22/05/2026
The Story of Geothermal Salt-Making in
For centuries, salt-making in the depended almost entirely on the sun. Along the coasts of the archipelago, generations of salt workers practiced the traditional art of pag-aasin—allowing seawater to evaporate slowly under the intense tropical heat until salt crystals formed in shallow salt beds. The process was simple yet laborious, and deeply tied to the rhythms of the dry season.
The writer still remembers seeing some of these traditional salt beds in as a child, while accompanying the contingent on a tour of Central ’s electric cooperatives—a memory that, perhaps, deserves a story of its own one day.
In the Region, however, nature was far less forgiving. Located along the typhoon belt, the region frequently endured powerful storms, torrential rains, and seasonal flooding that repeatedly disrupted salt production. Entire harvests could vanish overnight beneath floodwaters or dissolve under sudden unseasonal rains. In Bicol at the time, —ordinary and abundant elsewhere—became a vulnerable and uncertain commodity.
Yet from these challenges emerged one of the most remarkable, and largely forgotten, scientific achievements in Philippine history.
In the early 1970s, the municipality of Tiwi became the site of a groundbreaking experiment that drew international attention: the world’s first successful geothermal salt-making plant to use the earth’s natural heat directly for industrial salt production.
Nestled within the volcanic landscape surrounding Mount , Tiwi possessed what few places in the world had in abundance—powerful geothermal energy rising from beneath the earth’s crust. Long before geothermal electricity became synonymous with Tiwi, scientists and engineers recognized that the underground steam fields could be harnessed for something more immediate and practical: producing salt regardless of weather conditions
The idea was born during a period of crisis.
In 1972, devastating floods swept across Luzon and the Bicol Peninsula, destroying large portions of traditional salt beds throughout the region. The sudden shortage exposed the fragility of the country’s heavy dependence on seasonal solar salt-making. Researchers from the Commission on Volcanology ( ), who had already begun modest geothermal experiments in Tiwi, accelerated their efforts in response to the emergency.
Their concept was revolutionary yet elegantly simple.
Instead of relying on the sun to evaporate seawater over weeks or months, geothermal steam from deep underground reservoirs would provide continuous heat—day and night, rain or shine. Seawater would be pumped inland from the coast to the geothermal field, where the earth’s natural steam would rapidly boil and crystallize it into salt.
By February 1972, engineers at the Tiwi Geothermal Pilot Plant had successfully demonstrated the process. A pipeline from the sea was laid through Barangay to the COMVOL facility in Barangay , where seawater was transformed into two kinds of salt: ordinary coarse rock salt and a finer, softer iodized variety. The achievement quickly gained national attention. Samples were even sent to , impressing President Ferdinand E. with the innovation and its potential.
Recognizing both its scientific and economic significance, the Philippine government organized a technical panel composed of leading agencies—including COMVOL, the National Power Corporation ( ), and the National Science Development Board ( )—to oversee the development of a full-scale geothermal salt-making project.
🧂First part of a continuing series.
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