<p>Municipal solid waste (MSW) is often used as Refused Derived Fuel (RDF) for the waste-to-energy technology option. Generating electricity from MSW is always claimed to be less economically competitive as compared to conventional fossil fuels. This techno-economic (TEA) study investigated the potential of coal substitution in the largest coal power plant in Malaysia, Stesen Janakuasa Sultan Azlan Shah (SJSAS), by hydrothermally treating MSW from Teluk Mengkudu landfill. The results indicate that for the Hydrothermal Treatment Technology (HTT) design treatment capacity of 300 tonnes/day (t/d), the total investment cost for three (3) HTT reactors at 20 m³ capacity values at USD 12.4 million. Also, 30,499 tonnes of hydrochar are available to supply to the coal plant annually, which accounts for a 0.25% thermal substitution rate with a net CO₂ avoidance of 38,741 tonnes annually. Approximately 0.02% and 0.01% of the cumulative CO₂ avoidance renewable energy target in 2030 and 2050, respectively, can be achieved from this study. For a 20-year project term and an 8% discount factor, the Net Present Value (NPV), Internal Rate of Return (IRR), and payback period (PP) are estimated at USD 3.76 million, 11.9%, and 7.5&#xa0;years, respectively. Sensitivity analysis revealed that hydrochar selling price and discount factors greatly influence the profitability of the project. The importance of the research is highlighted by the fact that the HTT from MSW as a coal alternative is attractive both economically and environmentally, as it can yield high profits from the value-added products towards sustainable landfill upgrading and waste valorisation in Malaysia.</p> Graphical abstract <p></p>