Geothermal is good, but…

The problem with geothermal power is we don’t have enough. We only have 1,900 MW of it feeding into our power grid. That’s all the commercially proven geothermal resources we have as of now. The Lopez Group, the Sy-blings and Aboitiz Power, among other groups are trying to see if we have more. Looking for it is an expensive and risky endeavor that’s plagued with community issues. But it is being done.

We are in the Pacific Ring of Fire and it is easy to assume that with all the volcanoes around, geothermal should be contributing more to our power grid. Not because there is a volcano in an area means there is usable geothermal resource available. For instance, I recall that EDC, when it was still under PNOC, drilled in the Mt. Pinatubo area some years before the eruption. They found the heat they were looking for but no permeability in the rock to allow heated underground water up to the surface as steam to power a geothermal plant.

Before I left PNOC, I recall asking the EDC technical experts if we have more geothermal resources in the country that we can tap. The answer was that we have discovered and developed about as much of the resources that they think we have. So, I was not surprised when after the Lopez Group took control of EDC, they ventured to explore for geothermal resources in Chile and Peru. They have the technical experts on the payroll and not much more to do here at home.

Geothermal energy is based on tapping Earth’s natural warmth heating underground water reservoirs, sometimes to several hundred degrees. That hot water can be used to produce steam and power generators. The cold water is then pumped back underground. Geothermal projects used to depend on finding the right natural conditions: areas where hot water naturally comes up from below the ground. There are not too many of those easy finds.

Technology to the rescue!  Texas Tribune reports that a startup called Sage Geosystems used fluid to create cracks in the rock deep below the surface in an abandoned natural gas well, a technique similar to fracking for oil and gas. Then they pumped 20,000 barrels of water into the two-mile-deep well. The cracks absorb the water, and the stone heats it up. Hours later, an operator opened the well from a control room. Pipes above ground shook as the pressurized water gushed back up. The water spun small turbines, generating electricity.

Sage now says there’s a lot more geothermal power to be had by pumping fluid through hot rock where there is no natural water.

The website cooldown.com reports that “Sage isn’t the only company pursuing this avenue. Fervo Energy is experimenting with creating two parallel wells, one to pump water down and one to bring it up, while Quaise Energy is using microwaves to drill into hotter areas than traditional drilling equipment can withstand.”

Back here at home, EDC says they are also using new technologies in geothermal energy.

“Early this year, EDC tapped GreenFire to use its patented technology to essentially generate power from non-productive geothermal wells that would otherwise have been shut off or even plugged. This will allow EDC to extend the useful life of some (but not all) of its aging, declining and non-productive wells.

“As a geothermal well ages, it is not uncommon for its productivity to drop below levels that would be considered as commercially viable or sustainable. This deterioration in production capacity could be a result of changes to the natural properties of the underground geothermal reservoir…While such wells are no longer ‘productive’ in the conventional sense, they still possess significant heat underground that can be harnessed for energy given the appropriate technology.

“GreenFire’s GreenLoop is basically a heat exchanger that is lowered into the well to act as an underground boiler. This ‘boiler’ then produces steam either from the boiling of fresh water that is fed into the GreenLoop at the surface, or from boiling some other motive fluid or refrigerant… this technology will allow EDC to continue to generate power from wells that would have otherwise been shut off… GreenLoop is best used for extending the productivity of a well towards the end of the well’s life…”

Good as geothermal is, it is not totally benign. Specially with the use of fracking technology, it faces the same concern about triggering earthquakes. In 2006, a pilot geothermal plant in Switzerland caused a magnitude 3.4 earthquake that damaged buildings and led to the plant’s closure. In 2017, a magnitude 5.5 earthquake linked to a pilot geothermal project in South Korea injured dozens.

I remember the late Energy Minister Ronnie Velasco calling the PNOC EDC technical experts to his office after being told of geothermal drilling’s potential for creating earthquakes. He said, instead of leaving a legacy as the father of geothermal energy in the country, he might be known as the father of earthquakes.

The geologists and other experts reassured him the chance is remote. But that was before the Swiss and South Korean experiences. Indeed, there were suggestions that PNOC drillings in the Pinatubo area may have triggered the eruption. But experts dismiss such thoughts as not likely.

In short, geothermal is good, dependable, clean energy but not without risks.

Boo Chanco’s email address is [email protected]. Follow him on X @boochanco.