A team of Nanyang Technological University, Singapore (NTU Singapore) researchers has designed a smart device to harvest daylight and relay it to underground spaces, reducing the need to draw on traditional energy sources for lighting.
In Singapore, authorities are looking at the feasibility of digging deeper underground to create new space for infrastructure, storage, and utilities. Demand for round-the-clock underground lighting is therefore expected to rise in the future.
To develop a daylight harvesting device that can sustainably meet this need, the team drew inspiration from the magnifying glass, which can be used to 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 just like the lens of a magnifying glass, the acrylic ball acts as the solar concentrator, enabling 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 with it to the end that is deployed underground. Light is then emitted via the end of the fibre cable directly. At the same time, small motors – assisted 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.
The device overcomes several limitations of current solar harvesting technology. In conventional 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.
The lead author of the study says their 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, they have intentionally designed the daylight harvesting system to be lightweight and compact. This would make it convenient for the device to be incorporated into existing infrastructure in the urban environment.
The team believes the device is ideally suited to be mounted as a conventional lamp post above ground. This would enable the innovation to be used in two ways: a device to harvest sunlight in the day to light up underground spaces, and a streetlamp to illuminate above ground at night using electricity.
The research by the scientists is an example of the university’s Smart Campus vision that aims to develop technologically advanced solutions for a sustainable future.
Moreover, a Singapore-based design-focused agency specialising in lighting, and the industry collaborator of the research study said that it is their privilege and honour to take this innovation journey with the developers. While they have the commercial and application knowledge, the developers’ in-depth know-how from a technical perspective has taken the execution of the project to the next level that is beyond expectations. Moving forward, the lighting company is exploring ways to potentially incorporate the smart device or its related concepts into its industrial projects for improved efficiency and sustainability.
Accordingly, reports say that Singapore’s focus on research and test-bedding is to improve the performance of solar systems and develop innovative ways of integrating solar energy systems into our urban environment.
As part of the country’s efforts to continually explore new options for energy supply and enhance our energy security, Singapore is exploring a variety of different options, including regional power grids, and emerging low-carbon alternatives such as low-carbon hydrogen and carbon capture, utilisation, and storage. While some existing technologies such as nuclear may not be viable today, we will continue to monitor the progress of nuclear energy technologies and build capabilities to better understand nuclear science and technology.
