Nanoparticles can triple the rate of evaporation for solar desalination

Tellurium nanoparticles can triple the evaporation rate of solar desalination and can raise the temperature of water from 29° to 85°C within 100 seconds.

If the production of Tellurium nanoparticles can be scaled up to commercial scale the energy needed for desalination can be reduced by 10 times.

There are already several industrial-scale solar desalination projects being built in Israel and Saudi Arabia. Those systems are not using nanoparticle enhancement. The Israel project will produce 10,000 tons of desalinated water per day.

In June 2015, the International Desalination Association reported 18,426 desalination plants operated worldwide, producing 86.8 million cubic meters per day, providing water for 300 million people. This was a 10.71% increase in 2 years. The single largest desalination project is Ras Al-Khair in Saudi Arabia, which produced 1,025,000 cubic meters per day in 2014. Kuwait produces a higher proportion of its water than any other country, totalling 100% of its water use.

Desalination costs in 2013 ranged from US$0.45 to $1.00/cubic meter. More than half of the cost comes directly from energy cost.

Having ten times lower energy costs could bring the cost of desalination to 0.25 per cubic meter.

Science Advances – The optical duality of tellurium nanoparticles for broadband solar energy harvesting and efficient photothermal conversion

Nanophotonic materials for solar energy harvesting and photothermal conversion are urgently needed to alleviate the global energy crisis. Researchers demonstrated that a broadband absorber made of tellurium (Te) nanoparticles with a wide size distribution can absorb more than 85% solar radiation in the entire spectrum. Temperature of the absorber irradiated by sunlight can increase from 29° to 85°C within 100 seconds. By dispersing Te nanoparticles into water, the water evaporation rate is improved by three times under solar radiation of 78.9 mW/cm2. This photothermal conversion surpasses that of plasmonic or all-dielectric nanoparticles reported before. They also establish that the unique permittivity of Te is responsible for the high performance. The real part of permittivity experiences a transition from negative to positive in the ultraviolet-visible–near-infrared region, which endows Te nanoparticles with the plasmonic-like and all-dielectric duality. The total absorption covers the entire spectrum of solar radiation due to the enhancement by both plasmonic-like and Mie-type resonances. It is the first reported material that simultaneously has plasmonic-like and all-dielectric properties in the solar radiation region. These findings suggest that the Te nanoparticle can be expected to be an advanced photothermal conversion material for solar-enabled water evaporation.

57 thoughts on “Nanoparticles can triple the rate of evaporation for solar desalination”

  1. I’m a little skeptical of this report. Or rather of its significance. The typical evaporation rate of water in open ponds is already fairly close to what you’d get if 100% of the energy of incident sunlight were absorbed for production of water vapor. A suspension of tellurium nanoparticles that made the water a perfect absorber for the solar spectrum with a low emittance for long wave thermal IR would make a difference, but nowhere near 3x. Of course this isn’t about open ponds; it’s about closed boxes where the evaporated water vapor is condensed and recovered. But I don’t think that makes much difference. We’ve long had thin film window coatings that are transparent across the main solar spectrum, but highly reflective (and hence minimally emissive) at thermal IR wavelengths. And simple black slats in the water below the cover will serve to minimize direct reflectance of the solar spectrum. There’s no thermodynamic headroom for a 3x performance improvement.

  2. I’m a little skeptical of this report. Or rather of its significance. The typical evaporation rate of water in open ponds is already fairly close to what you’d get if 100{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the energy of incident sunlight were absorbed for production of water vapor. A suspension of tellurium nanoparticles that made the water a perfect absorber for the solar spectrum with a low emittance for long wave thermal IR would make a difference but nowhere near 3x.Of course this isn’t about open ponds; it’s about closed boxes where the evaporated water vapor is condensed and recovered. But I don’t think that makes much difference. We’ve long had thin film window coatings that are transparent across the main solar spectrum but highly reflective (and hence minimally emissive) at thermal IR wavelengths. And simple black slats in the water below the cover will serve to minimize direct reflectance of the solar spectrum. There’s no thermodynamic headroom for a 3x performance improvement.

  3. Tellurium is an expensive rare earth which should not be blended with throw away concentrated salt water. Tellurium and nanoparticles are also toxic and should not be released into the environment. I can only conclude this is a poorly written article. Evaporation rate depends not on tellurium concentration in the solution but energy input. Please use scientifically literate writers!

  4. Tellurium is an expensive rare earth which should not be blended with throw away concentrated salt water. Tellurium and nanoparticles are also toxic and should not be released into the environment. I can only conclude this is a poorly written article. Evaporation rate depends not on tellurium concentration in the solution but energy input. Please use scientifically literate writers!

  5. I assume they will either want to recover the Tellurium or so little is required that it does not matter. It might be that if you allow highly concentrated salt water with the Tellurium to dry in the sun that the salt crystals that result will not include the Tellurium in the lattice. If that is the case, then you just need to grow the crystals fairly large and then rinse them quickly. The rinse can then be reused, and most of the crystallized salt discarded.

  6. I assume they will either want to recover the Tellurium or so little is required that it does not matter.It might be that if you allow highly concentrated salt water with the Tellurium to dry in the sun that the salt crystals that result will not include the Tellurium in the lattice. If that is the case then you just need to grow the crystals fairly large and then rinse them quickly. The rinse can then be reused and most of the crystallized salt discarded.

  7. If you’re doing RO, run it dynamically based on real time day ahead price signals from the utility. Many offer rates down to 3c/kWh under this structure. If you doing thermal desalination, integrate with a steam cycle generator. 60-70% of the energy that goes into a steam cycle (from a nuclear or coal boiler) ends up being used to evaporate water.

  8. Quite right. All the energy going into a closed box has to go somewhere, and once reflection and IR retransmission are cut off, it has to go into heat

  9. What is going on in a closed box can make a difference. Consider that the water changes phase twice, once in evaporation and once in condensation. So net energy is zero. If more of the energy given off during the condensation step is recovered, system efficiency can go way up. There is a reduction in entropy because you get a more ordered result (pure water rather than mixed with salt), and that does require energy, but as par as the physics is concerned, it is not much compared to the energy to change the phase.

  10. If you’re doing RO run it dynamically based on real time day ahead price signals from the utility. Many offer rates down to 3c/kWh under this structure.If you doing thermal desalination integrate with a steam cycle generator. 60-70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the energy that goes into a steam cycle (from a nuclear or coal boiler) ends up being used to evaporate water.

  11. Quite right. All the energy going into a closed box has to go somewhere and once reflection and IR retransmission are cut off it has to go into heat

  12. What is going on in a closed box can make a difference. Consider that the water changes phase twice once in evaporation and once in condensation. So net energy is zero. If more of the energy given off during the condensation step is recovered system efficiency can go way up. There is a reduction in entropy because you get a more ordered result (pure water rather than mixed with salt) and that does require energy but as par as the physics is concerned it is not much compared to the energy to change the phase.

  13. Where will all this brine go that already is a mayor liability for existing desalination facilities??? There is no free ride here.

  14. Interesting – Install this over existing sea salt collection basins and it improves their margin while also helping their nearby communities.

  15. Where will all this brine go that already is a mayor liability for existing desalination facilities??? There is no free ride here.

  16. Interesting – Install this over existing sea salt collection basins and it improves their margin while also helping their nearby communities.

  17. (eye roll) Just perfect. More Un-filterable nano particles that can polute the water, only these ones will make the water everywhere much too hot for plants, people, and animals of all kinds. Please try again.

  18. (eye roll)Just perfect. More Un-filterable nano particles that can polute the water only these ones will make the water everywhere much too hot for plants people and animals of all kinds. Please try again.

  19. But it would require far more solar energy to dry out your concentrated brine that you are saving with this technology in the first place.

  20. But it would require far more solar energy to dry out your concentrated brine that you are saving with this technology in the first place.

  21. Perhaps the Te brine could be used to boost the process without being in direct contact with the water to be desalinated, or it’s brine. Disposing of the nanoparticulate in the brine is the big drawback.

  22. Perhaps the Te brine could be used to boost the process without being in direct contact with the water to be desalinated or it’s brine. Disposing of the nanoparticulate in the brine is the big drawback.

  23. I think the concept of Te-NP application for Desalination is in very primitive stage and still a lot has to be done and investigated.

  24. I think the concept of Te-NP application for Desalination is in very primitive stage and still a lot has to be done and investigated.

  25. Perhaps the Te brine could be used to boost the process without being in direct contact with the water to be desalinated, or it’s brine. Disposing of the nanoparticulate in the brine is the big drawback.

  26. (eye roll)
    Just perfect. More Un-filterable nano particles that can polute the water, only these ones will make the water everywhere much too hot for plants, people, and animals of all kinds.
    Please try again.

  27. If you’re doing RO, run it dynamically based on real time day ahead price signals from the utility. Many offer rates down to 3c/kWh under this structure.

    If you doing thermal desalination, integrate with a steam cycle generator. 60-70% of the energy that goes into a steam cycle (from a nuclear or coal boiler) ends up being used to evaporate water.

  28. Quite right. All the energy going into a closed box has to go somewhere, and once reflection and IR retransmission are cut off, it has to go into heat

  29. What is going on in a closed box can make a difference. Consider that the water changes phase twice, once in evaporation and once in condensation. So net energy is zero. If more of the energy given off during the condensation step is recovered, system efficiency can go way up. There is a reduction in entropy because you get a more ordered result (pure water rather than mixed with salt), and that does require energy, but as par as the physics is concerned, it is not much compared to the energy to change the phase.

  30. I assume they will either want to recover the Tellurium or so little is required that it does not matter.

    It might be that if you allow highly concentrated salt water with the Tellurium to dry in the sun that the salt crystals that result will not include the Tellurium in the lattice. If that is the case, then you just need to grow the crystals fairly large and then rinse them quickly. The rinse can then be reused, and most of the crystallized salt discarded.

  31. Tellurium is an expensive rare earth which should not be blended with throw away concentrated salt water. Tellurium and nanoparticles are also toxic and should not be released into the environment. I can only conclude this is a poorly written article. Evaporation rate depends not on tellurium concentration in the solution but energy input. Please use scientifically literate writers!

  32. I’m a little skeptical of this report. Or rather of its significance. The typical evaporation rate of water in open ponds is already fairly close to what you’d get if 100% of the energy of incident sunlight were absorbed for production of water vapor. A suspension of tellurium nanoparticles that made the water a perfect absorber for the solar spectrum with a low emittance for long wave thermal IR would make a difference, but nowhere near 3x.

    Of course this isn’t about open ponds; it’s about closed boxes where the evaporated water vapor is condensed and recovered. But I don’t think that makes much difference. We’ve long had thin film window coatings that are transparent across the main solar spectrum, but highly reflective (and hence minimally emissive) at thermal IR wavelengths. And simple black slats in the water below the cover will serve to minimize direct reflectance of the solar spectrum. There’s no thermodynamic headroom for a 3x performance improvement.

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