In this blog post, we take an in-depth look at the potential and practical applications of geothermal energy amid the energy crisis and environmental challenges.
The time is coming when humanity must prepare to part ways with fossil fuels, which have been part of our lives for over a century. The global population surpassed 8 billion on March 1, 2024, and the rate of population growth is predicted to continue accelerating for some time. Consequently, global energy demand is increasing exponentially, and existing fossil fuel-based energy systems are showing limitations in consistently meeting this demand. Furthermore, as concerns about climate change and environmental pollution grow, reducing our dependence on fossil fuels and finding more sustainable energy resources has become an urgent priority.
Energy is essential for human survival, and for the past century or so, most of our energy has come from fossil fuels such as oil, coal, and natural gas. However, these fossil fuels are non-renewable resources, and studies indicate that their reserves are gradually depleting, suggesting they will only last another 30 to 100 years. This presents both a major crisis and an opportunity for humanity. This is because, through the process of developing new energy sources and innovating existing energy usage methods, humanity can build a better future.
In this context, renewable energy has begun to emerge, and research is actively underway to develop various forms of energy sources and increase their efficiency. While energy sources such as solar, wind, and hydroelectric power are already widely used, geothermal energy—which is relatively less known—is now gaining attention. Geothermal energy is a source of energy that utilizes the heat from the Earth’s interior, offering unique advantages distinct from other renewable energy sources. Although research on geothermal energy has not yet been extensive, this technology is essential for preparing for an era of energy scarcity.
Looking broadly at the history of geothermal energy, hot springs—which humans have utilized for a long time—can also be included in this category. Hot springs represent the simplest form of geothermal energy use, harnessing naturally occurring geothermal heat. However, strictly speaking, the construction of a geothermal power plant in the village of Larderello in the Tuscany region of Italy in 1904 marks the beginning of geothermal energy in the modern sense. Commercial geothermal power generation began there in 1911, and since then, the sector has grown steadily as numerous geothermal power plants were built in places like New Zealand. As a result, the total global geothermal power capacity reached approximately 16,355 MW in 2023.
As of 2023, the countries with the largest geothermal power capacities are the United States (approximately 3,900 MW), Indonesia (approximately 2,418 MW), the Philippines (approximately 1,952 MW), Türkiye (approximately 1,691 MW), and New Zealand (approximately 1,042 MW). However, rather than simply focusing on the size of the installed capacity, we should pay closer attention to the proportion of geothermal power within each country’s total installed capacity. For example, while the United States ranks first in the world for geothermal power capacity, its total installed capacity is also overwhelmingly the largest globally, so the proportion of geothermal power is relatively low.
In contrast, geothermal power accounts for approximately 30%, 27%, and 25% of total power generation in Iceland, the Philippines, and El Salvador, respectively. Geothermal power, with such a high share, makes a significant contribution to national energy self-sufficiency.
Before exploring the advantages of geothermal energy, it is necessary to first understand its basic principles. While there are many different technologies for utilizing geothermal energy, they can be broadly categorized into direct-use and indirect-use technologies. Indirect-use technologies are employed when the temperature of geothermal water exceeds 150°C, making it easy to produce steam. This method, similar to binary power generation, involves drilling deep into the ground to install two pipes. Water is pumped into one pipe, where it is heated by geothermal energy and turns into steam, rising through the other pipe to drive a turbine and generate electricity. On the other hand, when the temperature of the geothermal water is 149°C or lower, direct utilization technology is used, in which the geothermal water is drawn up and used directly. This is utilized for district heating, greenhouse heating, and other applications, and can also be used for binary power generation. Both technologies can be considered environmentally friendly, with virtually no risk of environmental pollution.
Geothermal energy has many other advantages as well. First, while geothermal energy is similar to other renewable energy sources in that it is renewable, the key difference is that its energy source lies within the Earth. Since geothermal energy utilizes heat from the Earth’s interior, it is not affected by weather conditions, making it easy to predict and enabling stable power generation 24 hours a day. As a result, it has an excellent actual capacity factor and is regarded as a reliable energy source. Furthermore, geothermal energy is environmentally friendly because it produces no waste and is free from various ethical and health concerns. Additionally, since it requires no raw materials, maintenance costs are relatively low.
However, geothermal energy has two critical drawbacks. First, the initial costs are very high. While the construction of a geothermal power plant involves significant equipment costs, the expense of drilling through the ground to install pipes thousands of meters deep accounts for a large portion of the total cost. Second, the areas where it can be installed are limited. Although geothermal energy occurs everywhere beneath the Earth’s surface, it can only generate power efficiently in regions with a high geothermal gradient. Consequently, geothermal power generation is primarily carried out in areas located at plate boundaries, which is why countries such as Iceland, the Philippines, El Salvador, and Indonesia have high geothermal power generation efficiency. Recently, thanks to advancements in indirect utilization technologies, attempts at geothermal power generation have been made in regions relatively far from plate boundaries, such as Germany and Australia; however, the current technological level remains insufficient.
We have examined the history, generating capacity, principles, and pros and cons of geothermal energy. Although South Korea is considered to have low potential for geothermal power generation due to its relative distance from plate boundaries, investment in technological development is nonetheless essential. As South Korea has limited energy resources, investment in renewable and stable energy sources such as geothermal energy is essential for long-term energy security and economic development. To maximize the potential of geothermal power generation, we must actively explore suitable regions and develop technologies to improve generation efficiency. This will be a key factor in determining the nation’s future competitiveness.
