Power at 200 meters
Solar panels on rooftops. Wind turbines on hilltops. Renewables joining a power grid that still runs, at its core, on coal and gas. The targets sound good: 35% clean energy by 2030, 50% by 2040. Meantime, electricity remains expensive and reserves thin for a growing economy.
Perhaps we are looking in the wrong direction. Maybe the answer is not above us, but below. Last December, scientists from the University of the Philippines Marine Science Institute (UP MSI) went deep into the southern Philippine Seas. I believe what they found changes everything.
Where they went, the temperature difference between warm surface water and cold deep water is large enough to generate electricity at just 200 meters down. Everywhere else in the world, you need to go maybe 800 to 1,000 meters to get the same result. They got there in a quarter of the distance.
Here is how it works. Warm water sits near the surface, where it gets more exposure to the sun. Cold water sits far below. That temperature difference, at least 20 degrees Celsius between top and bottom, can drive a turbine the same way steam drives an engine. Except the ocean is the boiler, and it never runs out of fuel. This is called Ocean Thermal Energy Conversion, or OTEC.
In reporting on their discovery, Dr. Charina Lyn Amedo-Repollo, who leads the Physical Oceanography and Observation Laboratory at UP MSI, said: “The strong surface-to-deep temperature contrast observed in the southern Philippine Sea meets the thermal requirements for OTEC, indicating high potential for continuous baseload renewable energy.”
That last phrase, “continuous baseload,” is the one that matters most to me. Solar power stops when the sun goes down. Wind power stops when the air is still. Without enormous and expensive batteries, neither can guarantee that the lights stay on around the clock. OTEC can. It can provide baseload power, like plants that run on coal and natural gas. It can run day and night, rain or shine, storm or calm. It is the clean energy source that works like a regular power plant: always on, always producing.
And, from what I have gathered, the 200-meter finding is not a small detail. The pipe that pulls cold water up from the deep is the most vulnerable part of any OTEC system, especially in a country hit regularly by typhoons and earthquakes. A shorter pipe can be a stronger pipe. What was once an engineering problem too expensive and too risky to solve becomes, at 200 meters, a problem we can actually tackle. We would not have to go 1,000 meters deep.
The MSI team found more than just a useful temperature gap. They also mapped unknown earthquake faults off Palawan, an area long thought to be geologically safe, and found underwater volcanoes in the Sulu Sea releasing gases from the seafloor.
In a talk regarding the discovery, Dr. Fernando Siringan, who leads the Geological Oceanography Laboratory, said that “anywhere you have gas seeps and hydrocarbon seeps, the biodiversity is relatively unique, that’s why it’s an area of interest for both geologists and biologists.”
The Palawan fault discovery actually strengthens the case for OTEC. If we are weighing nuclear plants or expanded gas pipelines against the background of hidden earthquake risks, a technology that uses nothing but ocean temperature, with no radioactive fuel and no volatile gas, starts to look not just clean but safe.
Admittedly, OTEC is expensive to build. That is why it has not been commercially pursued. The pipes, platforms, and machinery account for more than half the upfront cost. Studies indicate that the price per unit of electricity has historically been higher than what comes off the current grid.
But at the same time, that cost does not discount the cost of negative externalities such as the health burden of breathing air polluted by coal plants. It does not discount the economic risk of buying coal from other countries at prices we cannot control. And it does not consider the 200-meter advantage the MSI researchers have just discovered.
Factor all of that in, and maybe an OTEC plant will look like a reasonable investment for a country that needs power it can count on. Researchers, energy experts, and policymakers will all have to weigh in on this. But, to date, there are positive indicators that OTEC may now be feasible.
OTEC also produces clean drinking water as a byproduct. Desalination is part of the OTEC process. Warm surface seawater enters a low-pressure vacuum chamber where it flashes to steam, leaving salt behind. The pure steam drives a turbine for power, then condenses using cold deep water, yielding desalinated freshwater alongside electricity.
My understanding is that the cold water OTEC pumps up can also be used for growing high-value seafood. Thus, in remote parts of Mindanao or along the eastern coast, an OTEC plant is not just a power source. It is also a water supply and a food system. OTEC thus becomes a lifeline.
What is holding back OTEC is not the science, not the geography, but the lack of support for more marine science research. To further determine viability, a pilot plant must be established. MSI has done its part by identifying suitable locations. Further research can help generate data that will help policymakers make an informed decision.
Further to this, we need a national pilot program targeting the southern Philippine seas so that we can turn this research into an actual power plant, or a government policy that treats Ocean Thermal Energy Conversion as a strategic national priority rather than just an interesting science project.
Think of it this way: the southern Philippine seas are strategic energy reserves. The power is there, at 200 meters below, waiting to be tapped. The only thing missing is government foresight and the will to go get it. With state policy and support in place, the private sector will not be far behind with funding.
Marvin Tort is a former managing editor of BusinessWorld, and a former chairman of the Philippine Press Council.
