The Commission on Volcanology conducted an exploration of the Tiwi geothermal field from 1964 to 1968.

[2] The Philippine government in early 1971 invited the Union Oil Company of California (Unocal) to form the Philippine Geothermal, Inc. (PGI) which is intended as a joint venture for the exploration and development of geothermal energy.

A service contract was made with the state-owned National Power Corporation (NPC) on September 10, 1971.

PGI contributed technical knowledge as well as a portion of the Tiwi field's exploration and development.

[6] The Tiwi Geothermal Field is divided into four geographical areas: Naglagbong, Kapipihan, Matalibong, and Bariis.