The short answer is that it depends on what you compare it with. Desalinated water costs more than abstracting water from a river or borehole in an area with abundant resources, and less than having no water at all when the alternative is stopping production or restricting supply.<\/p>\n
As an isolated figure, the cost of desalinated water says little. What is useful is understanding what it is made up of and what drives it.<\/p>\n
Reverse osmosis separates water from salts by forcing it through a membrane at high pressure. That pressure has to overcome the osmotic pressure of seawater, and that is where the energy goes.<\/p>\n
As an order of magnitude, a modern seawater plant with energy recovery operates at a few kilowatt-hours per cubic metre produced. The exact figure depends on the salinity of the intake, the design recovery, the performance of the energy recovery system and the condition of the membranes.<\/p>\n
One important conclusion follows: the cost of desalinated water is tied to the price of electricity<\/strong>. When energy goes up, so does water.<\/p>\n It is also worth distinguishing seawater from brackish water. Desalinating a brackish borehole uses considerably less energy, because the starting salinity and the pressure required are much lower.<\/p>\n A large plant spreads investment and staff over a much larger volume and can use equipment with better specific performance. That is why large municipal plants produce water at a noticeably lower cost per cubic metre than small plants.<\/p>\n This does not mean a small plant is not worthwhile: its justification usually lies not in the price per cubic metre, but in having water available where there is none.<\/p>\n Desalinated water competes well when some of these conditions apply:<\/p>\n Some claims about desalination do not hold up. Desalination does not in itself increase rainfall or encourage vegetation, and no technology removes all the salts without producing a reject stream that has to be managed.<\/p>\n What has happened, and can be verified, is that specific energy consumption has fallen sharply over recent decades thanks to thin-film composite membranes and isobaric energy recovery devices. That improvement has made desalination viable in situations where it previously was not.<\/p>\n With the required flow and its distribution over the year, the salinity and variability of the intake, the required outlet quality, the brine destination and the energy price at the site. With that data, the full cost is calculated and compared with the real alternatives.<\/p>\n See the cost breakdown of desalinated water<\/a>, when desalination makes sense for industrial supply<\/a>, our desalination<\/a> solutions, or get in touch<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" It depends on what you compare it with and on site conditions. What really drives the cost of desalinated water and when it becomes competitive.<\/p>\n","protected":false},"author":1,"featured_media":5534,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[77],"tags":[],"class_list":["post-8325","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-desalination"],"acf":[],"_links":{"self":[{"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/posts\/8325","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/comments?post=8325"}],"version-history":[{"count":2,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/posts\/8325\/revisions"}],"predecessor-version":[{"id":10729,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/posts\/8325\/revisions\/10729"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/media\/5534"}],"wp:attachment":[{"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/media?parent=8325"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/categories?post=8325"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/keikengroup.com\/en\/wp-json\/wp\/v2\/tags?post=8325"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}What adds to the energy cost<\/h2>\n
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Why size lowers the cost<\/h2>\n
Where it is competitive<\/h2>\n
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What not to take for granted<\/h2>\n
How the question is answered for a specific project<\/h2>\n