In this blog post, we’ll explore the principles of bioethanol, its development across generations, its advantages and limitations, and the current state of research in South Korea.
What Is Bioethanol?
Would you believe it if I told you that corn could power a car? Would you believe it if I told you that fuel could be extracted from decaying wood? Bioethanol is an eco-friendly energy source that utilizes these technologies to replace our dwindling fossil fuel reserves. Bioethanol is a biofuel produced by fermenting glucose—derived from starchy crops such as potatoes and corn—in a process similar to brewing beer or makgeolli, and then blending the resulting ethanol with gasoline for use.
Bioethanol is produced by breaking down the starch in the raw materials to create glucose, which is then fermented. There are two types of glucose: α-glucose and β-glucose. When α-glucose molecules bond, they form starch; when β-glucose molecules bond, they form cellulose. Therefore, α-glucose is abundant in grains we commonly eat, such as rice and wheat, while β-glucose is the main component of cellulose, which makes up plant cell walls.
Depending on the type of feedstock, bioethanol production has evolved through three major stages. First-generation bioethanol uses starch-rich crops such as sugarcane, corn, potatoes, and sweet potatoes as feedstock. While it offers the advantages of a relatively simple manufacturing process and high productivity, it can lead to problems such as rising food prices and a shortage of arable land because food resources are diverted to fuel production.
To address these issues, second-generation bioethanol utilizes lignocellulosic biomass, such as waste wood and agricultural byproducts. While it has the advantage of not using food resources, it has the limitation that the process of breaking down cellulose into glucose is complex and requires significant time and cost.
Third-generation bioethanol uses red algae, including the seaweed E UndariaE , as a feedstock. Since red algae are not major food resources, they can help alleviate food shortages; furthermore, they contain polysaccharides, which are relatively easier to break down than cellulose, offering high potential for improving production efficiency. For these reasons, algae-based bioethanol is being actively researched as one of the next-generation biofuel technologies. However, the level of commercialization and economic viability vary depending on the country and technological capabilities, and ongoing research and development is currently underway.
How is bioethanol produced?
After starch or cellulose is broken down into glucose, the glucose undergoes a fermentation process. A key concept here is alcoholic fermentation. In an environment with sufficient oxygen, yeast completely breaks down glucose to produce carbon dioxide and water; however, in an oxygen-deficient environment, it cannot fully break down the glucose and instead produces ethanol along with carbon dioxide. This process is called alcoholic fermentation.
After fermentation is complete, fractional distillation is performed to increase the concentration of ethanol. This process takes advantage of the fact that ethanol has a lower boiling point than water. When the temperature of the mixture is gradually raised, the ethanol vaporizes first; by cooling and recovering this vapor, a solution with a high concentration of ethanol can be obtained.
Currently, bioethanol is mostly used as an automotive fuel by blending it with gasoline in a specific ratio, rather than in its pure form. Since bioethanol releases the carbon that plants absorbed during their growth, it is expected to reduce greenhouse gas emissions compared to fossil fuels and can also reduce emissions of certain air pollutants, such as sulfur oxides. Furthermore, because it uses renewable biomass as a feedstock, it is regarded as a sustainable energy source.
Current Status of Bioethanol Use Worldwide and in South Korea
Recently, as energy security concerns and carbon-neutral policies have gained traction, many countries have been actively utilizing biofuels, including bioethanol. The United States, the world’s largest producer of bioethanol, primarily produces bioethanol from corn and widely uses fuel blended with gasoline. Brazil is a leading producer of bioethanol using sugarcane as its primary feedstock and has long fostered the related industry through government policy support. Currently, flex-fuel vehicles are widely available, allowing drivers to freely choose between gasoline and ethanol or use a blend of the two. Furthermore, several other countries with climates suitable for sugarcane cultivation are also utilizing bioethanol as an important renewable energy resource.
Research related to bioethanol is also ongoing in South Korea. In particular, bioethanol production technology using seaweed is one of the areas that South Korean researchers have been steadily exploring. Research on fermentation technology using red algae and improvements to the production process has been conducted, and based on this, demonstration studies on seaweed-based bioethanol have also been carried out. This research is significant in that it presents the possibility of utilizing various types of biomass in South Korea, where lignocellulosic biomass is relatively scarce. However, due to issues such as economic viability and production costs, efforts have so far focused on technology development and demonstration studies rather than large-scale commercialization.
Bioethanol is one of the leading renewable energy sources capable of reducing fossil fuel use and cutting greenhouse gas emissions. Of course, challenges such as securing raw materials, production costs, and economic viability still remain to be addressed. Nevertheless, if continuous technological development and improvements in production processes are achieved, bioethanol can play a significant role in increasing the diversity of energy resources and strengthening energy security. South Korea, too, needs to steadily expand its research and industrial competitiveness in various biofuel technologies, including bioethanol, to reduce its dependence on foreign energy and establish a sustainable energy system.
