Integrated system simultaneously harvests and stores solar thermal energy with low losses for 24/7 power under all conditions.
Researchers at the University of Houston have designed a device that efficiently captures solar energy and stores it for use by applications for the internet of things (IoT) and industrial IoT. Unlike solar panels and solar cells, which use photovoltaic technology for direct electricity generation, the hybrid device leverages the physics of molecular energy and the accumulation of latent heat to make the collection and storage of energy a 24/7 process, addressing a primary shortcoming of current solar products.
The researchers synthesized the device using norbornadiene-quadricyclane (NBD–QC), an organic compound with high specific energy and extended storage times, as the molecular storage material (MSM), separated from a localized phase-change material (L-PCM) by a silica aerogel to maintain the necessary difference in working temperature.
The common approach for storing solar energy is the use of batteries coupled with photovoltaic systems for both small- and large-scale installations. It is not only electricity that needs to be stored: An equally useful aspect of energy transition is the ability to capture and store solar thermal energy. That goal is not so easy to achieve, however, especially if you need a system that can preserve heat for long periods.
The challenge has spurred a new line of research in recent years that is devoted to the creation of solar storage on demand. The critical point of these systems remains efficiency. The Houston researchers’ development could thus drive decisive change in the thermal-battery sector.
Efficient harvesting and storage of solar thermal energy are essential to exploiting the abundant solar radiation that reaches Earth’s surface. Today’s systems use expensive materials with a high optical concentration, which leads to high heat losses.
The new device is based on a hybrid paradigm that uses daytime heat localization to provide 73% collection efficiency on a small scale and ∼90% on a large scale. In particular, at night, the energy stored by the hybrid system is recovered with 80% efficiency and at a higher temperature than during the day, setting it apart from other state-of-the-art systems, according to a paper published by the researchers in the December issue of Joule.