At 77, Matthys has just wrapped up a thesis for his Master’s degree and, in doing so, has contributed towards effective renewable energy solutions!
Stellenbosch, South Africa (10 December 2025) – Matthys de Wet didn’t return to Stellenbosch University (SU) to prove anything about age, but he’s done it anyway. That, and his research has looked at how biomass, like invasive alien trees, can be transformed into renewable energy.
At 77, he’ll graduate with a Master of Engineering, four decades after completing his undergraduate studies at the same institution. Matthys first completed his BSc and B.Eng degrees at Stellenbosch University in the 1970s and went on to build an extensive career in engineering.
After ‘retiring’ over a decade ago, he still kept on and started his company that specialises in renewable energy and techno-economic solutions for the agricultural sector.
Two years ago, he was approached by Prof Wikus van Niekerk, Dean of SU’s Engineering Faculty, to conduct a feasibility study for a 5 MW biomass-to-energy power station for Stellenbosch, in collaboration with the Centre for Renewable and Sustainable Energy Studies.
When the initial results showed that the cost of producing renewable electricity was too high to be competitive, Matthys decided to take the research even further and enrolled as a student again.
This time to complete his master’s using the project as the subject of his thesis.
Through this research, Matthys has focused on how biomass from invasive alien trees, old fruit trees and vineyards that would usually be burned as waste could instead fuel a renewable baseload energy solution.
According to SU, his research shows that a 5 MW system can consume up to 50,000 tonnes of woody biomass per year. This could effectively help reduce wildfire risks and support water security in river catchments, while emitting only CO₂ and water vapour.
Almost a decade after hitting retirement age, de Wet has managed to further his studies and contribute towards vital research that supports the environment through renewable energy!
Sources: Linked above
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