 0.78-1.33 USD/m3 for plants producing less than 1000 m3/day; the costs to desalinate seawater are reported to be 0.44-1.62 USD/m3 for plants producing more than 12,000 m3/day
  • For thermal desalination, the costs are approximately 2-2.60 USD/m3 for 1000-1200 m3/day and 0.52-1.95 USD/m3 for plants producing more than 12,000 m3/day

Energy source

Energy should be sought from renewable sources, as fossil fuels, commonly used for such processes play against mitigation needs

Ease of maintenance

  • Requires continued maintenance of machinery
  • Requires continued improvements and updating of employed technology
  • Requires continued training for management and operations personnel

Technology performance

Already around 75 million people rely on desalinized water

Considerations

  • Further research into efficiency and sustainability of this approach is required as the process is energy consuming, expensive, and negatively impactful on ecosystems – advancements in the technology is improving the environmental and economic aspects of its implementation e.g. multi-stage flash (MSF) distillation is improving the energy efficiency of desalination; more durable polymer membranes, improved pre-treatment, and the use of devices for energy recovery have improved the costs and energy efficiency of reverse osmosis
  • The large scale, costs and management demands of desalination plants require collaboration between stakeholder groups including private organisations, government and users
  • The installation of a large plant can be incredibly disruptive to inhabitants of local areas and planning processes must therefore be transparent with any disruption being compensated for

Co-benefit, suitability for developing countries

  • Provides health and sanitation benefits, reducing disease and mortality
  • Provides employment opportunities in the local area
  • As populations grow and migration to coastal cities increases, this approach is expected to be more commonly utilised
  • The expense of construction, running and maintenance pose major challenges for developing countries
  • Use is particularly suitable in coastal or arid regions
  • Smaller scale, locally managed desalination technologies may be more appropriate

Information Resources

Climate Tech Wiki, n.d. Desalination. Available from: http://www.climatetechwiki.org/content/desalination [14 January 2015]

Freshwater, A. Desalination in Pacific Island Countries: A Preliminary Overview. SOPAC Technical Report 437. Available from: http://www.sopac.org/sopac/docs/SOPAC%20Technical%20Report%20437%20Desalination%20for%20Pacific%20Island%20Countries.pdf [14 January 2015]

UNFCCC, 2014. Background Paper on Technologies for Adaptation. Background Paper for the UNFCCC Technology Executive Committee (TEC) Workshop on Technologies for Adaptation. Bonn, Germany, 4 March 2014. Available from: http://unfccc.int/ttclear/misc_/StaticFiles/gnwoerk_static/events_workshops_adaptationtechs/f1b531ab99084107950d65c2c2de1d6d/d02425f42d614aa99c40fe39758b3ded.pdf [14 January 2015]

World Bank, 2004. Seawater and Brackish Water Desalination in the Middle East, North Africa and Central Asia. A Review of Key issues and Experience in Six Countries. Available from: http://siteresources.worldbank.org/INTWSS/Resources/Desal_mainreport-Final2.pdf [14 January 2015]