Scaling Up Solar Powered Desalination to Meet High Demand
As more and more cities are experiencing water shortages due to drought or because of their location in desert regions, governments are turning to desalination to meet the demand for water. Desalination is a process by which salt and other impurities are removed in order to produce clean water that can be use for drinking and for agriculture. Desalination, however, requires lots of energy to complete, and desalination plants gobble up fossil fuels only to eject heat absorbing gases into the environment. While desalination can be a solution to water shortages, it speeds up global climate change.
In response to these concerns, scientists and engineers are developing new, energy-efficient, and sustainable methods for transforming seawater for human consumption. Last week, scientists at MIT won the 2015 Desal Prize for designing a cost-efficient, solar powered desalination plant that can be used in areas with water shortages, especially in response to crises. The Desal Prize is administered by the United States Agency for International Development for innovations that help to solve water shortages in developing countries.
The MIT system uses solar panels to power an electrodialysis process that uses electric charges to separate salt and metals from water, and it does so efficiently enough that 90% of the salt water fed into the system is turned into drinking water. The MIT system can desalinate 2,100 gallons (7,950 liters) of water in 24 hours. Their system also relies on new membrane technology that allows for desalination to occur with far less energy than membranes used in conventional reverse osmosis systems, which are the most widely used systems for desalination.
The MIT process, while innovative, is still limited in scale. Cities that need to provide water for hundreds of thousands are even millions of people need solar powered desalination on a much greater scale. Saudi Arabia is attempting to do just that. The King Abdulaziz City of Science and Technology has hired a Spanish company. Abengoa, to build the world largest solar powered desalination plant. The plant will produce 60,000 cubic meters of water per day when starts operating in 2017. That is almost 16 million gallons of water per day.