Determining the optimal energy use mix in a low-income household

Energy use is crucial to our way of living and is fundamental for sustainable development, but often negatively affects human health and the environment. Around 60 percent of low-income households on the South African Highveld rely on solid fuels to meet their energy needs (cooking, water heating and space heating, especially in winter), despite being electrified. The aim of this research is to optimise energy use mix in a typical low-income household on the Highveld for least cost, lowest carbon dioxide (CO₂) emissions and lowest particulate matter (with aerodynamic diameter less than 10 μm - PM₁₀) emissions. The study employs secondary data from Eskom's air quality offsets pilot project in KwaZamokuhle and other studies on energy use patterns. The energy requirements and constraints for an insulated, formal house are expressed as linear programming problems. The solutions reveal that using coal for cooking, space and water heating, and electricity for lighting and appliances, is the least cost option. However, for lowest CO₂ and PM₁₀ emissions, liquid petroleum gas (LPG) is most suitable for cooking, space heating and water heating, and electricity is preferred for lighting and appliances. These findings suggest that policies and initiatives that encourage LPG and electricity use should improve air quality in low-income communities and aid in climate change mitigation, but will not be sustainable unless the LPG or electricity is affordable for households.