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01 March 2024 | Story Leonie Bolleurs | Photo SUPPLIED
Dr Lucas Erasmus
Dr Lucas Erasmus, Junior Researcher in the Department of Physics, has just returned from Belgium where he had his public defence of a joint PhD with Ghent University, titled: Luminescent solar concentrators – where Sm2+ doped phosphors shine.

“I like taking what I have learned from literature and going to the laboratory to test it. Sometimes the results surprise me, leading to additional experiments or refining. This process could continue for several months and even years, with me slowly building the puzzle. And finally, one day, all the pieces come together, and everything becomes very clear to me as a physicist. And if I am lucky, I will have the privilege of knowing a secret about nature that nobody else has known up to this point. However, as an innovator, I am tasked with using this new knowledge to develop ways to manipulate nature to deliver a helpful device.”

These are the thoughts of Dr Lucas Erasmus, Junior Researcher in the Department of Physics at the University of the Free State (UFS), who has just returned from Ghent, Belgium, where he had his public defence of a joint PhD with Ghent University, titled: Luminescent solar concentrators – where Sm2+ doped phosphors shine.

The research project is part of a bilateral collaboration between the Department of Physics at the UFS and the Department of Solid State Sciences at Ghent University. In this study, the strengths, experience, and resources of both research groups – experienced in developing luminescent materials for various applications – are used to ensure a stronger final product. To meet the requirements stipulated in the cooperation agreement between the two institutions for the joint supervision and certification of Dr Erasmus’ doctoral studies, research was conducted both at the UFS and at Ghent University.

Dr Erasmus’ research is significant in the light of rising energy prices, energy scarcity, and the pursuit of a carbon-free society, where there are strong incentives to develop new and renewable energy sources.

Combining windows and solar cells increase their relevancy in many applications

He says that although solar panels play an essential role in renewable energy – since they provide a route to directly convert solar radiation into electricity – there are limitations to installing conventional panels, which are bulky, rigid, and opaque. He believes that combining windows and solar cells could increase their relevance in the built environment, agricultural sector, and modern consumer electronics.

Explaining about the luminescent solar concentrator (LSC) in his study, he states that it is a device used as a large-area solar radiation collector that converts and emits radiation. The emitted radiation is directed to photovoltaic cells located in the small side area of the device. According to him, a basic LSC consists of a transparent waveguide with an embedded luminescent material and a strategically placed photovoltaic cell on the edge.

Dr Erasmus continues, “The large area of the waveguide collects a portion of the solar radiation, while the luminescent material absorbs the energy and downshifts it to longer wavelengths. Internal reflection directs the emitted photons towards smaller areas on the sides where the photovoltaic cells are used to convert the concentrated light into electricity.”

In his view, creating a large and efficient LSC is a challenging endeavour that requires an in-depth study of multiple domains. “This includes developing and optimising the luminescent material, studying its behaviour and the characteristics of the waveguide, and finally adding these two components and developing, characterising, and simulating the hybrid device,” he remarks.

“While the current prototype we have developed delivers good results, it is still far from perfect and not commercially viable,” he says, stating that this study could, however, serve as a guide for future researchers interested in developing LCSs. Dr Erasmus believes the underlying science behind the results contributes to a general understanding of the materials, making this study valuable to other fields and contributing to the larger body of science. At the end of the study, he also makes some recommendations for future research in this field. 

Study a reflection of theoretical knowledge and a practical system

The public defence consisted of both an internal and an external defence. The internal defence took place in January at the UFS between Dr Erasmus and the examination committee. The external defence occurred at Ghent University and was also open to the broader public. Also present at this event in Belgium were colleagues from the UFS – Prof David Motaung, an examiner; Prof Koos Terblans, co-supervisor; and Prof Hendrik Swart, supervisor for the PhD thesis.

Dr Erasmus’ experience of the oral examination was that the examiners were primarily positive in their critique but also thorough in their questioning. According to him, some of their remarks pointed out that they were impressed with the meticulous planning, execution, and interpretation of the experimental results and that the researchers involved ensured that any parameter that might have influenced the device was maximised. “Moreover, they liked the fact that I went all the way from theoretical knowledge to a practical system. The examiners also noted that the study compares well with the current state-of-the-art research in the field,” adds Dr Erasmus.

He says that having the public defence in Belgium was a once-in-a-lifetime experience, allowing him to interact and deliberate directly with the examiners and communicate their findings and conclusions to the broader public. Dr Erasmus hopes that this will lead to stronger collaboration and better public sentiment toward spending funding for scientific projects.

For future steps, he states, the research group involved in the project plans to continue this research by further increasing the device's efficiency. “To this end, we have already developed another luminescent material that can address some of the challenges we encountered while developing the first prototype device. This forms part of the work that Johané Odendaal is doing in her master’s degree, of which I am a co-supervisor. We also plan to enlarge the scope of our research to consider the challenges that are currently hampering the next generation of photovoltaic cells and to find ways in which we could address these issues,” comments Dr Erasmus.

News Archive

Shack study holds research and social upliftment opportunities
2015-02-10

Photo: Stephen Collett

When Prof Basie Verster, retired head of the Department of Quantity Surveying at the University of the Free State (UFS), initiated an alternative form of housing for Johannes - one of his employees - a decision was made to base research on this initiative. This research project in Grasslands, Heidedal focused on the cost and energy efficiency of green and/or sustainable shacks.

Esti Jacobs from the Department of Quantity Surveying, together with an honours student in Quantity Surveying, a master’s student in Architecture, and young professionals at Verster Berry, helped with the project.

The physical goals of the project were to create a structure that is environmentally friendly, and maintains a comfortable interior climate in winter and summer, as well as being cost-effective to erect. The structure also had to be socially acceptable to the family and the community.

“The intention was to make a positive contribution to the community and to initiate social upliftment through this project. Structures such as the ‘green shack’ may serve as an intermediate step to future housing possibilities, since these structures are relatively primitive, but have economic value and could be marketable,” she said.

Esti explains the structure of the building, which consists of gum poles and South African pine bearers, with a timber roof and internal cement block flooring. The building is clad with corrugated iron and has a corrugated iron roof finish. Additional green elements added to the structure were internal Nutec cladding, glasswool insulation in walls, internal gypsum ceiling boards with ‘Think Pink’ insulation, internal dividing wall and door, polystyrene in the floors, and tint on the windows. A small solar panel for limited electricity use (one or two lights and electricity to charge a cellphone) and a Jojo water tank for household consumption by the inhabitants were also installed.

Esti said: “Phase one of the research has been completed. This phase consisted of an investigation into the cost of an alternative form of housing structure (comparing traditional shacks with the planned structure) as well as the construction process of the physical housing structure.

“Phase two of the research, commencing in February 2015, will last for two to three years. This phase will include the installation of temperature and relative humidity logging devices inside the existing traditional shack and the new green shack. The logs will be regularly monitored by the UFS Department of Quantity Surveying and Construction Management.

These data will enable the researchers to measure the differences in comfort levels inside the two different structures. The data, together with other information such as building materials and methods, are then processed by software programs. Through the simulation of different environments, building materials, and alternate forms of energy, software models can be used to come up with conclusions regarding more energy-friendly building materials and methods. This knowledge can be used to improve comfort levels within smaller, low-cost housing units.

The UFS will be working with Prof Jeff Ramsdell of the Appalachian State University in the USA and his team on the second phase of the project.

“This research project is ongoing and will be completed only in a few years’ time,” said Esti.

The results of the research will be published in accredited journals or at international conferences.

 

For more information or enquiries contact news@ufs.ac.za.

 

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