The development of carbon neutrality pathways requires multiple approaches so that emissions in all sectors can be decarbonised effectively. This chapter investigates the maximum contribution of all clean technologies, renewables and fuels to meet carbon neutrality. It presents a variety of ERIA studies, particularly the study on “Decarbonisation of Energy Systems: Optimum Technology Selection Model Analysis up to 2060”, which uses data from a linear programming model to minimise the total cost of the energy system when various constraints such as CO2 emissions and power supply-demand balance are given, in order to check the maximum contribution of all available clean technologies and renewables in the ASEAN decarbonisation scenario. The key issues and findings provide policymakers with a recommended strategy to scale up these clean technologies and renewables in an affordable manner, necessary given all the barriers and costs associated with ASEAN’s projected deep decarbonisation. This chapter also examines the policy implications of ASEAN’s decarbonisation and discusses the need for each country to formulate strategies which comply with its own unique socio-economic conditions.