The need for a shift to more sustainable and eco-friendly sources of energy has increased sharply in the last three decades. While this change is highly welcomed, there is a need to ensure that the transition is sustainable from an economic and product supply point of view. The notion that fossil fuels are only required for energy generation does not do justice to industries that are reliant on the numerous products obtained from them. 

Asphalt, activated carbon and platform chemicals are just a few of the many products obtained from fossil-based fuels. Any shift towards resources that are only able to produce electricity will not lead to a just replacement of fossil-derived products.

Transportation plays a crucial role in the development of countries, and the efficient movement of goods and services is a reflection of the growth and development of any nation.

The transportation sector remains unique in its energy utilisation, considering that it uses liquid fuels in most cases. These liquid fuels are rich in hydrocarbons which are used in different internal combustion engines and the use of wind and solar energy sources has limited applications in the sector. Consequently, focussing on them will only tend to address the concerns of power generation at the expense of other key industries.

Biomass derivatives are rich in carbon and hydrogen that can be easily transformed to a number of fuels and petrochemicals like those obtainable from fossil fuels. In addition, unlike fossil fuels, the contribution of biomass derivatives to the net emission of greenhouse gases is minimal, since their emissions easily find ways of being recycled naturally via photosynthesis.

The thought of having zero CO2 emissions is a utopia that is still scientifically debatable and may not be actualised in the near future. The practicality of this aspiration is rendered more complex by the fact that internal combustion engines remain unrivalled in terms of performance. These engines, which are the touchstone of the transportation industry, have been designed to work on hydrocarbon fuels. It is therefore necessary that a holistic approach, underpinned by science, is adopted as we transition from fossils to renewables.

Logistical complications

While South Africa has identified the need to find realistic and sustainable solutions to challenges facing its electricity sector, it is worth noting that relying on solar and wind as potential replacements for coal utilisation is an idea that comes with numerous challenges. 

South Africa’s stunning geography is as diverse as its potential resources. This diversity reflects the amount of sun and wind that can be harnessed in the country. The variability of these resources makes it an uphill task to ensure supply as and when needed.

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While wind and solar could be harnessed in remote areas, the need to transmit electricity to industrial areas that are usually far from the generation sources poses another challenge in the implementation of wind as a source of energy in South Africa. A typical example is the potential of wind farms in the Eastern Cape and the need to transmit the generated electricity to industrial hubs like Gauteng.

Furthermore, the associated costs of generating electricity from solar and wind are still high and may not be readily affordable without several government interventions.

Bio-derived resources on the other hand will easily leverage existing structures to produce fuels and other petrochemicals. The existing refineries in various provinces of South Africa can be readily reconfigured to accommodate various feedstocks that can undergo thermochemical conversion to produce numerous products.

Agricultural input

The large-scale agricultural activities in KwaZulu-Natal and Limpopo could serve as potential feedstock supply for utilisation in biorefineries. At this stage, it is worth clarifying the misconception that the utilisation of bioresources could lead to a decline in food supply. A shift towards bioresources will actually boost the utilisation of fertile and abandoned land to produce food alongside energy crops that have the potential of boosting farming and helping local farmers. This change will lead to economic growth and development in general. 

There is no better solution to the replacement of fossil-derived fuels than the use of resources that will ensure a just transition with minimal impact on the livelihoods of those dependent on fossil fuel-related activities.

Having noted that there remains a void that has not been filled by solar and wind energies as replacement for fossil fuels, there is a need to strategically work towards ensuring that the often-disregarded contribution of biomass-derived resources gets the necessary recognition.

Various feedstocks, including organic waste, as well as agricultural and industrial byproducts, have the potential to serve as feedstock for the production of bioproducts, including fuels and petrochemicals.  

Animal husbandry-related activities could serve as potential sources of biomethane as well as compost for enhancing soil fertility. Biomethane can be centrally generated and distributed for domestic use.

While this practice has been found to be very effective in many Asian countries, South Africa has yet to leverage the available resources to produce biomethane that could be used domestically and in some industries. A successful implementation of biomethane production and distribution networks will surely be of benefit to many communities. 

Case for biogas

Biogas is not the only fuel that can be generated from biomass. Technically, all products obtainable from fossil fuels can also be produced from biomass. The challenge with biomass utilisation has to do with its heterogeneous nature. However, this should be seen as an added advantage in the production of biomass-derived products.

Just like the complexity of crude oil allows for the production of a wide spectrum of products, the complex nature of biomass and organic wastes allows for the production of various products via thermochemical conversion processes.

The chemical processing industry in South Africa enjoys the historic advantage of infrastructure that has the potential of transforming coal into synthesis gas, often referred to as syngas. In simple terms, syngas is a mixture of hydrogen and carbon monoxide and has the capacity to act as both fuel and raw material for petrochemicals, hence serving as a starting material for many products.

Numerous processes require secondary pre-treatment units that are applicable to upgrading biomass-derived oils (bio-oils) to value-added products like gasoline, diesel, and aviation fuels. From a technical point of view, existing refinery infrastructure can be used for the conversion of biomass derivatives to value-added products with little or no modification. 

The catalytic conversion of biomass to liquid and gaseous products has proven to be a source of transport range hydrocarbons, as well as gaseous products that are rich in syngas. These products can be fed to existing plants for the production of chemicals and fuels similar to those obtainable from fossil-based fuels.

As South Africa focuses on the just energy transition, it is worth noting the significant role of biomass as the potential substitute for fossil resources. Biomass is available across the country, which makes it a readily available and cheap raw material for biofuels and bioproducts.

Consequently, policies need to be implemented towards the efficient utilisation of bioresources. There is also a need to create awareness of the role of this priceless resource in the just energy transition. DM

Yusuf Isa is an Associate Professor in the School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand.

Thokozani Majozi is the Executive Dean, Faculty of Engineering and the Built Environment and Full Professor in the School of Chemical and Metallurgical Engineering, University of the Witwatersrand.