At 77 years old, Matthys Johannes de Wet is proof that learning has no age limit. This December he will cross the graduation stage at Stellenbosch University (SU) with a Master of Engineering in Industrial Engineering, a milestone that inspires students and professionals alike.

Matthys completed his BSc and B.Eng (Mechanical/Industrial) degrees at Stellenbosch University in the 1970s and went on to build an extensive career in engineering across Southern Africa, working at Iscor/Imkor Zinc in Namibia, Samancor Chrome Mines in Rustenburg, Sasol Mining in Secunda and later MBB Consulting Engineers in Stellenbosch. After retiring from MBB in 2010, he founded NRGen Advisors, specialising in renewable energy and techno-economic solutions for the agricultural sector.

In 2023, 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 (BtE) power station for Stellenbosch, in collaboration with the Centre for Renewable and Sustainable Energy Studies (CRSES). When the initial results showed that the cost of producing electricity was still too high to be competitive, Matthys decided to take the research further and turn the project into a master’s thesis under the supervision of Prof Joubert van Eeden. His re-configured design demonstrated that such a power station can generate electricity at a competitive cost of R2.80/kWh and achieve an internal rate of return of more than 16% as part of a proposed long-term Power Purchase Agreement.

His research highlights a powerful environmental opportunity. Biomass from invasive alien trees (IATs), along with old fruit trees and vineyards that are usually burned as waste, could instead fuel a renewable baseload energy solution. A 5 MW system can consume up to 50 000 tonnes of woody biomass per year, reducing wildfire risks and supporting water security in river catchments, while emitting only CO₂ and water vapour. The ash from the combustion chamber is environmentally friendly and is used as a soil ameliorant in agriculture.

Reflecting on his research journey, he credits his decades of engineering experience as essential to the study’s direction and relevance. His advice to others wanting to further their studies? “Becoming more familiar in your line of engineering, while working for a reputable employer will assist you to identify the gaps in the value chain, raw material logistics and the applicable technology in the field. This will provide you with a better understanding of your work and ultimately enable you to produce a thesis with practical application to industry,” he says. 

Prof van Eeden says Matthys is one of several later-career postgraduate students he has supervised. “I always enjoy the wealth of industry experience these candidates bring to the table. My role is simply to help shape and guide the research process, while benefiting from the insight gained along the way," he adds.

Matthys’ achievement highlights the value of lifelong learning and is an example of how experience and knowledge continue to drive innovation in the engineering industry.