China’s 2020 ambition to produce drinking water at 3 million m³day from desalination threatens to increase carbon emissions through increased use of largely coal-fired power generation according to the World Resources Institute (WRI). The institute said the energy penalty could be offset by some 75% by greater use of water reuse.
In its report on energy and water issues in the city of Qingdao, WRI warned that were the city to realise its aim to build 400,000 m³ in desalination capacity it’s greenhouse emissions could grow 80%. In contrast it pointed out that wastewater reuse consumed less than 1 kWh/m³ compared to 4kWh/m³ by desalination.
China’s coal-dominated power generation capacity meant that, “consuming greater amounts of desalinated water would simultaneously increase greenhouse gas emissions” said WRI in its report. “Until desalination technology becomes more energy efficient, it should only be used as a backup source of water in China,” according to the WRI.
The WRI estimated that close to 90% of China’s coastal cities faced water scarcity and some 300 million rural residents lacked access to clean water. In response the Chinese government was seeking to up the country’s designated water output to 3 million m³/d from 770,000 m³/day currently.
Magazine, Water and Wastewater International, reported a summary by consultant at Atkins Water and Environment International, Simon Spooner, of China’s policy: “When you consider the energy requirement of desalination and the problems in supplying that energy, in terms of resource consumption and carbon emissions, then that’s really looking quite problematic. The whole Chinese desalination journey seems to be getting a bit shaky as well. Some of the plants that have already been built have got problems they are looking into.”