Indonesia's LTS-LCCR, 2nd NDC and RUPTL imply deep changes in the power sector, yet coal still dominates generation and current policies appear insufficient. This study applies the OSeMOSYS model to analyse five scenarios for 2015–2050. For each pathway we quantify total discounted system costs, emissions and marginal abatement costs, and test robustness through ±20% renewable capital cost and natural gas price sensitivities and discount rate variations. The results show that Indonesia's existing carbon tax of USD 1.8/tCO 2 leaves the generation mix and emissions almost unchanged relative to business as usual, while a high carbon price delivers low cost abatement mainly through coal to gas switching but does not achieve deep decarbonisation and is highly exposed to gas price volatility. Renewable pathways achieve the largest emissions reductions and approach a near zero carbon power system, with moderate MACs but higher upfront system costs and strong sensitivity to capital costs and financing conditions. Overall, the findings indicate that Indonesia's climate goals cannot be met with the current low carbon tax or gas based abatement alone. They require rapid renewable deployment coupled with de-risked finance, stronger regulatory coordination and targeted use of carbon pricing revenues to support grids and storage. These quantitative results are conditional on today's codified policy frameworks and should be interpreted as indicative transition pathways rather than precise forecasts. • Five power sector pathways for Indonesia modelled with OSeMOSYS. • Current USD1.8/tCO 2 carbon tax leaves emissions almost unchanged from BAU. • USD100/tCO 2 carbon price delivers low cost abatement via coal-gas switching. • Renewable pathways approach net-zero but require high upfront investment. • Results stress need for de-risked finance and stronger policy to scale renewables.
Afriani et al. (2026) studied this question.