Davao Sur, Batangas eyed as prospective geothermal sites


TWO areas that have high potential to become geothermal facilities have been identified by the Department of Energy (DOE).

Mario Marasigan, director of the DOE’s Renewable Energy Management Bureau (REMB), said these areas are Balut Island in Davao del Sur and Tingloy Island in Batangas.

He said the REMB is continuously doing potential resource assessment that could be offered in the next Open Competitive and Selection Process (OCSP) for hydro and geothermal power.

The DOE is looking for a potential 40 to 50 megawatts (MW) for its low-enthalpy project.

As explained by the International Geothermal Association, “the most common criterion for classifying geothermal resources is that based on the enthalpy of the geothermal fluids that act as the carrier transporting heat from the deep hot rocks to the surface. Enthalpy, which can be considered more or less proportional to temperature, is used to express the heat (thermal energy) content of the fluids, and gives a rough idea of their ‘value’.”

Low-enthalpy geothermal resources are those where the heat content of the fluids range from 80-150 °C.

In the case of Balut Island, Marasigan said they have already offered it in the OCSP but there was no taker because of some market issues.

“Balut itself has very limited consumers and if you develop it, you may just be losing money,” he told reporters.

Meanwhile for Tingloy, being an island, the power should be brought to the main island, Marasigan said.

Balut Island was initially studied via a reconnaissance geologic and geochemical survey in 1997, as part of the National Inventory of Geothermal Resources. It was further studied from 2011 to 2014 as part of the locally funded low-enthalpy project.

The result of integrated geoscientific surveys led to the conclusion that the area hosts a medium to high enthalpy geothermal resource,with an estimated reservoir temp of 200 °C based on gas geothermometers.

The size of the possible resource is estimated at between four to nine square kilometers and estimated to have 10 to 40 megawatts (MW) of geothermal resource potential.

The existence of a possible gas cap is inferred that produces the high temperature and acidic hot springs on the northwest of the island.

Marasigan said that after they identify the areas, they usually conduct regional consultations with concerned local government units (LGUs).

“We ask them [LGUs] if they are willing that their areas be developed or if there are some issues to address,” he said.


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