Techno-economic assessment of bio-compressed natural gas as a transport fuel for South African Provinces

Abstract

South Africa's transport sector is a major contributor to carbon emissions due to its reliance on liquid fossil fuels such as diesel and petrol. In a bid to decarbonize the transport sector, South African government is committed to developing its green economy through the use of clean and renewable energy sources. Biogas, as a renewable energy source, can be derived from food waste (FW); upgraded to bio-compressed natural gas (bio-CNG) and applied as a vehicle fuel. This study assesses the economic feasibility of upgrading biogas to bio-CNG as a transportation fuel in South African provinces. The FW generation was determined using a mixture of population and income models while the biogas generation is modelled using modified Bushwell's equation. The economic analysis was premised on four economic metrics such as net present value (NPV), payback period (PBP), internal rate of return (IRR), and levelized cost of bio-CNG (LCO-bio-CNG). Some important findings indicate that an average of 6.6717 million tons/year of FW is generated in South African provinces producing 11.7111 million Nm3 of bio-CNG which is capable of filling about 1.2 million 10 m3 compressed gas cylinders. Economically, the project is profitable with positive NPV in all provinces, less than 2 years PBP, minimal LCO-bio-CNG (0.0551–0.0807 USD/m3) as well as remarkable IRR (31.15–36.08 %). Sensitivity analysis was also conducted to determine the influence of some critical parameters on the general performance of the project. This study provides valuable information for optimal investment in bio-CNG for public transportation.