Socioeconomic feasibility study of an integrated waste tyre pyrolysis and electricity generation system in the Gauteng region of South Africa

Abstract

This study assesses the socioeconomic feasibility of an integrated waste tyre pyrolysis and electricity generation system in the Gauteng region of South Africa. The primary aim of the research is to address two of South Africa’s challenges, waste tyre management and electricity generation shortages, by integrating waste tyre pyrolysis with a gas turbine. This research is in direct response to the call for further research into the applicability of pyrolysis from the South African government. Gauteng is a highly populated and economically significant province, which provides a crucial case study for this system due to its substantial waste tyre stockpiles, built-up infrastructure, dense population, and high electricity demand.

The designed system involves the pyrolysis of waste tyres to produce char and oils, which are then used to generate electricity through an external gas turbine. This integrated approach highlights the applicability of using pyrolysis outputs for electricity generation, bypassing the need for uncertain secondary markets for pyrolysis products. The system design relies on the availability of waste tyres, regulatory considerations, and market demands for electricity, sizing the system first for the desired electricity generation capacity and fitting the pyrolysis size to meet the demands for electricity generation.

The economic analysis shows that the combined system is a highly feasible solution, with a Net Present Value (NPV) of approximately R4.85 billion and a payback time of 5.4 years, building a solid investment case. The Levelised Cost of Electricity (LCOE) is calculated at 0.12 R/kWh, making the system more cost-effective than current electricity generation methods in South Africa under the national generation company. The economic model’s outlook and results are supported by sensitivity analyses, which indicate the system remains feasible under changing waste tyre and electricity prices, even without government subsidies, a critical condition to eligibility for the support schemes.

The Social Cost-Benefit Analysis (SCBA) reveals a range of significant societal benefits that the integrated system provides. These include job creation, improved power quality, and increased national economic output through reduced load shedding. The system’s Social Net Present Value (SNPV) is strongly positive at R8.56 billion, with significant social benefits across various different sectors. Further, the results highlight the benefits of pyrolysis for waste tyre management over the direct use of tyres in coal power plants, making a clear case to the government regarding the processing method to pursue. Significantly, these benefits outweigh the additional carbon emissions from the increased electricity generation capacity and the increased tax burden of the subsidies to the processing system. Not all of the societal benefits are evident in the SCBA; the system also plays a role in public health improvements and a reduction in road accidents by addressing the waste tyre stockpile issue. These benefits further highlight the potentially significant gains for society following implementation.

The study concludes that the proposed system is a socio-economically feasible solution for Gauteng’s waste tyre and electricity challenges. And a potential driving force for South Africa’s energy landscape transition, paving the way for renewable energy systems to connect to the grid en masse through the added grid stability. Its positive economic indicators and net societal benefits make it a promising candidate for addressing South Africa’s energy transition and waste tyre management goals, meeting all of the government’s objectives of the Industry Waste Management Plan and fitting into the Renewable Energy Independent Power Producer Role. The study paves the way for future research to focus on environmental impacts, changing system assumptions and long-term electricity grid impacts.