Revolutionizing Solar Power: Ultra-Black Nanoneedles Absorb 99.5% of Light for Next-Generation Solar Towers

A research team from the University of the Basque Country (EHU) has conducted a thorough analysis of ultra-black copper cobaltate nanoneedles to assess their solar energy absorption capabilities. The study revealed that these new nanoneedles exhibit exceptional thermal and optical properties, making them ideal for efficient energy absorption. This breakthrough opens up possibilities for concentrated solar power applications in the renewable energy sector.

The experiments were conducted in a specialized high-temperature research laboratory. The findings were recently published in the journal Solar Energy Materials and Solar Cells.

Concentrated solar power is emerging as a key player in the future of renewable energy due to its ability to store thermal energy effectively. While historically more complex and costly than photovoltaic power, recent advancements in concentrated solar power technology have made it more accessible. These systems are now being deployed in various countries as part of sustainable energy strategies.

Dr. Iñigo González de Arrieta, a researcher in the Thermophysical Properties of Materials group, emphasized the team’s focus on exploring ultra-black materials for solar tower applications. In these systems, solar energy is concentrated onto an energy-absorbing tower using mirrors.

Dr. González de Arrieta highlighted the importance of enhancing the efficiency of absorbing materials to improve the competitiveness of solar energy systems. The team utilizes cutting-edge equipment developed in their own lab to conduct thermo-optical analyses for measuring sample absorption properties, as high-temperature research facilities are limited globally.

The researchers at EHU analyzed the thermal and optical characteristics of patented copper cobaltate nanoneedles from the University of California San Diego. Dr. González de Arrieta noted that these nanoneedles outperformed carbon nanotubes traditionally used in such applications, especially when coated with zinc oxide.

Striving for Optimal Light Absorption

Solar tower plants rely on hundreds of mirrors to concentrate sunlight onto a focal point. Achieving maximum absorption on the tower requires ultra-black absorbing materials. While vertically aligned carbon nanotubes are currently the darkest available materials, they are not stable at high temperatures and humidity levels. Dr. González de Arrieta explained that despite absorbing about 99% of light, carbon nanotubes are unsuitable for solar towers.

The introduction of copper cobaltate nanoneedles represents a significant advancement in this field. These nanoneedles exhibit greater stability at high temperatures, with zinc oxide-coated variants surpassing the absorption efficiency of carbon nanotubes. While existing materials on solar towers absorb 95% of light, copper cobaltate nanoneedles achieve 99% absorption, rising to 99.5% with zinc oxide coating.

Collaboration between Dr. Renkun Chen of the University of California San Diego and the U.S. Department of Energy aims to deploy copper cobaltate nanoneedles coated with doped zinc oxide on solar towers. However, uncertainties in the current U.S. landscape could impact these plans.

Solar tower plants are operational in Andalusia and various desert locations worldwide. In Spain, only 5% of energy comes from this technology. Dr. González de Arrieta emphasized the importance of advancing renewable energy sources due to their environmental benefits and ability to store thermal energy for use during non-daylight hours.

Thermal energy absorbed by solar towers is stored by melting specific salts, which retain heat effectively and can be reintegrated into power grids when needed.

Dr. González de Arrieta stressed the ongoing need for developing new coatings with enhanced optical properties for solar tower applications. He also hinted at future explorations into coating nanoneedles with materials offering improved conductivity.