**5. Energy Landscape in the Mekong Subregion**

The data sources presented in Figures 1–5 are provided by country experts in the Mekong subregion who are the members of the ASEAN and East Asia Energy Outlook managed by ERIA. One of the co-authors of this paper is also the coeditor of the East Asia Energy Outlook. The presented numbers are also derived from using the Longrange Energy Alternatives Planning (LEAP) system software, an accounting system used to develop projections of energy balance tables based on final energy consumption and energy input/output in the transformation sector. LEAP is also an energy modeling software capable of conducting a variety of analyses of energy systems including Demand Analysis, Transformation Analysis, Resource Analysis, and Environmental Analysis. The data structures in a LEAP are organized using a hierarchical tree. The types of data entered at each branch depend on the type of branch, and its position in the tree (for example whether it is a Demand or Transformation branch). At the core of LEAP is the concept of scenario analysis. Scenarios are self-consistent storylines of how a future energy system might evolve over time in a particular demographic and socioeconomic setting and under a particular set of policy conditions. Using LEAP, we can build scenarios and then compare them to assess their energy requirements, social costs and benefits, and environmental impacts. All scenarios start from a common base year. We can use scenarios to ask an unlimited number of 'what if' questions, such as: what if more efficient appliances are introduced, what if different electric generation capacity expansion plans are pursued, what if indigenous reserves of oil and gas are discovered, what if renewable energy technologies are introduced, and so on. From here, the results presented in Figures 1–5 are the authors' calculations based on the country data provided by the regular members of ERIA's energy outlook and energy-saving potential panel of experts.

**Figure 1.** TPES by energy source, BAU (in blue) vs. APS (in red). APS = alternative policy scenario, BAU = business as usual, TPES = total primary energy supply. Source: authors' calculations.

**Figure 2.** TFEC by sector, BAU (in blue) vs. APS (in red). APS = alternative policy scenario, BAU = business as usual, TFEC = total final energy consumption. Source: authors' calculations.

**Figure 3.** Total power generation (TFEC) by energy source, BAU (in blue) vs. APS (in red). APS = alternative policy scenario, BAU = business as usual, TFEC = total final energy consumption. Source: authors' calculations.

**Figure 4.** Investment in power generation by energy source, BAU vs. APS. APS = alternative policy scenario, BAU = business as usual, PV = photovoltaic. Source: authors' calculations.

**Figure 5.** CO2 emissions in the Mekong Subregion, BAU (in blue) vs. APS (in red). APS = alternative policy scenario, BAU = business as usual, CO2 = carbon dioxide, Mt-C = million tonnes of carbon equivalent. Source: authors' calculations.
