Oceans of Water for Drinking?

A sheaf of reverse-osmosis membranes used to separate salt from water   Photo: Jamie Smith for The New York Times

With less than 1% of the water on Earth safe and available for human consumption, we are rapidly approaching a global water crisis — today,  one out of every three people does not have access to safe drinking water and by 2050, given climate change, that number is expected to be one out of two people.  Desalinization of ocean water is increasingly being looked at as an option for countries in the Middle East like Saudi Arabia and Israel, but only because they are able to afford the expensive and energy-intensive process.

Why This Matters:  At current prices, even wealthy countries like Saudi Arabia cannot afford to keep increasing the amount of water it puts through the desalinization process — given the increasing demand for drinking water, cheaper alternatives to the current process are desperately needed.  Like the Our Ocean Conference also discussed in today’s ODP, World Water Week, which was held last summer in Stockholm with 4000 participants (half of whom were under 35 years old) from 138 countries, facilitates the rapid global spread of ideas and best practices at a time when we need to accelerate action.  It could be that today events like World Water Week and the Our Ocean Conference are galvanizing the next wave of global conservation initiatives to solve the biggest challenges without needing global governing bodies to instigate action. Time will tell.

How Does Reverse Osmosis Work?

Yes, the process is called “reverse osmosis” and here is how it goes, according to The New York Times:

“four huge tanks full of sand filter impurities from the seawater as it arrives through a pipeline. Inside, the scream of pumps is deafening as the water is forced at up to 70 times atmospheric pressure into several hundred steel tubes, each stuffed like a sausage with spiral-wound membranes.

The microscopic pores in the membranes allow water molecules through but leave salt and most other impurities behind. Fresh water comes out of plastic pipes at the end of each tube.”

What Makes It So Hard To Scale?

In a word, cost.  Despite lots of research, scaling projects that meet the increasing demand has come slowly.  According to The Times, it has taken approximately 40 years to reach a maximum daily capacity of about 250 million gallons at the largest plants. But experts say to scale the technology yet again will take another 40 years, and there are “thermodynamic limits” on how much more efficient the process can get.  Moreover, right now, the energy cost is high and efforts to use renewable energy for desalination are still in their infancy.

Worthy of Your Time:  The full NYT Story here is an excellent deep dive into desalinization.

H/T to Friend of the Planet Dan A for providing ODP the scoop on World Water Week, which he attended this year.

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