Heavy fuel oil: a sustainable solution in South Africa’s energy transition
iSolvents Chemicals
For many years the main source of energy in South Africa has been natural energy in the form of coal. But with the increasing demand for energy, South Africa must transition to mixed energy sources. One of the largest generators of energy for us now is crude oil.
Crude oil is a complex mixture of energy rich compounds. These compounds vary in size and are separated according to their size when the crude oil is heated and distilled. Once distilled the oil is fractioned into a range from lighter oils to heavier oils: petrol, naphtha, paraffin, diesel, fuel oil, lubricating oil, and heavy fuel oil.
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Because of this, heavy fuel oil cannot be burnt entirely as a fuel. The larger carbon molecules trapped between impurities do not reach high enough temperatures to be consumed. This incomplete combustion must take place in large engines as well to prevent the release of toxic compounds.
Heavy fuel oil is characterized by its high density and high viscosity. It only flows if it is heated to 40 degrees Celsius, sometimes 60 degrees Celsius. This is because of the most significant impurity in heavy fuel oil. It is called asphalt.
Asphalt occurs naturally in sand and clay. It is sticky and black, and often considered a semi-solid because it acts as a solid at temperatures below 40 degrees Celsius but begins to flow like a liquid above that temperature. Asphalt is nearly impossible to break down or filter out of heavy fuel oil. But instead of removing asphalt, another strategy is considered when making heavy fuel oil.
Manufacturing Heavy Fuel Oil
Because heavy fuel oil is a mixture of irredeemable compounds and oils, it is thought to be made up of two components: undesirable impurities like asphalt, and heavy oils that can be used to generate energy through combustion. A considerable strategy to make heavy fuel oil is to recycle spent oils by adding them to asphalt mixtures. Thinning out the asphalt and making usable heavy fuel oil. This releases some of the heavier oils already present in the asphalt mixture, making these heavier oils accessible for combustion.
The process of recycling spent oil to loosen heavy asphalt is called asphalt rejuvenation. Asphalt rejuvenation has attracted more attention in the last year because it reduces carbon emissions during combustion, saves resources, and protects the environment (Shiao et al., 2022). This is because spent oil such as motor engine oil – that otherwise goes into wasteland or the ocean – is now used to manufacture heavy fuel oil instead.
There are three environmental benefits to rejuvenating asphalt, and each of them has an immediate effect when heavy fuel oil is manufactured from spent oils.
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In the past it was thought that the burning of heavy fuel oil has negative environmental effects. But considering the three points in table 1, manufacturing it from spent oils has greater positive impacts on the environment. Undertaking the production and use of heavy fuel oil must be done, especially in developing countries like South Africa. |
A research group of the Department of Industrial and Production Engineering at the University of Bangladesh studied the developing region of Southern Asia (like that of South Africa).They found that the manufacture of heavy fuel oil through asphalt rejuvenation has a direct influence on energy availability. And that this goes beyond the needs of the industrial sector. Senior researcher Bari Mainul says that developing regions must depend on the energy generated by the burning of heavy fuel oil to meet electricity demands. This affords industries the opportunity to grow. It also increases the average quality of life for every citizen as more energy is made available for domestic use (Mainul et al., 2022). If we want to make positive changes for the energy situation in South Africa, or consciously take care of our environment, both can be done by manufacturing heavy fuel oil.
Manufacturing heavy fuel oil by reusing spent oil also adds to the welfare of the economy. Asphalt rejuvenation stimulates the economy in three ways that are meaningful to South Africa. Firstly, by saving on the costs of purchasing crude oil. Secondly, it increases the revenue of oil refinning facilities. And thirdly, it creates opportunity for new jobs since these projects require skilled labour. Recycling asphalt is also done in the pavement and construction industry (Amirul et al., 2020), which has been a good area for job creation in South Africa.
Whether we want to generate more energy or stimulate our economy in a novel way – our focus is to create a sustainable solution that repurposes waste as a resource.
References
Amirul I.R., Alireza S., Ali Z., Kamil E.K., Brajendra K., Sharma F., Elham H.F. (2020): Do all rejuvenators improve asphalt performance?, Road Materials and Pavement Design.
Mainul B.A.B.M., Siraj M.D.T., Sanjoy K.P., Sharafuddin A. K. (2022): A hybrid multi-criteria decision-making approach for analysing operational hazards in Heavy Fuel Oil-based power plants, Decision Analytics Journal, Volume 3, 100069, ISSN 2772-6622.
Shiao Y., Qiao D., Xueqin C., Changjun Z., Shi D., Xingyu G. (2022): Application of waste oil in asphalt rejuvenation and modification: A comprehensive review. Construction and Building Materials, Volume 340, 127784, ISSN 0950-0618.