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Desalination and Economy Prospects as Water Supply Methods

Författare:
Publiceringsår: 2010
Språk: Engelska
Sidor: 10
Dokumenttyp: Konferensbidrag
Förlag: ARWADEX

Sammanfattning

This paper discusses five major parameters in desalination, namely technology, raw-water, energy sources, cost and environmental effects. Both size and yield have grown rapidly in desalination plants due to high performance in technology developments in the last few years. Five different types of desalination technology are presented and bench-marked for long-term use: multistage flash evaporation (MSF), multiple effect evaporation (ME), vapour compression (VC), reverse osmosis (RO) and electrodialysis (ED). RO and MSF have for the last 30 years steadily been growing as the two major technologies and are presently producing about 87% of all desalinated water on a global scale. Especially RO has increased in popularity. In 1990, RO encountered for 31% of all desalination capacity, in 2001 it had 43% and today it has about 58% of all desalination capacity of the world.

Six different input water sources are used (seawater, brackish water, wastewater, rivers, brines and pure water). The proportions for different type of water sources seem to have almost the same percentages at least over the last 30 years. Saline raw water from the sea ranges from 56 to 65% of all feed waters and brackish waters ranges from 20 to 24% over the years. Gradually, wastewater seems to be more important, but in 2009 only 5% of all raw waters have their direct origin from wastewater systems. The potential in reusing wastewater is thus very large.

Energy is a key issue for desalination future. Increased desalination capacity means increased energy demand. Three different groups of energy supply have been analysed. At present, the cost of water produced from desalination using a conventional source of energy is lowest. The total fresh water production capacity has increased constantly and trebled from 1990 to 2001, and doubled from 2001 to 2009. The cost of desalination has decreased constantly from 1955 to 2009. Statistical analysis points indicates a cost less than US 0.5 $/m3 in 2020. This will probably continue to drop and reach US 0.35 $/m3 after year 2020. Wastewater is less costly to desalinate, approximately US 0.3 $/m3 from the year 2015. Brackish water, rivers and pure water will reach US 0.2 $/m3 at year 2015.

The environmental impact from water intake, energy need and brine discharge will be more and more important as the size of the desalination plants grow. Stricter regulations need to be addressed for these impacts. Also the land use, especially along the shores, is affected by the every larger desalination plants. New aspects of desalination will have to be solved when as much as 3 million cubic metres of brines water are discharges into the sea on a daily basis.

Disputation

Nyckelord

  • Technology and Engineering
  • Cost analysis.
  • Desalination
  • Water resources

Övrigt

ARWADEX-Water Desalination Conference in the Arab Countries
2010-04-11
King Faisal Conference Hall Riyadh, Kingdom of Saudi Arabia
Published
Yes

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