I was reading this yesterday, with some skepticism and incredulity, and wanted to find out if it’s actually possible. If it is and the claims are correct, then it can turn seawater and brackish water into potable for a little over 1c a liter, and “recovers approximately 95-97% of the fresh water from ocean desalination operations”.
It seems the method used is a mixture of warmth and centrifuge, and can be solar powered :eek:. The impact - if this isn’t a pie in the sky hoax - of this would be immense, far-reaching and a game changer. It could transform the coastlines of every dry state and country on the globe, refill depleted aquifers, be an enormous boost to the GDP of every area it goes to and possibly prevent some wars.
They say their (free) installation would take up 40’ by 60’ of space, provide 1,000,000 gallons of water per 24 hours and they’d only charge you for the water you consume. This seems outlandishly optimistic.
What they’re talking about based on their website seems to be a combination of reverse osmosis filtering, which is already in fairly wide usage, followed by evaporative distillation of the extremely salty water remaining. I don’t see any real theoretical problems with it, since it’s following a reasonably mature technology with significant waste but low energy coast with a more energy intensive but effectively waste free and very mature technology to improve overall effectiveness.
The problems that seem evident, however, are engineering and economic ones. Whether they can build one that functions as advertised, for the price advertised, is hard to say. If they have one built and it isn’t bleeding them dry, then I’m all for it. But you’d have to review the actual facility and financial documents to know if their claims are accurate.
The prices are not consistent, I grant you. On one site I read 1c/litre, on here, it says “Until now, the price of desalinated water projects has hovered around $8 a barrel, but the Dutch version comes in at around $1.50-$2.00 per barrel, or approximately $1,100-$1,350 per acre-foot of water.”
I know very little about water technology and the 1c/liter just struck me as good value. I wouldn’t know what an acre-foot was if I fell into it.
Imagine one acre of land covered with water to a depth of 1 foot. Or two acres covered with six inches of water. We’re used to a unit of volume combining three identical length units, e.g. cubic feet - but you can just as easily use three completely different length units, e.g. 1 cubic foot equals 30.48 foot-inch-centimeters - or you can use a unit of area combined with a unit of length, e.g. 1 acre-foot equals 1,233,481.84 liters.
At $1200 per acre-foot, that works out to a price of 0.1 cents per liter, quite a bit better than the 1 cent per liter you were citing in your OP.
You’re likely making your judgment from the cost of bottled water, which is hundreds to many thousands of times the cost of (already expensive, by some measures) residential water.
They seem to be using a heat pump methodfor reclaiming some of the energy used in the process in a previous process. Reducing the overall energy consumption. How effective this will scale up is still to be seen.
The link above, page 20, lists the steps:
Step 1: Saline water enters the DyVaR system by a feed pump.
Step 2: The recirculation loop is filled with the brine to be concentrated. It is heated by the recapturing of the carried energy through means of a recirculation pump, and heat energy is transferred via a heat exchanger.
Step 3: The brine is recirculated within the DyVaR during the concentration stage. Water in the brine is evaporated within the DyVaR modules thereby continuously increasing the concentration of the carried salts as a result.
Step 4: The fan maintains a slight under pressure in the DyVaR unit, this will decrease the boiling point of the brine as it circulates within the DyVaR recirculation loop. A lower boiling point creates a lower evaporation point, and also allows for a lower energy demand during the water evaporation process.
Step 5: The evaporated water (steam) is continuously transported by the fan to the heat exchanger. The compressor gives the steam extra energy as it is compressed.
Step 6: The compressed steam then passes the heat exchanger and condensates into liquid. During this condensation stage, the phenomena of exothermal energy will take place, and a huge amount of energy will be transferred via the heat exchanger back to the brine in the recirculation loop of the system.
Step 7: The salt concentration in the recirculation loop will increase until the desired concentration is reached (automatically measured). At that time a discharge valve is opened to release the highly concentrated brine and/ or salt crystals.
Step 8: The feed pump brings in new fresh brine to be concentrated, balancing the removal of concentrated brine of Step 7.
Step 9: A Solid Discharge Unit (SDU) is integrated within the brine discharge stream for the removal of crystals formed during the concentration process.
Remarks: The entire process is a continuous process. Salt crystals or concentrated 10# brine is discharged from the system continuously. The condensate, also leaving the DyVaR unit continuously, is of demineralized[water quality.
Thanks! That sort of makes sense to me now. I buy drinking water and pay $2.70 for 19 litres, so 14c a litre (which I think is very cheap for delivered ‘sweet’ water).
Could this process be made considerably cheaper by changing the value of what is considered acceptable for agricultural use or drinking? In other words using acceptable standards instead of highest standards.
It did, but I was concentrating on the acre of nearly knee-height water and not the calculations. I was imagining huge greenhouses in Africa, supplied by sea water, feeding tens of thousands of people, and huge golf courses with rich, lush greens :rolleyes:
For desalination: not much. The expensive part is not removing bacteria, it’s removing salt. Plants don’t like salt much either. In Israel, they do have some places where they grow salt-tolerant plants with water that has higher salt content, but it’s not something you can just do in general. You have to use specific species, and carefully monitor them.
