**7. Conclusions and Policy Implications**

The Mekong Subregion's fast connectivity—including rail, road, port, aviation, and energy infrastructure—has integrated the region further in terms of compressing time and space for the movement of goods and services. However, the wider ASEAN region faces challenges in guiding investments for long-term sustainability, especially on quality infrastructure. In the region, key players channel their investments through regional and subregional initiatives and platforms such as China's BRI and LMC, the US BDN, the FOIP, the MRC, and Mekong–Japan Cooperation. Although there is a clear need for resilience and quality infrastructure in the Mekong Subregion, policy measures and actions undertaken in each country towards high-quality infrastructure vary, reflecting the differences in socioeconomic, political, and geographical contexts. Thus, this makes it difficult for the region to promote sustainable growth and a low-carbon economy, energy access and affordability, and resilient and sustainable quality infrastructure.

As the Mekong Subregion continues to rely on fossil fuels, its energy transition will need to consider cleaner use through clean technology investment such as HELE technologies and other high-quality energy infrastructure. Currently, investment in renewable energy and clean technologies is unstable and high in cost. These challenges need to be addressed through political commitment to ensure that an energy technology development and deployment support framework can scale up the share of renewables and clean fuels. Without redesigning energy policy towards high-quality energy infrastructure, it is very likely that the increasing use of coal will lead to the widespread construction of CPPs, which, without the employment of the best available HELE technologies, will result in increased GHG [1,77].

The investment opportunities for energy-related infrastructure are huge. This study estimates that around USD 190 billion–220 billion will be required from 2017 to 2050 for power generation alone. However, this estimate does not include the transmission and distribution network, LNG terminals, and refineries. The challenge will be to ensure quality infrastructure to promote sustainability in the region. Energy sustainability in the Mekong Subregion requires an increase in the share of renewables in the energy mix. Currently, it is dominated by coal, gas, and hydropower. Although intermittent renewables (solar and wind) comprise the most abundant energy resources in the region, they have so far taken a minimal share of the power mix.

As this study shows what countries in the Mekong Subregion will need, as development accelerates and climate change intensifies, is an environmentally friendly, logistically feasible, and economically responsible alternative energy source and infrastructure. Derived from this study, the following key policy implications are provided with this consideration in mind.

First, the region will need to promote quality infrastructure investment. Given the region's vulnerability to climate change, resilient and high-quality infrastructure will play a key role in the region's long-term sustainability. Thus, regional and subregional platforms and initiatives such as the BRI, quality infrastructure by Japan, the BDN, and other subregional initiatives will need to promote high-quality infrastructure investment. For instance, the region should and will need to discuss the quality and standards that can guide investment to meet the need for high-quality infrastructure. Willingness to pay could be a barrier because of the high cost of quality infrastructure. Thus, a mechanism to reduce costs through innovative financing will be important for the successful deployment of high standards in the region.

Second, the current climate narrative and policy approach of banning coal use will need to be reviewed to assist emerging Asia to afford HELE technologies. This is primarily because there are less available alternative energy options in the medium term to meet energy demand. Treating HELE technologies as a technological solution in the energy transition will be a win–win solution for a climate-friendly world as Asia faces energy accessibility and affordability. Emerging Southeast Asia will rely on whatever HELE technologies are available in the market at affordable prices. The up-front costs of such ultrasupercritical technology or advanced ultrasupercritical technology are higher than supercritical and subcritical technologies. Thus, it is necessary to lower the up-front costs through policies such as attractive financial/loan schemes or a strong political institution to deliver public financing for HELE technologies in the region.

Third, there is a need for public consultation on and local participation in the potential impacts of any selected power plant infrastructure and technologies. However, for the Mekong Subregion, the government institutions have not emphasized such local participation strongly enough, just yet. Thus, an active organization or mechanism is needed to disseminate information on the potential harm resulting from less efficient CPPs.

Fourth, the region will see a rise in LNG imports to meet demand. Thus, the region's leaders will need to consider energy policy to increase the use of LNG in the future as a bridging fuel towards a clean energy future. Redesigning policy to promote LNG use will, to some extent, reduce coal use in the power mix. The countries in the Mekong Subregion

should investigate the LNG infrastructure gap to develop policy to promote investment. This includes LNG terminals, pipelines, regasification plants, transportation, and storage.

Fifth, the region will need to prepare for a sharp increase in renewable energy from wind, solar, and biomass in the energy supply mix; and at the same time, promote the use of clean fuels and clean technologies. It will also need to look wider in terms of power grid connectivity. In this case, investment in 'hard' quality infrastructure will need to be connected to ASEAN.

Finally, the Mekong Subregion should boldly increase the portion of funding in the economic recovery package on green energy investment, as it will promote jobs, environmental protection, and social benefits for long-term sustainability. Governments and financial institutions may need to promote the financing of green projects through green bonds or other financial instruments. Of course, the region will also need to work on carbon credits in the future, as this will promote renewable and clean technology development.

**Author Contributions:** Conceptualization, H.P. and S.M.; methodology, H.P.; software, H.P.; validation, H.P., S.M., and H.P.A.; formal analysis, H.P.A. and S.M.; investigation, H.P.A.; resources, H.P.A.; data curation, H.P.A.; writing—original draft preparation, H.P.A.; writing—review and editing, S.M., H.P.A., and H.P.A.; visualization, H.P.A.; supervision, H.P.A.; project administration, H.P.A.; funding acquisition, H.P.A. 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.

## **References**

