Talk of alternative energy technology and fuels has increased in frequency and prominence among stakeholders in the transport industry, with both the public and private sectors having made commitments to decarbonise transport.

For public entities responsible for ensuring viable public transport, the question of transitioning to alternative fuels was now a pertinent one, consultancy Zutari senior transport economist Marco Steenkamp said during a presentation at the Southern African Transport Conference on July 10.

He explained that transport authorities were faced with a developmental dilemma of investing in infrastructure and public transport operations in a rapidly changing environment.

These authorities needed to plan for future contexts, while balancing the needs of the present, Steenkamp added.

To support effective decision-making, policymakers and public transport authorities need to consider the total cost of ownership (TCO), total cost impact in terms of cumulative cash flow on budgets and emission reduction measures of its public transport operations – all while remaining cognisant of global trends, competing domestic priorities and budget constraints.

Steenkamp cited research that found that electric buses only broke even with diesel-driven buses from a TCO point of view after 15 years, with eight years being the best-case scenario if more renewable energy was developed and transmitted through the grid.

Globally, policy imperatives exist related to achieving net zero and reducing greenhouse-gas emissions, according to new legislation, particularly in Europe and China, supporting the Paris Agreement.

China, Japan and the US are offering subsidies and tax incentives related to the adoption of electric vehicles.

In this regard, South Africa supports green initiatives through a number of funding opportunities, including through the Green Fund, Green Finance Platform, Development Bank of South Africa’s green bond framework, private sector participation and National Treasury.

However, various factors need to be taken into consideration before switching a bus fleet from being diesel-driven to electricity-driven, including depot infrastructure, electrical support infrastructure, charging equipment, the number of bus routes, the length of bus routes and the size and mix of the bus fleet in any given area.

Capital expenditure for both diesel and electric buses relates to the size of the bus fleet, battery replacement, chassis refurbishment and electrical infrastructure, including power distribution, network connection and charging equipment.

Operational expenditure relates to insurance and licence fees, electricity or fuel costs, lubricants, maintenance and tyre replacement.

These factors all inform the TCO, in which electric buses would only break even in terms of costs with diesel-driven derivatives after 15 years.

Additionally, Steenkamp said the difference in emissions would not be as significant as expected from an electric bus fleet, given that the baseload of the country largely comprises coal-fired power generation.

A mixed fleet relative to a full diesel fleet provides for marginal cost savings in terms of the TCO at about 2% over the lifespan of the buses.

The difference in TCO of a full diesel fleet relative to a full electric fleet is far greater at about 14%.

Steenkamp pointed out that there was a notable decrease in the operational expenditure of a full electric fleet after a few years, compared with that of a mixed or diesel fleet; however, the high capital cost of an electric fleet was what took time to offset.

While electric buses may be cheaper to operate in the longer term and require less maintenance, insurance and licence fees may end up being higher.

The total CO₂ emissions for the full diesel fleet scenario is about 0.014% of the total transport contribution to carbon emissions in South Africa.

Steenkamp found the replacement of 12 m and 18 m diesel buses with electric buses would ensure a 0.22% decrease in CO₂ emissions in South Africa.

Over the 18-year operational period, about 150 000 t of carbon emissions would be avoided, which, if adopted across major cities in South Africa, would have a cumulative reduction of about 2.3-million tonnes of CO₂ – which remains marginal.

Steenkamp therefore concluded that while operating an electric bus fleet would have lower operating cost over a 19-year analysis period and contribute to 14% lower CO₂ emissions than an equivalent diesel fleet, the total capital cost to electrify bus fleets would still be 118% greater relative to a diesel fleet.

“Emission reduction through the adoption of a full electric business fleet remains marginal and costs only reach breakeven point after 15 years – four years away from the buses’ end-of-life,” Steenkamp said.