Why should we switch to renewable energy? What are the different energy sources, their characteristics, advantages and disadvantages?

Renewable energy is an important alternative to fossil fuel depletion and environmental pollution. Learn about the characteristics, advantages and disadvantages of different energy sources.

 

Televisions, cars, cell phones, computers. These are all products that make our lives more convenient and enriching. In order to use these products, we need energy. Until now, we’ve been using resources that are readily available in nature, such as coal and oil. However, we can all agree that these resources are becoming increasingly scarce. In addition, most of the fuels we’ve been using are fossil fuels, which produce carbon dioxide and other pollutants, and are often blamed for environmental pollution. Based on these facts, renewable energy is being researched. In this article, we’ll look at the meaning and types of renewable energy, as well as their characteristics, advantages, and disadvantages.
Before we talk about renewable energies, let’s take a look at the word energy. According to the dictionary, energy is the power underlying human activity, the ability to do physical work. Everything we see, hear, touch, and use requires energy.
But what is renewable energy? In English, it means “new & renewable energy,” which means new and renewable energy. Renewable energy is energy that is converted and utilized from existing fossil fuels or renewable energy that is converted and utilized from sunlight, water, geothermal energy, biological organisms, etc. In Korea, a total of 11 fields are designated as renewable energy, including three new energy fields and eight renewable energy fields.
You may have heard of fuel cells from the recent release of hybrid cars. A fuel cell is an indirect reaction of different substances through a semi-permeable membrane that converts energy into electricity. A typical example of this energy is hydrogen fuel cells. It combines hydrogen and oxygen to make water and converts the energy generated into electricity. It’s similar to a battery in that it generates electricity through a chemical reaction, but unlike a battery, it doesn’t need to be charged because the hydrogen and oxygen are supplied externally. In addition, because it generates energy without combustion of fuel, unlike conventional internal combustion engines, there are no pollutant emissions, carbon dioxide emissions can be dramatically reduced, and it is almost silent. Energy efficiency is also 50%, which is higher than conventional internal combustion engines (30%). However, it is not a clear alternative energy source because it converts and uses existing energy.
Hydrogen energy is the direct combustion of hydrogen with oxygen and utilizes the energy generated. Hydrogen is converted into water by combining with oxygen, so there is no environmental pollution from exhaust, and it generates more than three times the energy of the same mass of oil. Interest in hydrogen began to grow in the 1970s when the oil crisis spurred research into alternative fuels, and it is now being recognized as a clean fuel that can contribute to environmental protection. Hydrogen gas is difficult to manufacture and store, but some metals, including magnesium, contain metal hydroxides that absorb hydrogen well, and these alloys have the property of releasing hydrogen when the pressure is reduced by applying a certain amount of heat, so they can be adsorbed onto metal powders that absorb hydrogen well, and there are no major difficulties in transportation or storage. Currently, several methods of producing hydrogen are being studied.
Coal-to-liquids gasification is a method that refines solid coal or petroleum and liquefies or gasifies the remaining low-grade raw materials into a new power source. This energy is highly efficient compared to conventional sources. It is also a very eco-friendly technology with low emissions of polluting sulfur oxides and nitrous oxides, and it can synthesize low-grade, non-reusable raw materials into new, high-value-added products. However, it requires a large investment in infrastructure.
Biomass energy involves the pyrolysis or fermentation of living organisms to harvest fuels such as methane, ethanol, and hydrogen. It utilizes the energy or organic raw materials that are produced when microorganisms break down the fluids of animals and plants into inorganic substances. Direct uses of biomass include cooking rice from dry leaves or straw, running steam trains or cars over wood fires, and lighting the dark with torches, while conversion uses include burning wood to make charcoal, using microorganisms to make alcohol, producing methane gas, and composting grass or straw to make compost. However, the efficient production of biomass energy requires large areas of land, and the amount of energy generated varies from region to region, making it difficult to commercialize.
Solar energy has been studied and commercialized for a long time. It is a method of generating energy by utilizing the heat that radiates from the sun and reaches the earth. It can be used for direct heating by collecting the heat in one place, or for solar power generation by boiling water using a heat exchanger and turning a turbine with high-pressure water vapor to generate electricity. This energy has the advantages of being an inexhaustible source of energy as long as the sun radiates heat, emission-free energy with no greenhouse gas emissions, less localized production than conventional fossil fuels, and a wide range of applications and uses. However, there are challenges, such as the small amount of energy available per unit area, the fact that solar energy is not always available, such as on cloudy or rainy days, and the fact that it is currently uneconomical compared to the cost of oil.
Geothermal energy takes advantage of the phenomenon that everywhere on Earth, the temperature increases as you go underground to obtain hot water or steam. Sometimes water seeps near hot rocks and turns into steam, which can be used to turn power turbines to generate energy or to heat greenhouses or homes with hot water that is less than 100 degrees Celsius, obtained at a depth of two to three kilometers below the surface. Geothermal energy can benefit local economies not only by generating energy, but also by attracting tourists to the surrounding area by commercializing hot springs. However, there are limited areas where geothermal energy can be developed, and there are safety concerns near these areas due to tectonic movements.
There are four types of ocean energy that can be harnessed from seawater. These are wave energy from waves, tidal energy from rising and falling tides, tidal energy from tidal currents in narrow straits, and energy from ocean temperature differences. Of these, tidal energy is a power generation technology that utilizes the rising and falling motion of the sea level to generate electricity, and it works by trapping the tide and releasing it at low tide to turn a generator. The west coast of Korea has a good location due to the large difference between the tides. Tidal power plants are expensive to build, but once built, they require no fuel, unlike thermal or nuclear power plants. No fuel means no pollution, which makes it a great way to generate clean energy. Although it’s currently not economically viable, tidal power could become competitive in the future when oil becomes scarce and expensive.
In addition to newly developed energy sources, there are also renewable energy sources that have been around for a long time. Water wheels, windmills, and ship sails are just a few examples. These are wind power and hydropower.
The first is wind power, which is the conversion of wind into electrical energy, and there are more than 20,000 of them in operation around the world. They have a propeller with two or three blades, and the wind turns the propeller to generate electricity. This electricity is fed through a pylon to a storage battery. Wind turbines are installed in windy areas, and the weight, length, and shape of the blades are designed to maximize energy efficiency. Wind power is environmentally friendly and quiet, but because the wind doesn’t blow consistently, the amount of power generated fluctuates and the initial installation cost is low.
Hydropower is a technology that harnesses the potential energy of water to generate electricity. It works by turning a turbine and harnessing the energy generated when water falls from a high place to a low place. Compared to other energy sources, hydropower is denser and has a lower cost per unit of electricity generated, but it can destroy the natural environment and cause environmental problems, such as flooded areas.
There are other renewable energy sources such as industrial waste, cogeneration, and nuclear fusion. The main reason why these renewable energies are becoming more and more popular is that fossil fuels, the energy source we have been using until now, are becoming less and less. According to the Korea Institute of Energy Technology, the current estimated fossil fuel reserves will be depleted in 40 to 60 years, which means that we need to have a reliable alternative energy source in at least 40 years. Nuclear power was thought to be the main alternative, but events such as the tsunami in Japan have cast doubt on its safety. Another reason is that renewable energy is an environmentally friendly source of energy. The Kyoto Protocol, adopted in 1997, aims to minimize and reduce greenhouse gas emissions. Korea was not part of it at the time, but has been required to join since 2008. South Korea, which once ranked ninth in the world for annual carbon dioxide emissions, needs to invest more in renewable energy development.
Renewable energy still accounts for less than 10% of the world’s electricity supply, largely because it is not as economically viable as fossil fuels due to high production costs and difficulties in developing technologies for storage and transportation. However, with institutional mechanisms such as voluntary Renewable Power Agreements (RPAs) and Renewable Portfolio Schemes (RPSs) in place, and ongoing technological developments, renewable energy sources are likely to replace fossil fuels in the near future.