A team from Stellenbosch University’s Faculty of Engineering has developed and successfully tested South Africa’s first electric minibus taxi, Daily Maverick reports.

South Africa’s electric vehicle (EV) industry lags behind those of many other countries amid the global race to move to clean energy in the transport sector. The Stellenbosch University (SU) team has set out to prove that it is feasible to electrify taxis by retrofitting an existing internal combustion engine (ICE) with an electric motor and battery.

Their pilot project, in partnership with Oxford University and a local mining equipment manufacturer, Rham Equipment, was sponsored by the South African National Energy Development Institute (SANEDI), writes the Daily Maverick.

According to Professor Thinus Booysen of the Department of Industrial Engineering at SU, South African manufacturers now have a small window to open more plants to create electric vehicles.

“Remaining in the slow lane of the electric vehicle transition could put thousands of jobs at risk,” said Booysen. “The automotive industry and our government cannot afford to be asleep at the wheel.”

As the Daily Maverick previously reported, while the world accelerates its transition to EVs, with 14% of all cars sold worldwide in 2022 being electric, South Africa only has about 2,300 EVs among a total of about 12 million passenger vehicles on the road.

South Africa’s transport sector is the second-biggest polluter after the power industry, accounting for 13% of CO₂ emissions, with road transport accounting for 91.2% of these transport emissions. South Africa exports two-thirds of its vehicles to EV-focused Europe.

However, the EV-manufacturing industry in the country is non-existent. Booysen and his team of researchers at the SU see their pilot project as a stepping stone for the lagging EV industry in Africa’s most advanced economy.

“More than 70% of the trips in South Africa are by minibus in the informal sector, which is why we are hoping to encourage the retrofitting of some of the 250,000 minibuses in the country with electric propulsion. These will be cheaper and much more environmentally friendly than new electric vehicles,” Booysen explained.

“With this venture, we want to help build the skills that will be needed to manufacture electric vehicles locally and also create awareness about how much we could save with electric taxis,” he added.

Design challenges

One of the team members, Stephan Lacock, explained that the engineers removed the minibus’ ICE and all other associated components, including the petrol tank, manual transmission, gas pipe, and radiator.

“Overcoming design challenges, Rham Equipment and our research team have successfully created a reproducible ‘kit’ that includes the main components of the electric powertrain or system that propels the vehicle forward,” Lacock said.

“These include an electric motor, inverter, charger, electronic control unit, and a single-speed reduction gearbox. The powertrain is skilfully connected to a custom-designed battery pack that meets the specific operational needs of a minibus.”

Instead of a manual gearbox, the EV taxi has a single-speed gearbox and vehicle control unit which was 3D-printed at the Rham Equipment workshop and is more energy efficient.

Lacock explained that “retrofitting is actually a lot cheaper than building an EV from scratch, because you only need to buy the electric motor, inverter and batteries.” It is definitely cheaper than buying a new EV, he said, because an EV would have to be imported. Also, retrofitting has a far smaller carbon footprint, because emissions will not be created in the manufacture of a new frame and chassis.   

According to Lacock, the new minibus has an advanced regeneration system that harnesses energy generation during deceleration and downhill driving, improving the vehicle’s energy efficiency and overall range.

“As a result, the minibus is now equipped to travel an estimated range of approximately 120 km, with a maximum speed of 120 km/h. It has an electric motor power of 90 kW and a battery capacity of 53.76 kWh,” Lacock said.

“This ensures that it meets all load and driving requirements comparable to those of traditional internal combustion engine minibuses. Moreover, the electric powertrain brings enhanced agility and an exhilarating driving experience to the minibus.”

Grid constraints

Despite being optimistic about the retrofitting of taxis, Booysen said that employing them could be challenging due to the country’s energy crisis, BusinessTech reports.

“We need to look at what the impact would be if we add an extra load of electric vehicles to the grid,” Booysen explained, adding that there were over 250,000 taxis in South Africa that would be of particular concern to grid load when electric.

A 2022 study co-authored by Booysen found that to avoid further strain on the existing power grid, it would make sense to charge the electric minibus taxis “through a grid consisting of renewable energies.”

According to the research team member Johan Giliomee, minibus taxis could be supplied via the installation of solar panels and battery energy storage systems at taxi ranks. Hydrogen could also be used as an alternative electricity source or for interim energy storage.

“The vast majority of taxis are stationary between the early morning and afternoon peaks, making it an ideal opportunity for charging from solar panels,” Giliomee said.

“This also means a single charge would only need to supply sufficient energy for half the day, significantly reducing the required battery capacity as opposed to being scaled to support a full day’s operations. Further ideal charging opportunities are seen overnight when the national electricity demand is at its lowest.”

Booysen suggested shifting the focus of the national discussion on electric vehicles to encompass a system-based approach to electric mobility that includes decentralized electricity provision in light of the nation’s energy woes, writes BusinessTech.

Ambitious plans

Stellenbosch University is also doing a retrofit project with Golden Arrow Bus Services, which has 1,100 diesel buses that could be retrofitted.

According to Lacock, Golden Arrow needs to buy new buses every year to keep the fleet up to date, and the company is losing money by writing the old ones off.  Based on the Golden Arrow EV pilot programme, the researchers at SU around ZAR657,000 (about $35,000) per bus per year could be saved on operational costs if electric.

Booysen said the next step would be developing the country’s own motors and vehicle controlling units, adding that a big remaining challenge for South Africa is that it does not yet make batteries. “For me, this is the big prize,” he noted.  

Now that the EV taxi is up and running, it will be taken back to Stellenbosch to do an efficiency analysis and verify the laboratory simulations, to help determine where the charging stations need to be, where solar power is needed and what the load will be on the grid based on the efficiency.

“That’s the first thing because even though we do believe in electric mobility changeover, we know that the grid can’t handle it,” Lacock told Daily Maverick.

“Yet we can’t stop, because somewhere in the future – in 2035 [when the EU and UK, South Africa’s biggest exporters, have put a stop on ICEV sales] we need to be electric.”