Can seawater filtering end the water crisis?

‘Water water everywhere, nor any drop to drink’, said Samuel Taylor Coleridge.

Today, one out of three people don’t have access to safe drinking water. Some projections will show by 2050, more than half our population will be living in water-stressed areas. That’s over four billion people. 

This question had baffled me since time immemorial and I have no idea why I did not ask this question during my Science class in school. 70% of the planet is covered in water and still, we are facing a water crisis?

We have advanced so much, then why can’t we simply filter the salty seawater for our consumption?

Well, it turns out that WE CAN. And countries like Saudi Arabia are already doing it. They have plenty of oil, but not water. They have the infrastructure and technology to filter seawater and use it for human consumption, even for drinking.

Desalination project in Saudi Arabia

So how can we do it?

The process of “filtering” seawater majorly involves desalination, i.e. removal of the huge amount of salt that the water contains. It starts with osmosis where we (say) push the water through a membrane under high pressure which leads to the separation of salts from the water.

The desalination process simplified

Simple, isn’t it?

So what is stopping us?

Filter that damn water and put an end to this “water shortage” once and for all!

But wait. Imagine if the whole world starts drawing out water from the sea, and starts filtering and using it, will the seawater finish one day? if so, how long will it take us to exhaust all the water in the sea?

Not-so-surprisingly, even if the whole world starts doing that, water in the ocean is not going “finish”. Firstly, if we estimate, the oceans have three hundred and sixty-six billion billion gallons of water. That’s over forty-eight billion gallons of water for every person on Earth. Secondly, there’s something called the water cycle, that we are forgetting, which will replenish the water through the rain.

Then why are we not doing it yet?

As exciting as it may sound, using seawater for our consumption is not the panacea for our problems. There obviously has to be a reason why this obvious sounding solution has not been widely adopted. And the primary reason is- ENERGY

It takes a lot of energy to desalinate the water.

Desalination is not an easy process and it requires a tremendous amount of energy to break up that bond between the water and salt. This energy, i.e. the electricity if coming from fossil fuels, will increase our carbon footprint. And if we bring it through renewables like solar and wind, it will need a huge initial investment in the infrastructure itself to match the exorbitant demand.

A solar powered desalination plant in Saudi. Though it is using clean solar energy, the cost factor still makes desalination an option for just the rich countries with no other alternative

Thus the cost increases!

Thus the desalinated water becomes too expensive! In Saudi Arabia, the water supply is heavily subsidized by the government and hence the public is able to afford it, but it is still more expensive than what people would pay for water in other parts of the world. The country was earlier importing water from neighboring regions. But in order to have an independent source of water, they turned to desalination.

Is it just the cost stopping us?

Along with clean water, the desalination process gives out a waste product called ‘brine’. Osmosis produces more brine than it produces clean water as an output. It is a highly concentrated saltwater solution, and we don’t know a proper way to deal with it yet. Hence it is mostly expelled back into the sea.

Many environmentalists have claimed that this could have a negative impact on marine life as the highly salted water would settle down on the ocean bed and harm the corals and all other aquatic plants and animals.

So is it a good idea?

May be not. It is energy intensive and expensive!

Water deficit places could use this as a solution to their water woes where they don’t really have an alternative to a reliable source of water. But at other places, solutions like reducing consumption and most importantly- careful and responsible consumption to reduce wastage should be opted.

Moreover, if we can desalinate the seawater, we can also treat the wastewater. That would be way more cost-efficient and environment friendly!

So, all in all, seawater desalination is not a panacea for our water woes. It sure is providing clean water to thousands of people right now, but its adaptation and expansion in the future would depend on the advancement of technology, making it cost, energy, and environment effective!
Till then- Reuse, Recycle and Reduce is our best bet!

Source- An amazing Youtube video by CNBC on ‘Can sea water desalination save the world’

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