In this blog post, we will examine the potential and limitations of bioenergy and consider its role as a sustainable energy source.
Modern industrial civilization has its roots in the Industrial Revolution of the 19th century. One of the driving forces behind the Industrial Revolution was the use of fossil fuels. During the First Industrial Revolution, fossil fuels were simply used as fuel to heat steam engines, but with the widespread use of internal combustion engines around the time of the Second Industrial Revolution, the importance of fossil fuels increased even more. Later, as electricity became widely used in industry and spread to households, fossil fuels were also used to generate electrical energy. In the 20th century, fossil fuels began to be used to manufacture various organic compounds and plastics. Today, we live in the age of oil and coal.
However, the problems with an industrial structure so dependent on fossil fuels became apparent before the end of the 20th century. Direct environmental pollution occurred, including limited reserves of fossil fuels, air pollution caused by carbon dioxide, sulfur oxides, and nitrogen oxides from the use of fossil fuels, and marine pollution caused by oil spills. In addition, the scale of additional damage caused by global warming and global climate change due to increased carbon dioxide concentrations is difficult to estimate.
Therefore, in order to reduce the use of fossil fuels, governments and international organizations such as the United Nations have been working to develop various alternative energy sources to curb carbon emissions. As a result, alternative energy sources such as solar and solar thermal energy, hydroelectric energy, wind energy, tidal energy, geothermal energy, nuclear energy, and hydrogen energy have been developed, most of which emit very little carbon.
However, these alternative energy sources have a fundamental problem in that they cannot be used as fuel for internal combustion engines. In addition, most alternative energy sources are difficult to store and produce little energy compared to the investment costs and power generation time required. Bioenergy, such as bioethanol and biodiesel, has emerged as a new energy source that solves these problems of alternative energy sources.
Bioenergy is an alternative energy source that obtains hydrogen and organic carbon by decomposing biomass, which refers to organic carbon sources such as wood, agricultural crops, and food waste. In this process, various hydrocarbons, biodiesel, methane, ethanol, and other substances can be obtained. The key point of bioenergy is that the amount of carbon dioxide generated when energy is used is zero or negative. In particular, when plant products are used, the carbon dioxide fixed during photosynthesis is simply re-emitted, so carbon dioxide emissions are zero. The same is true for hydrogen and methane obtained by decomposing organic waste. Therefore, bioenergy is a fuel that can power internal combustion engines, and carbon emissions are ultimately zero. This means that it has all the advantages of existing alternative energy sources and fossil fuels.
However, does bioenergy really have a bright future? Are bioenergy carbon dioxide emissions zero? Various academic papers have emphasized the importance of the bioenergy industry and highlighted its advantages. However, bioenergy has fundamental problems. Bioenergy is still organic energy based on a carbon skeleton, so it emits carbon dioxide when burned. An even more important issue is the reality of the bioenergy production process.
In order to obtain bioenergy, especially biodiesel and bioethanol used for transportation, it is necessary to ferment edible crops. The United States and Brazil, the world’s largest and second largest producers of bioethanol, grow corn and sugarcane in large quantities for fuel. Fossil fuels or bioenergy are needed to harvest raw crops and transport them to bioenergy production plants. The harvesting and fermentation of corn and sugarcane inevitably emit carbon dioxide. Sugarcane, the raw material for bioethanol in Brazil, is harvested using traditional methods, which involve burning unnecessary leaves and stems, releasing large amounts of carbon dioxide. Bioethanol fermented from corn in the United States requires the extraction of sugar, which inevitably incurs additional costs and carbon dioxide emissions. Therefore, carbon dioxide emissions are unavoidable during transportation and production. In addition, in order to meet the current demand for fossil fuels, crops such as corn must be grown on astronomically large areas of land for fuel. Growing these fuel crops requires not only the expansion of farmland but also the use of large amounts of fertilizer and water, which are also major causes of environmental pollution.
In addition, biodiesel and bioethanol are obtained from food crops. Typical crops for bioethanol include sugarcane in Brazil and corn in the United States, while biodiesel is obtained from rapeseed, soybeans, sunflowers, palm oil, and other sources. Corn, in particular, is a staple grain widely used alongside wheat and rice, while sugarcane is a crop that produces sugar, an important food resource. When large amounts of food crops are used to produce bioenergy, there will be a corresponding shortage of crops that can be used as food. These food crops are important food resources that are mainly imported by third world countries. Therefore, when multinational energy companies purchase these crops in large quantities to produce bioenergy, countries that need food will experience food shortages. Furthermore, according to the law of supply and demand, there is a limit to how much supply can increase, so if demand continues to rise, supply prices will rise. Therefore, mass production of bioenergy can lead to price increases for various food crops.
The impact of bioenergy on tropical deforestation is greater than imagined. Corn, sugarcane, and oil palm, which are representative bioenergy crops, thrive in tropical climates. In addition to the United States, the largest producer of corn for fuel, and Brazil, the largest producer of sugarcane, palm oil, a raw material for biodiesel, is produced in Indonesia and Malaysia. In Indonesia, in particular, a significant area of tropical rainforest and wetlands is being cleared for the cultivation of oil palm trees for palm oil production, and uncontrolled burning of unprofitable stumps causes damage to the surrounding rainforest. Furthermore, if various countries in Africa, which have the potential to become bioenergy producers, jump into the bioenergy industry in earnest, the tropical rainforests of Central Africa, which are suitable for growing bioenergy crops, will be greatly damaged. This will not only disrupt the carbon cycle and increase carbon dioxide emissions, but also destroy the biodiversity of the endangered rainforests. Turning a blind eye to the deforestation of tropical rainforests for the sake of bioenergy is an act that is blind to immediate profits and fails to address future losses, and is essentially no different from the current indiscriminate use of fossil fuels.
Of course, since bioenergy production using food crops and wood has the above problems, methods for producing more carbon-neutral bioenergy have been devised. Typical examples include obtaining methane and hydrogen from organic waste, and obtaining ethanol and various hydrocarbon gases from industrial by-products such as waste paper and rice straw, as well as agricultural by-products. In the former case, it is positive in that it reduces environmental pollution caused by direct dumping, landfilling, or incineration of waste, and that it becomes a useful fuel rather than being decomposed into unusable carbon dioxide. In addition, methods using methanol and bioethanol extracted from wood are also being actively researched. Bioethanol extracted from wood biomass is not only more economical than bioethanol extracted from corn, but also reduces carbon dioxide emissions by 40% and has better fuel quality. However, these alternatives also have some fundamental limitations. It is very difficult to secure a supply that can replace fossil fuels. Wood bioethanol also has the potential to conflict with existing wood-using industries, as it requires the use of wood, which is a limited resource. Furthermore, wood grows and matures more slowly than annual crops, and its generation replacement cycle is also slow.
Recognizing these problems, the focus of bioenergy production has recently shifted from land to the sea. The sea accounts for about 71% of the Earth’s surface, and photosynthetic algae living in the sea account for about 90% of the Earth’s total carbon fixation. South Korea is surrounded by the sea on three sides and is one of the world’s three largest seafood producers, along with Japan and China. Therefore, by expanding existing seaweed farms and cultivating algae for bioenergy on a large scale, it will be possible to obtain more bioenergy than from crops in an economically viable manner. However, this is still in the preliminary stages of commercialization, and technical limitations and process inefficiencies must be improved.
Of course, it would not be wise to halt the development and production of bioenergy simply because it has the limitations mentioned above. Fossil fuels are rapidly being depleted, and there is currently no clear alternative to replace them. Hydrogen energy systems, which are rapidly emerging as an alternative to bioenergy, are also currently heavily dependent on the petrochemical industry. Furthermore, even if carbon-neutral electric vehicles, hydrogen-oxygen fuel cells, and nuclear fusion power generation, which greatly reduces the use of fossil fuels, become practical, fossil fuels and bioenergy will continue to be used. This is because hydrocarbons are essential for the production of petrochemical products, namely plastics, which sustain human life. Therefore, the bioenergy industry for the production of fuels and petrochemical products is essential for sustainable development.
Some of the environmental concerns raised about the bioenergy industry are exaggerated. In the United States and Brazil, the world’s largest producers of bioethanol, the cultivation of bioenergy crops is not linked to deforestation. Sugarcane grown in Brazil is cultivated in the central and southern regions, far from tropical rainforests such as the Amazon, on existing wasteland or land that has already been cleared. The same is true for the bioenergy industry using microalgae. These industries adopt a method of collectively cultivating and harvesting microalgae in coastal aquaculture farms, so they do not have a negative impact on the marine ecosystem. Although bioenergy is not entirely environmentally friendly, its development does not necessarily lead to indiscriminate destruction of the environment. The rise in corn prices caused by bioethanol production is also exaggerated. The increase in corn prices due to the increase in corn cultivation for fuel is not expected to be significant, at around $3.6 per bushel, which is only a 50% increase compared to prices before 2008, and corn consumption and supply are expected to remain in balance.
However, we must clearly recognize the fundamental limitations of bioenergy and avoid overproduction that could adversely affect the ecosystem and global food resources. Instead, bioenergy should be used as an intermediate step until carbon-neutral, sustainable, and highly efficient energy resources such as nuclear fusion energy and hydrogen energy are commercialized in the fuel sector. For the production of synthetic resins such as plastics and synthetic fibers, continuous research is needed to minimize the environmental impact and technological innovation is necessary to enable efficient bioenergy production even in small areas. South Korea is currently lagging behind in the development of the bioenergy industry, which is highly competitive in countries such as the United States, Brazil, Malaysia, and Indonesia. In the future, when oil becomes scarce, this situation could once again lead to energy dependence, so it is necessary to develop a national bioenergy industry. However, scientists and engineers must clearly recognize the limitations of bioenergy and mention not only its advantages but also its disadvantages so that the public does not blindly believe that bioenergy is a clean energy source.
The bioenergy industry needs continuous development, and even if humanity stops using fossil fuels, the use of bioenergy will continue. Bioethanol and biodiesel, which are currently the main forms of bioenergy, have a direct impact on environmental destruction, such as deforestation, increased demand for food crops, and expansion of agricultural land. Therefore, it is necessary to develop and commercialize bioenergy that is free from such constraints as much as possible. South Korea, which currently imports an absolute majority of its fossil fuels from overseas, must increase its energy independence through the development of bioenergy. To this end, scientists and engineers must clearly recognize the limitations of existing bioenergy technologies and strive to develop bioenergy that is more environmentally friendly and independent of food resources.
