Los Angeles is a metropolis of 11 million people living in an area that recieved just 4 inches of rain in 2018. Desalination is one possible solution to this problem. A new plant’s proposed site sits just beneath the path of planes taking off from LAX, and just North of the coastal community of Manhattan Beach. The proximity to popular beaches, which regularly see over 130 million visitors, and the surrounding affluent neighborhoods, would not regularly preclude the building of an expensive freshwater producing facility. Necessity being the mother of invention, we have developed ways of extracting salt and other harmful impurities from Ocean water, making it safe for human consumption.
There are several ways to achieve this result. The proposed plant would use a technology called reverse osmosis, where water is pumped across membranes in an effort to remove salt. This is an energy intensive process, requiring 10x the energy versus just filtering freshwater alone, it also produces water that is extra salty. What happens to this brackish waste? This salty brine has to be disposed of, and it is pumped out to sea where it can disrupt marine ecosystems. There are people working on reusing or reducing wastewater, advances such as graphene and carbon nanotubes are on the horizon, but these technologies are not ready yet. The energy used to pump water through membranes, renewable energy could reduce these costs, and the price of disposal mean that water from Desalination plants is comparably more expensive than bringing fresh water in via aqueducts.
As the population of large cities increase, Los Angeles is estimated to have 17 million people by 2050, It will become increasingly necessary to secure more sources of water. More water will be needed to grow the food that will feed this growing population. In some places water is pumped out of the ground to satisfy demands, in drought years wells can run dry. While most of the planet is covered in water, 97% of it is undrinkable sea water. Desalination can be a reliable source of water for coastal cities, one that is not dependant on rain falling on far off mountains. This technology could help insulate populations of coastal cities from dependency on freshwater.
Human ingenuity may hold the solution to all of humanity’s problems, but there are always unforeseen consequences when it comes down to implementing various solutions. The benefits and consequences of something like a desalination plant have both an immediate impact and aftershocks that are not felt until many years later. One certainty is that the world population will continue to increase. That means more people will continue to live in places that need solutions to these increasing water demand. What are we going to do about it?
Author : Jeremy Brown