Seite - 6 - in Water, Energy, and Environment - A Primer

In recentyearsmucheffort hasgone into reducing thecostsof desalination, as its global importance has grown. Even though currently it only provides about 1% of the word’s drinking water, this fraction is growing steadily, and desalination is increasingly recognized as a reliable, drought-proof source of potablewater for coastal communities worldwide. Energy costs have been reduced by approximately 80% over the past two decades, and are projected to decrease byup to a further 60% in the next 20 years. These costs today range from 40 to 100US cents per cubic metre (1000 litres) of freshwater. Nevertheless, while ‘Today, the energy needed to produce freshwater from seawater for one household per year is less than that used by the household’s refrigerator’ (5), that cost is still higher, on average, than the cost of deriving freshwater fromgroundwater, water recyclingorwater conservation. The InternationalDesalinationAssociation (IDA) reports that worldwide at the end of 2015 there were more than 18,000 desalination plants in 150 countries, producing about 87million cubic metres of freshwater every day. About 44% of this capacity is located in theMiddleEast andNorthAfrica (MENA). It is estimated that more than 300million people currently rely ondesalinatedwater for someorallof theirdailyneeds. 1.4 DEMANDFORFRESHWATER Two important questions are: how is global demand for freshwater changing, and what are the implications when freshwater supplies are limited? Some people have identified access to freshwater as the 21st century’s analog to the burning issueof access to petroleumsupplies in the previous century. During the 20th century, global population tripled while the human demand for freshwater increased by a factor of six. That demand tripled in the past 50 years alone. Providing that much water has significant environmental impacts, which will be discussed in Chapter 4. Today, on average, a little over Water,Energy, andEnvironment–APrimer6