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Study on solar energy compares well with current state-of-the-art research in the field

01 March 2024 | Story Leonie Bolleurs | Photo SUPPLIED

“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

Inaugural lecture: Prof Robert Bragg, Dept. of Microbial, Biochemical and Food Biotechnology

2006-05-17

Attending the inaugural lecture were in front from the left Prof Robert Bragg (lecturer at the Department of Microbial, Biochemical and Food Biotechnology) and Frederick Fourie (Rector and Vice-Chancellor). At the back from the left were Prof James du Preez (Departmental Chairperson: Department of Microbial, Biochemical and Food Biotechnology) and Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences). Photo: Stephen Collett

A summary of an inaugural lecture delivered by Prof Robert Bragg at the University of the Free State:

CONTROL OF INFECTIOUS AVIAN DISEASES – LESSONS FOR MAN?

Prof Robert R Bragg
Department of Microbial, Biochemical and Food Biotechnology
University of the Free State

“Many of the lessons learnt in disease control in poultry will have application on human medicine,” said Prof Robert Bragg, lecturer at the University of the Free State’s (UFS) Department of Microbial, Biochemical and Food Biotechnology during his inaugural lecture.

Prof Bragg said the development of vaccines remains the main stay of disease control in humans as well as in avian species. Disease control can not rely on vaccination alone and other disease-control options must be examined.

“With the increasing problems of antibiotic resistance, the use of disinfection and bio security are becoming more important,” he said.

“Avian influenza (AI) is an example of a disease which can spread from birds to humans. Hopefully this virus will not develop human to human transmission,” said Prof Bragg.

According to Prof Bragg, South Africa is not on the migration route of water birds, which are the main transmitters of AI. “This makes South Africa one of the countries less likely to get the disease,” he said.

If the AI virus does develop human to human transmission, it could make the 1918 flu pandemic pale into insignificance. During the 1918 flu pandemic, the virus had a mortality rate of only 3%, yet more than 50 million people died.

Although the AI virus has not developed human-to-human transmission, all human cases have been related to direct contact with infected birds. The mortality rate in humans who have contracted this virus is 67%.

“Apart from the obvious fears for the human population, this virus is a very serious poultry pathogen and can cause 100% mortality in poultry populations. Poultry meat and egg production is the staple protein source in most countries around the world. The virus is currently devastating the poultry industry world-wide,” said Prof Bragg.

Prof Bragg’s research activities on avian diseases started off with the investigation of diseases in poultry. “The average life cycle of a broiler chicken is 42 days. After this short time, they are slaughtered. As a result of the short generation time in poultry, one can observe changes in microbial populations as a result of the use of vaccines, antibiotics and disinfectants,” said Prof Bragg.

“Much of my research effort has been directed towards the control of infectious coryza in layers, which is caused by the bacterium Avibacterium paragallinarum. This disease is a type of sinusitis in the layer chickens and can cause a drop in egg product of up to 40%,” said Prof Bragg.

The vaccines used around the world in an attempt to control this disease are all inactivated vaccines. One of the most important points is the selection of the correct strains of the bacterium to use in the vaccine.

Prof Bragg established that in South Africa, there are four different serovars of the bacterium and one of these, the serovar C-3 strain, was believed to be unique to Southern Africa. He also recently discovered this serovar for the first time in Israel, thus indicating that this serovar might have a wider distribution than originally believed.

Vaccines used in this country did not contain this serovar. Prof Bragg established that the long term use of vaccines not containing the local South African strain resulted in a shift in the population distribution of the pathogen.

Prof Bragg’s research activities also include disease control in parrots and pigeons. “One of the main research projects in my group is on the disease in parrots caused by the circovirus Beak and Feather Disease virus. This virus causes serious problems in the parrot breeding industry in this country. This virus is also threatening the highly endangered and endemic Cape Parrot,” said Prof Bragg.

Prof Bragg’s research group is currently working on the development of a DNA vaccine which will assist in the control of the disease, not only in the parrot breeding industry, but also to help the highly endangered Cape Parrot in its battle for survival.

“Not all of our research efforts are directed towards infectious coryza or the Beak and Feather Disease virus. One of my Masters students is currently investigating the cell receptors involved in the binding of Newcastle Disease virus to cancerous cells and normal cells of humans. This work will also eventually lead to a possible treatment of cancer in humans and will assist with the development of a recombinant vaccine for Newcastle disease virus,” said Prof Bragg.

We are also currently investigating an “unknown” virus which causes disease problems in poultry in the Western Cape,” said Prof Bragg.

“Although disinfection has been extensively used in the poultry industry, it has only been done at the pre-placement stage. In other words, disinfectants are used before the birds are placed into the house. Once the birds are placed, all use of disinfectants stops,” said Prof Bragg.

“Disinfection and bio security can be seen as the ‘Cinderella’ of disease control in poultry. This is also true for human medicine. One just has to look at the high numbers of people who die from hospital-acquired infections to realise that disinfection is not a concept which is really clear in human health care,” said Prof Bragg.

Much research has been done in the control of diseases through vaccination and through the use of antibiotics. “These pillars of disease control are, however, starting to crumble and more effort is needed on disinfection and bio security,” said Prof Bragg.

Prof Bragg has been working in close co-operation with a chemical manufacturing company in Stellenbosch to develop a unique disinfectant which his highly effective yet not toxic to the birds.

As a result of this unique product, he has developed the continual disinfection program for use in poultry. In this program the disinfectant is used throughout the production cycle of the birds. It is also used to ensure that there is excellent pre-placement disinfection.

“The program is extensively used for the control of infectious diseases in the parrot-breeding industry in South Africa and the product has been registered in 15 countries around the world with registration in the USA in the final process,” said Prof Bragg.

“Although the problem of plasmid mediated resistance to disinfectants is starting to rear its ugly head, this has allowed for the opening of a new research field which my group will hopefully exploit in the near future,” he said.

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