In 1986, geothermal power in the Philippines was no longer just a technical curiosity. It had become an economic experiment with regional implications, especially as the country looked for ways to leverage its volcanic resources to meet both domestic demand and—where possible—export power to neighboring islands. For policymakers and analysts, measuring the reach and significance of these early export projects requires a close look at ISIC 3510—electric power generation, transmission, and distribution—a statistical category broad enough to include every generator but specific enough, if filtered properly, to reveal the geothermal sector’s footprint.
The starting point is to extract a registry of ISIC 3510-coded firms operating power generation facilities in the Philippines in the mid-1980s. Most are easily identified as public utilities or private concessionaires, but the subset operating geothermal plants is smaller and often more specialized. Project lists published by the National Power Corporation (NPC), the Department of Energy, or energy sector trade associations are invaluable here. The major geothermal fields—Leyte, Makiling-Banahaw, and Tongonan, among others—were run by joint ventures or subsidiaries established for geothermal development, sometimes with international partners.
Once the population of geothermal operators is established, the next step is to document plant output. This typically means collecting annual generation figures—usually reported in megawatt-hours—from NPC reports, plant operator filings, or energy yearbooks. These figures often break down output by plant and, sometimes, by end-use: local grid supply versus exported power.
Tracking export projects, however, requires following the flow of electricity beyond the plant fence. In the Philippines’ archipelagic context, this almost always meant submarine cable projects—connecting geothermal-rich islands (like Leyte) to neighboring demand centers (such as Cebu or even Luzon). Energy infrastructure maps and project documentation from the period, including technical reports and government press releases, usually note the commissioning dates and capacities of these interconnections.
To correlate geothermal plant output with exports, analysts should overlay plant-level generation data with transmission project milestones and operational reports. In years when new submarine cables were completed, a visible jump in “exported” power from certain geothermal plants is expected—sometimes tracked as a separate line item in energy agency statistics. Cross-referencing with import data from the receiving islands (i.e., how much of their power was sourced from remote geothermal projects) helps confirm the physical flow.
Another useful step is to examine policy context and contractual arrangements. Some early projects were motivated by government targets to reduce oil imports or to stabilize power in less-developed islands. Power purchase agreements, regulatory filings, and even World Bank or Asian Development Bank project summaries provide insight into the economics and politics of exporting geothermal energy within the Philippines.
There are always complexities: not all generation classified as “export” made it reliably to its destination, especially in years with cable failures, grid disruptions, or unexpected demand spikes. Documentation of all assumptions—about firm classification, transmission project status, and allocation of generation to export versus local use—is essential to any robust analysis.
By layering ISIC 3510 firm records, plant output data, and detailed infrastructure maps, analysts can reconstruct the early story of geothermal export projects in the Philippines. The trends are uneven, shaped by resource availability, investment cycles, and the realities of operating in a fragmented archipelago, but the outlines are clear. What emerges is a snapshot of innovation—geothermal plants not only powering local industry and homes, but also laying the groundwork for a more interconnected, resilient national grid.