Techno-economic assessment of coal-to-liquid derived carbon dioxide capture and utilisation for sustainable methanol production in Botswana

Without mitigation, a Coal-to-Liquids (CTL) plant in Botswana, with an annual capacity of 1.5 million tonnes of liquid fuels, would emit about 4.5 million tonnes of Carbon Dioxide ( CO 2 ) to the environment. This would increase the national greenhouse gas inventory. Hence, the current study undertakes a Techno-Economic Assessment (TEA) of capturing CTL byproduct CO 2 and converting it into synthetic methanol ( CH 3 OH ). A Matrix Laboratory (MATLAB) based model was developed for CTL carbon capture and utilisation (CCU) through CO 2 to CH 3 OH . The MATLAB model confirmed that methanol output, hydrogen, and electricity consumptions increased with increasing capture fraction. Hydrogen and electricity costs dominated the variable Operating Expenditure (OPEX) and identified as the main economic barriers. The annual TEA showed that at capture fractions between 60% and 95%, 2.7–4.3 million tonnes of CO 2 per annum can be diverted through CCU, reducing CTL emissions to a minimum of about 0.3 million tonnes per annum. A sensitivity analysis confirmed that CO 2 credits significantly contribute to revenues. A near breakeven was only achieved at green hydrogen price of 0.75 USD/kg, electricity price of 75 USD/MWh, CO 2 credit of 350 USD/t and methanol at 400 USD per tonne.