The Breakthrough of Ultrablack Nanoneedles in Solar Energy
At first glance, they resemble invisible needles , incredibly fine and slim — akin to a thousandth of a human hair. A team of Spanish researchers has achieved a significant breakthrough by developing ultrablack nanoneedles capable of absorbing up to 99.5% of solar radiation—a record-setting achievement that not only marks an optical milestone but also promises to enhance the efficiency of solar thermal plants.
Made in Euskadi
This impressive discovery originates from the Thermophysical Properties of Materials group at the University of the Basque Country (UPV/EHU) . The researchers have designed a surface made of copper cobaltate nanoneedles —a mixed oxide of copper and cobalt—with exceptional optical properties. This ultra-black material’s resistance to humidity and high temperatures renders it ideal for usage in solar tower receivers .
According to extensive testing, the material achieves an absorption rate of 99.5% of sunlight, surpassing notable materials such as black silicon (95%) and carbon nanotubes (99%). Researcher Íñigo González de Arrieta emphasized, “We are looking for ultrablack materials for more efficient solar towers,” highlighting the potential of these nanoneedles in the solar energy sector.
A Change for Solar Energy
In concentrating solar thermal power plants (CSP) , numerous mirrors reflect and concentrate sunlight towards a central tower. Here, the heat is employed to melt salts that store thermal energy, allowing for electricity generation even after sunset. The crux of this technology lies in maximizing each photon absorbed—should the receiver material reflect even a fraction of the light, that energy is wasted. This is precisely where the new nanoneedles shine.
Historically, black silicon has dominated this field with its 95% absorption efficiency . The new copper cobaltate nanoneedles have the potential to significantly enhance this percentage, increasing the competitiveness and profitability of solar thermal energy, particularly in sun-rich countries like Spain.
Beyond the Blackest Black
Carbon nanotubes previously seemed unbeatable—dark as a vacuum and capable of trapping nearly all light. However, they are fragile and deteriorate quickly when exposed to heat and humidity.
In contrast, the copper cobaltate nanoneedles developed by the Basque team can endure temperatures exceeding 700 degrees Celsius without sacrificing effectiveness. This stability translates to enhanced energy output and reduced maintenance requirements in solar tower applications, making them a more sustainable solution.
A Real Impact
Dr. Renkun Chen from the University of California, San Diego , is collaborating with the Basque team along with the U.S. Department of Energy to evaluate the feasibility of implementing these groundbreaking nanoneedles in industrial solar plants. Dr. Chen noted, “We observed that these nanoneedles performed better than the carbon nanotubes used until now, and that their performance increased when coated with zinc oxide .”
However, González de Arrieta also points out that challenges remain. Upcoming pilot-scale tests will help determine whether this technology is economically viable and capable of being produced on an industrial scale while retaining its impressive optical characteristics.
Darker, Brighter
The development of ultrablack nanoneedles illustrates the remarkable potential of nanotechnology in promoting global sustainability . The UPV/EHU team is committed to advancing this field by developing new compounds that exhibit superior thermal and optical conductivity, engineered to meet the demands of future solar towers.
Promoting renewable energy presents numerous benefits; it is completely clean and usable even when the sun isn’t shining, as González de Arrieta highlighted. If the research progresses successfully, the future of solar energy could paradoxically be darker than ever before.
Image | Flickr
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