A team of scientists from Nanyang Technological University in Singapore has created a device to harvest daylight and relay it to underground areas.
In Singapore, authorities are looking at the possibility of creating deeper underground spaces for infrastructure, storage, and facilities. Therefore, demand for lighting is expected to increase in the future.
In order to create a daylight harvesting device to sustainably meet this demand, the team looked towards the magnifying glass, which can focus sunlight into one point.
They used an off-the-shelf acrylic ball, a single plastic optical fibre – a type of cable that carries a beam of light from one end to another – and computer chip-assisted motors.
The device sits above ground and, similar to the lens of a magnifying glass, the acrylic ball acts as the solar concentrator, allowing parallel rays of sunlight to form a sharp focus at its opposite side.
The focused sunlight is then collected into one end of a fibre cable and transported along it to the end that is deployed underground. Light is then emitted via the end of the fibre cable directly.
Simultaneously, small motors aided by computer chips automatically adjust the position of the fibre’s collecting end, to optimise the amount of sunlight that can be received and transported as the sun moves across the sky.
This daylight harvesting device was developed by Assistant Professor Yoo Seongwoo from the School of Electrical and Electronics Engineering and Dr Charu Goel, Principal Research Fellow at Nanyang Technological University’s The Photonics Institute, and the research was recorded in the peer-reviewed scientific journal Solar Energy.
The team is hopeful that the device will overcome the limitations of current solar harvesting technology. In typical solar concentrators, large, curved mirrors are moved by heavy-duty motors to align the mirror dish to the sun. The components in those systems are also exposed to environmental factors like moisture, increasing maintenance requirements.
This device has been designed to use the round shape of the acrylic ball, ridding the system of heavy-duty motors to align with the sun, and making it compact.
Asst Prof Yoo, lead author of the study said, “Our innovation comprises commercially available off-the-shelf materials, making it potentially very easy to fabricate at scale. Due to space constraints in densely populated cities, we have intentionally designed the daylight harvesting system to be lightweight and compact. This would make it convenient for our device to be incorporated into existing infrastructure in the urban environment.”