In this blog post, we explore how renewable energy can overcome the limitations of fossil fuels and create a sustainable future.

Renewable Energy: The Power Illuminating the Future

Televisions, cars, mobile phones, computers. All these products make our lives more convenient and comfortable. However, using these products requires ‘energy’. Until now, energy has been supplied using resources like coal and oil, but most agree these resources are gradually depleting. Furthermore, the fuels used thus far have mostly been fossil fuels, which emit carbon dioxide and other pollutants, making them a primary cause of environmental pollution. For these reasons, renewable energy is being researched as an alternative. This article explores the meaning and types of renewable energy, examining the characteristics and pros and cons of each.
First, let’s look at the concept of ‘energy’. Energy signifies the fundamental force behind human activity—the ability to perform physical work. Energy is essential for all actions we see, hear, touch, and use.
So, what exactly is renewable energy? Known in English as “new & renewable energy,” it refers to energy derived from converting existing fossil fuels or utilizing renewable resources such as sunlight, water, geothermal heat, and biomass. It represents a future-oriented energy source for a sustainable energy supply system. In South Korea, a total of 11 categories are designated as renewable energy, including 3 new energy sources and 8 renewable energy sources.

Types of New & Renewable Energy

Fuel Cells

Fuel cells generate electricity by indirectly reacting different substances through a semipermeable membrane. Hydrogen fuel cells are a prime example. They convert the energy released when hydrogen and oxygen combine to form water into electrical energy. Unlike batteries, fuel cells do not require charging because they receive hydrogen and oxygen externally. They generate energy without combustion reactions, thus emitting no pollutants and significantly reducing carbon dioxide emissions. Their energy efficiency is also high at 50%, compared to conventional internal combustion engines (30%). However, strictly speaking, they are not a complete alternative energy source because they convert and use existing energy.

Hydrogen Energy

Hydrogen energy is a method of obtaining energy by combusting hydrogen with oxygen. Since hydrogen combines with oxygen to reduce into water, there is no environmental pollution from exhaust gases, and it produces approximately three times more energy than petroleum of the same mass. Following the oil crisis of the 1970s, research into alternative fuels intensified, increasing interest in hydrogen energy as a clean fuel. While hydrogen has the drawback of being difficult to manufacture and store, methods are being researched to store and transport hydrogen by adsorbing it onto certain metal hydroxides, such as magnesium.

Coal Liquefaction and Gasification

Coal liquefaction and gasification are methods of converting solid coal or low-grade residues from refining into liquid or gaseous forms for energy use. They offer high efficiency and are environmentally friendly technologies with low emissions of sulfur oxides and nitrogen oxides. While they have the advantage of converting low-grade residues into high-value products, they require significant investment in basic infrastructure.

Biomass Energy

Biomass energy involves obtaining methane, ethanol, hydrogen, etc., by pyrolyzing or fermenting biological matter. Biomass utilizes energy released when microorganisms decompose plant and animal organic matter or employs organic raw materials. It is used to generate heat by burning firewood or straw, or to produce compost. However, efficient biomass production requires large tracts of land, and significant regional variations in energy yield pose challenges for commercialization.

Solar Thermal Energy

Solar thermal energy utilizes heat radiated from the sun for heating or power generation. It either harnesses concentrated high-temperature heat or boils water to produce high-pressure steam that drives turbines to generate electricity. It offers the advantages of being a pollution-free energy source with minimal regional bias. However, its use is limited on cloudy days, and the energy cost per unit is relatively high.

Geothermal Energy

Geothermal energy utilizes heat from deep underground to produce hot water or steam. This thermal water is used for heating or power generation and can contribute to the local economy through tourism effects from hot spring development. However, areas suitable for geothermal energy development are limited, and safety concerns exist due to potential crustal movements.

Ocean Energy

Ocean energy harnesses the power of waves, tides, currents, and temperature differences in the sea. Tidal energy, in particular, is a technology that generates electricity using the rise and fall of the sea level, making it suitable for areas with large tidal ranges, like the west coast. Tidal power generation has high installation costs but incurs no fuel expenses, making it a highly regarded eco-friendly energy source. While currently less economically viable, it could become competitive if fossil fuel prices rise.

Wind Power and Hydropower

Wind power generation converts wind into electrical energy. It causes no environmental pollution but suffers from significant fluctuations in output depending on wind volume and has high initial installation costs. Hydropower utilizes the potential energy of water, offering low generation costs and high energy density. However, it carries risks of environmental destruction due to the creation of flooded areas.

Conclusion

As examined above, various renewable energy sources are gaining attention because existing fossil fuels are diminishing. According to the Korea Institute of Energy Research, they are expected to be depleted within the next 40 to 60 years. Furthermore, renewable energy is environmentally friendly. The 1997 Kyoto Protocol adopted the goal of reducing greenhouse gas emissions, and accordingly, South Korea has been required to reduce its emissions since 2008. As the world’s ninth-largest annual carbon dioxide emitter, South Korea needs to invest more in renewable energy development.
The reason renewable energy still accounts for less than 10% globally is due to high production costs and the difficulty of technological development. However, with institutional mechanisms like the Renewable Portfolio Standard (RPS) and Renewable Energy Supply Agreements (RPA), along with steady technological advancement, the potential for renewable energy to replace fossil fuels is growing.