**6. Conclusions and Policy Implications**

The results of various scenarios have shown that ASEAN's current and future energy mix relies greatly on fossil fuels. The current share of fossil fuels is almost 80% in the primary energy supply and its future share is projected to be 87% under the BAU scenario and 78% under the APS. ASEAN's emissions will remain very high in all APS scenarios. To limit the temperature rise to 2◦ Celsius, emissions will need to fall to half by 2030 and reach net zero emissions by 2050 from 2010 levels. Thus, the clean use of fossil fuels through clean technologies and CCUS will be the only technological options to decarbonize emissions from fossil fuel use. In the energy transition, natural gas should be promoted as a transitional fuel in ASEAN, given the abundant supply from Australia. Renewables, energy efficiency, and green hydrogen (Green hydrogen refers to the hydrogen production from renewable electricity.) should be accelerated—along with the adoption of clean ecotechnologies—in the medium to long term in ASEAN's future energy system. Policies to manage ASEAN's energy transition need to be weighed against potentially higher energy costs, affordability, and energy security risks. Oil is the dominant energy source in the transport sector, while natural gas and coal are the dominant energy sources for power generation in ASEAN. The higher share of natural gas in ASEAN's power mix is a step in the right direction in promoting natural gas use in the energy transition towards a cleaner energy system.

In many ASEAN countries, coal use in power generation has been locked into the foreseeable future energy mix, as current and future coal-fired power generation generally involves 20- to 35-year power purchasing agreements with state-owned utilities to provide electricity. Thus, ignoring coal use in ASEAN means ignoring the reality and emissions of coal use. Considering the clean use of coal as part of ASEAN's energy transition is crucial to address the priorities of energy affordability and climate change. The deployment of CCT is urgent in the ASEAN region. Although ASEAN's energy targets have been set to include more renewables, ASEAN faces challenges in implementing such targets because renewables remain expensive in terms of the system integration cost to achieve high penetration in the grid system. Smart grids using the internet of things will provide a new green investment infrastructure which allows more penetration of renewables, but significant investment is required such as hard grids, internet of things technologies and applications, data management, and human resources.

A cleaner energy system in ASEAN relies on today's actions, policies, and investments to accelerate a higher share of renewables, the adoption of clean technologies and clean use of fossil fuels, and investment in climate-resilient energy quality infrastructure. The need for variable renewable investment in the power mix is estimated to be \$118 billion in the APSs. Finally, willingness to pay is crucial if ASEAN is to leapfrog from its current energy system towards more efficient and clean technologies and a higher share of renewables in the energy mix.

Below are the key policy implications from the study:


**Author Contributions:** Conceptualization, H.P., F.K. and J.A.; Data curation, H.P.; Formal analysis, H.P.; Investigation, H.P.; Methodology, H.P.; Software, H.P.; Supervision, F.K. and J.A.; Writing original draft, H.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.







APS alternative policy scenario, APS\_EI alternative policy scenario with energy intensity targets, APS\_EmT alternative policy scenario with emission reduction targets, APS\_REalternative policy scenario with renewable targets, BAU = business as usual, Mtoe = million tonnes of oil equivalent. Source: Authors' calculations.

alternative policy scenario with renewable targets, BAU = business as usual, Mtoe = million tonnes of oil equivalent. Source: Author's calculations.


APS = alternative policy scenario, APS\_EI = alternative policy scenario with energy intensity targets, APS\_EmT = alternative policy scenario with emission reduction targets, APS\_RE = alternative policy scenario with renewable targets, BAU = business as usual, TWh= terawatt-hour. Source: Authors' calculations.

**Table A4.**

Estimates of Final Energy

Consumption

 and Percentage Changes from BAU to APSs, 2050 (Mtoe).

Hydro

Geothermal

Others

**Total**

 183 267 276

 23 37 37

 14 91 169

 **1041 1768 1622**

 4

 1

 86 *−***8**

 **1892**

 193

 39

 397

 49

 7

 113

 **7 1607**

 86

 35

 267

 0 −5

−5

*−***9**

 **1416**

 201

 38

 278

 4

 2

 122 *−***20**




alternative policy scenario with renewable targets, BAU = business as usual, Mt-C = million tonnes of carbon equivalent. Source: Authors' calculations.

alternative policy scenario with renewable targets, BAU = business as usual, TWh =

terawatt-hour.

 Source: Authors' calculations.


**Table A8.** Estimates of CO2 Emissions and Percentage Changes from BAU to APSs, 2050 (Mt-C).

APS = alternative policy scenario, APS\_EI = alternative policy scenario with energy intensity targets, APS\_EmT = alternative policy scenario with emission reduction targets, APS\_REalternative policy scenario with renewable targets, BAU = business as usual, Mt-C = million tonnes of carbon equivalent. Source: Authors' calculations.
