In this blog post, we examine the background behind Japan’s relentless claims to sovereignty over Dokdo, as well as the resource-related and geopolitical reasons hidden behind them.
Recently, controversy has arisen as various South Korean plastic surgery clinics, corporations, and even district office websites have labeled the “East Sea” as the “Sea of Japan.” Japan’s absurd and baseless claims have persisted to this day, and the question of whether it is the “East Sea” or the “Sea of Japan” has become a sensitive issue for the people of South Korea. At the heart of the territorial dispute with Japan centered on the East Sea lies the small island of Dokdo. So, what is one of the reasons Japan is targeting Dokdo, our territory proven by history? It would not be an exaggeration to say it is because of the approximately 600 million tons of “burning ice,” or gas hydrates, buried around Dokdo.
Gas hydrates are solids formed when gas and water combine under low temperatures and high pressure, forming a three-dimensional structure through hydrogen bonds between water molecules. Methane and carbon dioxide are trapped within this three-dimensional structure of water molecules, and the part we use is the carbon compounds inside. Gas hydrates are highly energy-dense (efficient) because a small volume can yield a large volume of fuel. The estimated global reserves of gas hydrates are approximately 10 trillion tons, nearly double the amount of fossil fuels currently in use, and they are widely distributed. Burning the methane captured in hydrates produces significantly less pollution and CO2 than conventional fossil fuels, making it an environmentally friendly option.
So, is there a way to capture (collect) this highly efficient future resource? Since gas hydrates are primarily composed of water and gas, and the part we use is the gas, transporting the water (ice) along with it would be inefficient. Therefore, instead of mining the solid gas hydrate itself, methods are being researched to induce the dissociation of hydrates underground and capture the gas released during that process. Currently proposed technologies include depressurization, hot water injection, and inhibitor injection.
First, the depressurization method is used when a free gas layer exists near the hydrate layer. Drilling a hole into the free gas layer reduces pressure, which in turn lowers the pressure in the adjacent gas hydrate layer. As the pressure drops, the gas hydrate, which was in a solid state, separates into water and gas; the gas generated at this time is collected and brought to the surface. This method utilizes the phase change of a substance in response to pressure, but it has the limitation that it cannot be used if there is no adjacent free gas layer.
Thermal injection is a method that can be used even in the absence of an adjacent free gas layer. A hole is drilled into the hydrate layer, and hot water is injected through the drill pipe. As the temperature rises, dissociation is induced—similar to the depressurization method—causing the hydrate to separate into gas and water. The gas is then captured using the same method.
Finally, there is the inhibitor injection method. This involves injecting an inhibitor into the hydrate layer to induce dissociation. In Siberia, methanol injection has been used to dissociate gas hydrates and increase gas production, and methods involving the injection of glycol and calcium chloride have also been tested. When developing gas hydrates in the ocean, the brine injection method is effective because seawater is readily available. However, this method poses environmental pollution concerns and is limited by the high cost of the large quantities of solvent required.
As such, there are various methods for capturing hydrates. Yet we still drive cars using gasoline and generate electricity by burning oil. Why aren’t we using gas hydrates? The answer is not that we “don’t” use it, but that we “can’t” use it. Like other next-generation energy resources, gas hydrate extraction has not yet reached the practical application stage. The biggest problem is stability during extraction. Gas hydrates exist under low-temperature, high-pressure conditions in the deep sea, but when brought to the surface, the pressure drops and their molecular structure breaks down. If methane and other gases are released into the atmosphere at this point, they could actually accelerate global warming. Another major concern is ground subsidence. Since gas hydrates are buried deep in the ocean, extracting them leaves the area that originally supported the seabed hollow, creating a risk of ground collapse. However, reports indicate that progress is being made in developing measures to address issues such as leakage and stability during extraction. With advancements in science and technology, the day when gas hydrates are utilized as a major energy source appears to be drawing near.
