Some geologists risk their lives working on volcanoes, sometimes needing to conduct experiments right inside an active crater, that include collecting rock, water and gas samples, measuring in situ parameters such as water temperature of boiling mud, recording phenomena such as sulfur gas and carbon dioxide emissions, and analyzing the nature of ground fractures and faults. 

They do this with the aim of trying to understand the behavior of the volcano, which eventually would contribute greatly to efforts in hazard mitigation, disaster risk reduction and preparedness. Others however study volcanoes, active or not, for the purpose of evaluating their potential for geothermal energy.

The war-induced energy crisis currently being experienced worldwide only highlights the importance of harnessing renewable sources of energy like the radiation from the sun (solar energy), strength of the wind (windmills), inertia of water in rivers (hydroelectric power), and heat from the “bowels of the earth” or more technically called geothermal heat (geo-earth, thermal-heat), among others.

The location of the Philippines near the equator and the presence of numerous volcano-producing geological systems make the Philippines an ideal setting to develop solar and geothermal energy sources.

Volcanoes and geothermal energy

Volcanoes form when molten rock, or magma rises to the surface. Magma can originate from several tectonic mechanisms, including by subduction (when one tectonic plate dives underneath another, by continental rifting and oceanic spreading), when two plates split away from each other, or when there is a constant source of heat underneath the earth called a hot spot. The Hawaiian Islands and the Yellowstone Caldera in the northwest United States are the result of hot spot volcanism, while the volcanoes of Eastern Africa such as those in Kenya and Ethiopia are caused by rifting.

The numerous undersea volcanoes of the East Pacific Rise and the Atlantic Ridge system are formed by oceanic spreading, while the volcanoes of archipelagos like Japan, New Zealand, Indonesia and the Philippines are mostly formed by subduction.

When groundwater is heated by rising magma or nearby hot rocks, it becomes more mobile especially when the rocks that contain it are permeable. Permeability is often a function of the degree of fracturing of rocks usually by faults.

Faults are often feared by many, as they associate them usually to disastrous earthquakes. But faults are what geothermal energy explorationists look for in a prospect, in addition to the hot circulating fluids. When magma or hot rocks, faults and groundwater co-exist, a geothermal system is created.

The heated waters can then be extracted through controlled pipes drilled into the ground, with the pressure of their steam harnessed to run turbines that can eventually generate electricity. So long as the dynamism of the Earth persists, volcano-forming processes such as subduction, rifting, oceanic spreading and mantle plume hotspots will continue to operate.

And while such processes operate, heat provided by magma from deep beneath the earth will continue to exist. In this sense and at this scale, geothermal heat as a source of energy is limitless and independent of atmospheric conditions such as sunlight (solar power) and wind strength (windmills).

Develop more geothermal plants

Geothermal sources currently contribute only around 10% to the Philippine energy mix, with coal — an environmentally unfriendly source — remaining as the dominant contributor, while the rest of the renewable sources are shared mainly by hydropower, solar and wind.

But with more than 20 actives volcanoes, more than 40 potentially active volcanoes and hundreds of geologically young volcanic centers, the Philippines has a great potential to develop geothermal energy to become a major contributor to the national energy mix.

If properly planned and with sufficient government support, the Philippines may be able to regain its position as the world’s second-largest geothermal producing country by megawatt capacity, after it lost the place to Indonesia only several years ago. – Rappler.com

Mario A. Aurelio, PhD is a professor at the National Institute of Geological Sciences – University of the Philippines (UP NIGS). With his team at the Structural Geology and Tectonics (SGT) Laboratory of UP- NIGS, he conducts research on the importance of geologic structures such as faults in the development of geothermal systems.