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.

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