Global Production of Desalinated Water
Table 1 provides figures for the global production of desalinated water, by process and plant capacity. It shows that MSF plants have a higher total production capacity than any other process, despite the larger number of reverse osmosis plants. The growth and development of MSF plants owes a tremendous debt to the seminal contributions of the late Professor R. Silver of Glasgow University, who was the foremost pioneer of industrial scale distillation units. His first large-scale MSF units, in Kuwait and in Guernsey, were both commissioned in 1960. These plants had 19 and 40 stages respectively. Table 1 shows that, of the larger desalination plants (>4000 m3 d-1), MSF plants amount to 64 per cent of the total capacity.

Table 1. Summary of worldwide desalination capacity to 1998, split by plant type and process capacity range.

Desalting process

Percentage

Capacity (106 m3 d-1)

Capacity
(106 gal d-1)

No. of plants

Unit capacity        
100-60 000 m3 d-1        
Multistage flash 44.4 10.02 2204 1244
Reverse osmosis 39.1 8.83 1943 7851
Multiple effect 4.1 0.92 202 682
Electrodialysis 5.6 1.27 279 1470
Vapor compression 4.3 0.97 213 903
Membrane softening 2.0 0.45 99 101
Hybrid 0.2 0.05 11 62
Others 0.3 0.06 13 120
  100.0 22.57 4965 12 433
Unit capacity        
500-60 000 m3 d-1        
Multistage flash 46.8 10.00 2200 1033
Reverse osmosis 37.9 8.10 1782 3835
Multiple effect 3.8 0.81 178 653
Electrodialysis 4.7 1.00 220 230
Vapor compression 4.2 0.90 198 486
Membrane softening 2.1 0.45 99 64
Hybrid 0.2 0.04 9 27
Others 0.23 0.05 11 11
EDI 0.05 0.01 2 97
  100.0 21.36 4699 6436
Unit capacity        
4000-60 000 m3 d-1        
Multistage flash 64.0 9.27 2039 496
Reverse osmosis 25.7 3.72 818 613
Multiple effect 3.6 0.52 114 48
Electrodialysis 2.1 0.31 68 60
Vapor compression 1.9 0.28 62 42
Membrane softening 2 0.36 79 50
Hybrid 0 0.02 4 2
Others 0 0.00 0 0
  100.0 14.48 3186 1311

Source: 1998 IDA Wordwide Desalting Plants. Inventory Report No. 15. Wangnick Consulting GmbH.

Table 2 splits the data in a different way to indicate the disproportionately large share of the world's desalination capacity which is in the Arab states, and particularly in the Arabian Gulf.

Table 2. Summary of worldwide desalination capacity, to 1998 showing contribution made by Arab nations.

Desalting process

% of total world capacity

Capacity
(106 m3 d-1)

Capacity
(106 gal d-1)

Global      
Multistage flash 44.4 10.02 2204
Reverse osmosis 39.1 8.83 1943
Multiple effect 4.1 0.92 202
Electrodialysis 5.6 1.27 279
Vapor compression 4.3 0.97 213
Membrane softening 2.0 0.45 99
Hybrid 0.2 0.05 11
Others 0.3 0.07 15
  100.0 22.58 4968
Arab States      
Multistage flash 37.6 8.50 1870
Reverse osmosis 12.0 2.70 594
Multiple effect 0.5 0.12 26
Electrodialysis 1.6 0.35 77
Vapor compression 1.6 0.36 79
Membrane softening 0.0 0.00 0
Hybrid 0.0 0.01 2
Others 0 0 0
  53.3 12.04 2649
AGCC States      
Multistage flash 35.0 7.90 1738
Reverse osmosis 9.1 2.05 451
Multiple effect 0.2 0.05 11
Electrodialysis 0.5 0.12 26
Vapor compression 1.0 0.22 48
Membrane softening 0 0 0
Hybrid 0 0 0
Others 0 0 0
  45.8 10.34 2275

AGCC = Arabian Gulf Co-operation Council.
Source: 1998 IDA Wordwide Desalting Plants. Inventory Report No. 15. Wangnick Consulting GmbH.