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Tuesday, June 01, 2004
Geothermal power brightens RP future
By Henrylito D. Tacio
THE Philippines is home to more than 200 volcanoes, 21 of which are active. A volcano is considered active when it has erupted within the last 600 years while dormant volcanoes are those than has not erupted in 600 years.
Among the active volcanoes in the country are Mayon, Taal, Hibok-Hibok, Banahaw, Pinatubo, Biliran, Iraya, Iriga, and Matutum. These volcanoes can be tapped as sources of geothermal power.
"As the Philippines pole vault into the 21st century, the nation can look forward to geothermal energy to remain as one of the pillars of its energy self-reliance program," commented Arturo P. Alcaraz and M. Ogena, both Filipino geothermal experts.
The two experts noted that geothermal energy as an indigenous energy resource provides the country a sustainable option to other conventional energy sources such as solar, wind, and biomass.
After the United States, the Philippines is the world's largest user of geothermal energy for power generation with 1,909.23 megawatts of installed capacity.
In 1999, for instance, geothermal power plants generated a total of 10,577 gigawatt-hours of electricity.
Geothermal plants in the Philippines generate about a fifth of the national electricity supply from six fields, with 11 areas of production.
The fields, spread throughout the islands, are at Mak-Ban (Makiling-Banahaw in Laguna), Tiwi (in Albay), Bac-Man (Bacon-Manilto in Sorsogon), Tongonan (in Leyte), Palinpinon (in southern Negros), and Mindanao (in Cotabato).
In Greek, geo means "earth" and thermos means "heat." Literally, geothermal implies "heat from the earth."
Its steam comes from raindrops that seep down the cracks of the earth until it reaches a rocky reservoir two to three kilometers deep, where it is heated by the earth's core of hot rocks or magma, which transform the water into steam.
According to the country's geothermal task force, the heat source of the geothermal energy is the magma, which comes close to the earth's surface in some places. The heat in a geothermal system can be harnessed in the form of steam or with water as the medium.
"Deep holes are drilled down to the reservoirs and pipes are inserted in these holes," explains The Geothermal Handbook on how geothermal energy is generated. "The mixture of hot water and steam, under its own pressure, will flow up the pipe.
"Upon reaching the surface," the handbook continues, "the water and steam go through a separator which sends the steam by way of a pipeline to the power plant, passing through scrubbers and catalysts to make it as pure as possible.
The hot water, on the other hand, is sent via another pipe to a reinjection well where the water is sent back to the geothermal reservoir.
"The powerful natural steam, still under pressure, is directed into the power plant where it spins the blades of a turbine. Attached to the turbine is a generator, a tightly coiled wire cylinder which rotates in a field of magnets surrounding it.
"This rotation process generates electricity, and the electric current is then sent from the transmission lines into homes, offices and other business establishments, factories and schools."
In the Philippines, geothermal plants are using the reinjection scheme to prevent geothermal fluids -- the water used in generating electricity from the geothermal steam -- from escaping and to recharge the reservoir, thus making the resource renewable.
Pipelines carrying the fluids are insulated and tightly closed to protect the environment. And to assure a continuous supply of steam, geothermal operators safeguard thousands of hectares of watersheds, thus preserving nature for future generations.
Utilization of geothermal energy for power generation started in Lardello, Italy in 1903 when Prince Piero Ginori Conti decided to hook a generator to a steam engine driven by the natural steam.
The success of this operation (after so many innovations) led to the installation of the world's first geothermal power plant, with capacity of 250 kilowatts, in 1913, in the same site. The geothermal field is still operating and is a favorite tourist attraction.
(June 1, 2004 issue)
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