Introduction
Virtually everything we do affects our ability to harness and expend energy. One simple, small-scale
example is the energy expended by our bodies to fight the effect of gravity as salts and impurities are
removed from our body. On a much larger scale, energy is necessary to meet the needs of society, which
include obtaining, transporting, treating, and distributing potable water.
Access to clean, safe, and reliable sources of drinking water is a basic goal in today’s world. As society has
developed, so has our ability to transport water over great distances to meet that fundamental objective, as
well as the ability to measure the quality of water to ensure that it is safe to drink. To a large extent, the
advent of analytical techniques to measure contaminants, viruses, and pathogens in water paved the way
for the US Environmental Protection Agency (US EPA) in the early 1970’s to develop rules and regulations
requiring drinking water to be treated, or “manufactured”, to meet standards for the benefit and protection of
public health. Rules and regulations have evolved since the 1970’s, commensurate with our understanding
of contaminants and ability to measure them. This “evolution” of standards led the US EPA to identify
membrane filtration – including reverse osmosis desalination – as one treatment technology for drinking
water supplies to meet increasingly difficult water quality challenges.
Today, virtually every drinking water supply is treated in some form or fashion, driven by a number of
factors primarily associated with the discovery of new contaminants: advanced testing methods; public
perception; verifiable health risks; and development of improved/new water quality standards. The extent of
water treatment – and the energy and power needed to meet those requirements – can vary considerably,
as expected, because of the accessibility and initial quality of a raw water supply.
Seawater desalination, like any other water treatment technology or separation processes, requires the use
of energy to produce water. As a drinking water treatment technology, however, seawater desalination
requires more energy than most other water treatment methods. Often, however, the power consumption
associated with seawater desalination is exaggerated or inaccurately represented, particularly when
compared to other treatment technologies or alternatives assuring safe, reliable public water supply.
This paper reviews and outlines the power requirements associated with seawater desalination, measures
used to compare and offset seawater desalination power consumption to other water supply alternatives,
and the opportunities for future reduced energy demand.