Power Islands. The geography of electricity diffusion in Indonesia, 1975–2018

Using the case of Indonesia, we provide novel evidence that the spatial diffusion of electricity technology in the global South is a lengthy and non-linear process that is influenced by local geographic, economic and demographic conditions. We do so on the basis of newly developed consistent time series data on installed electricity generation capacity and household electrification ratios from previously unpublished energy statistics at the (sub-)regional level in Indonesia, for the period 1975 to 2018. We identify spatial interactions in historical electricity adoption rates that are mediated by geographical distance, exploiting the spatial variation stemming from the country's size and archipelagic nature. We find that regions located farther from Jakarta experienced delayed electrification, with geographic remoteness and fragmented infrastructure emerging as key constraints. Differences in power supply development, population density, per capita GDP, and landscape complexity further explain variation in electrification speed. Using a simulation exercise, we show that some eastern provinces could have reached a 50 % electrification rate up to 26 years earlier if they had shared the structural characteristics of Jakarta. Our findings underscore the importance of within-country spatial heterogeneity in understanding electricity diffusion and highlight the policy relevance of targeting local barriers to accelerate access. The study contributes to global electrification research by documenting diffusion patterns at subnational scale in a lower-middle-income country and offers a replicable framework for assessing spatial inequality in electricity access.