UK seawater desalination may become necessary, says IMechE report

Seawater desalination may become necessary in the United Kingdom if precipitation does not provide sufficient water, according to a report Climate change: adapting to the inevitable published in February 2009 by the UK Institution of Mechanical Engineers.

The report is an attempt to get engineers to design now for what might happen over the next 100, 200 or even 1000 years.

On desalination, the report comments, “This is not a new technology but it is at present energy intensive. In a world where both energy and water are highly valued scarce resources, a balance may have to be struck as to the relative importance of energy and water levels. Energy-free solar desalination is a possibility although it is does require space, a commodity that may be equally as scarce as water or energy.”

Use of an increased spectrum of sources would lead to a more resilient supply, says the report, as each source will have a different response to variations in rain intensity. An increased reliance on locally collected water would also reduce demand from regional supplies, with developments being as close to a self-sufficient closed-loop system as possible.

On a local level, this was already being addressed with the installation of greywater recycling systems, says the report, recognising the fact that wastewater from one process could be sufficiently cleaned locally to be used as the source water for another process.

“The extension of this principle to include some of the national network could lead to a dual-purity grid,” the report forecasts, “where potable water is supplied only where it is needed and lower-purity water incorporating wastewater from certain processes is supplied to industry or for irrigation uses. Whilst this would be difficult to implement for the entire national distribution system, on a local level it would be easier, particularly if it is incorporated into new developments.”

The report draws attention to the reuse of wastewater on a large scale in Singapore, with grey- and black-water being put through an initial level of purification before being reintroduced into the reservoirs to be added to the potable water.