Water from Air ? Or from Sea ?

 

 

Dear Shri Aditya Thackerayji

( adityathackeray@me.com )

 

From news reports , I believe you have directed government officers to prepare a report on setting up a 200 MLD desalination plant on Gorai coast

While appreciating your concern, I urge you to direct the officers concerned to go through this email in order to determine :

Ø  Availability of FUNDS ( Capital Cost ) required for an RO plant

Ø  Operating costs to produce 1 litre of drinking water

Ø  Time ( years ) for construction

Ø  Availability of  a cheaper alternate technology ( eg : water from air, using solar power )

With regards,

Hemen Parekh  /  hcp@RecuitGuru.com  /  30 Oct 2020

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Context :

BMC revives plan to set up desalination plant for potable water   /  27 Oct 2020

Extract :

Ø     Later in 2016-17, the BMC had initiated the process to set up two desalination plants….However, later, the project was put on hold due to high cost.

Ø     P Velrasu, additional municipal commissioner (AMC), BMC, said, “The cost for a desalination plant has been optimised because of evolution of technology. The cost of construction of the plant is the same as that of a dam. It is estimated to cost around Rs 1,800 crore to construct a 200 MLD plant.”

Ø     The civic body supplies 3,750 million (m) litres (l) of water daily, as compared to the demand of 4,200 ml.

Ø     Initially, a pilot project will be undertaken, which will cater to 5% of Mumbai’s drinking water needs, and later the capacity will be successfully augmented to 200 MLD  { 200 / 4200 = 4.76 %  !  }

Ø     “An Israeli company has been tasked to submit the feasibility report, which was involved in a similar 650 MLD-capacity plant in Israel. It will take around three years to construct the plant,” said Velrasu.

Ø     Dubai is the first city in the world to construct a desalination plant.

Ø     Chennai, which has three such plants, had constructed its first project in 2003 that supplies 90 MLD of water to the city.

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Context :

Solar System Can Pull Drinkable Water Directly From The Air  /   14 Oct 2020

 

Extract :

Ø     By contrast, the new system can work at humidity levels as low as 20 percent and requires no energy input other than sunlight or any other available source of low-grade heat.

 

Ø     The present production rate of about 0.8 liters of water per square meter per day may be adequate for some applications, 

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My earlier blog / email on this technological break-through :

 

Water above our heads ………………………………………………….. [ 29 Mar 2019 ]

 

Extracting Water from Air : Now Electricity from Air ?......[ 18 Feb 2020 ]

 

Water Water Everywhere ? Even in Latur ?               [ 15 April 2017 ]

 

Deja Vu ?                                                                     [ 28 Feb 2018 ]

 

Indian Water  Warriors  ?                                                [ 24 Mar 2018 ]

 

Water Wars Are Looming !                                            [ 09 June 2018 ]

 

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Here is what Gujarat had planned 2 years ago :

A Desperate Measure ? ………………………………………………………  [ 18 Nov 2018 ]

 

Extract :

Using Reverse Osmosis technology, plant will produce 100 million liter of drinkable water per day [ 100 MLD ]

  

At what cost ?

 

My guesstimate :

 

 Capital Cost   ……………………………….. Rs   1,000  cr

 

Interest @ 15 %  ………………………….. Rs    150  cr

 

Depreciation @ 10 %..................... Rs    100  cr

 

Operating Expenses @ 20 %  ………… Rs    200  cr

 

Total annual cost ……………………………  Rs    450  cr

 

Per day cost ( 365 days ) ………………. Rs  1.23   cr  (  Rs 12.3 Million )

 

 

 So , per liter cost …………………………… Rs  0.10  ( approx. )

 

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NOW STUDY THIS REPORT :   The Cost of Desalination

 

Extract :

 

Ø     The  average costs, represented by the best fit line in the data shown, are

       about

 

       >    $ 0.70/m3 ($2.65 per thousand gallons = approx.. Rs 0.05 / litre )

              for very large plants (325,000 m3/day) and rise to

 

               

 

       >    $ 1.25/m3 ($4.75 per thousand gallons) for small plants (10,000

             m3/day). 

 

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Find “ per litre cost of desalination “ of several plants around the world , at :

https://www.researchgate.net/figure/Exceptional-Cost-Efficiency-of-Israels-Desalination-Facilities_fig1_263468292

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As to the desalination plants of Chennai , here are some interesting facts :

Rs 1.36 crore a day for just 200 million litres of water; can Chennai really afford desalination plants?( 07-03-2019)

 

{ ie: 6.8 paise per litre }

 

Data shared by Chennai Metrowater Supply and Sewerage Department (CMWSSD) specifies the breakup of the expenditure on various modes of procuring water as in the table below:

Source	Capital Cost per MLD (in Rs)	O & M Cost per MLD (in Rs)
Desalination plants	15.30 crores	68,000
Surface Water resources	7.70 crores	6000-23,000 (average of 14,500)

 

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