In this blog post, we will explore how energy storage technology is evolving to support a sustainable future, as well as its importance and potential applications.
Energy refers to the ability to perform work and is utilized in various forms in our daily lives. Examples include electrical energy to power smartphones, chemical energy to propel cars, and thermal energy to generate electricity. Energy is an essential element of human life and an indispensable resource in modern society. The energy we use not only makes our lives more convenient but also has a direct impact on the economy, industry, and the environment. Therefore, using energy efficiently has a significant impact not only on individual lives but also on the future of nations and the entire planet.
However, since resources for energy production are limited, we need to use energy efficiently and conserve it. Energy conservation must be approached not merely as a matter of reducing costs, but from the perspective of protecting resources and preserving the environment. Furthermore, due to the nature of power generation facilities—which supply a certain amount of energy until the end of their operational life once they are activated—imbalances between supply and demand can occur. For example, energy shortages occur during the daytime when energy consumption is high, while the opposite happens at night when there is a surplus of energy. To solve this problem, energy storage technology—which allows us to save energy when there is a surplus and borrow it when there is a shortage, much like depositing and withdrawing money from a bank—is essential. Such technology plays a crucial role in designing a more sustainable future.
Energy storage methods can be categorized by principle into mechanical, electrical, thermal, biological, and chemical storage. Each storage method can be compared in terms of energy conversion efficiency and energy density. Energy conversion efficiency refers to the proportion of stored energy that can actually be utilized, while energy density indicates the amount of energy produced per unit weight or volume. These two factors are key criteria for evaluating the efficiency of energy storage methods. For example, a storage method with high energy conversion efficiency can minimize energy loss, while high energy density allows for storing more energy in a smaller space.
Mechanical storage converts excess energy into mechanical energy for storage. Typical examples include pumped-storage dams and compressed air storage. Pumped-storage hydroelectric dams store energy during periods of low energy consumption by releasing excess water from hydroelectric dams. This method involves pumping the released water back up to a higher elevation and then using it for power generation during periods of high demand. Although this method has low energy density, it is capable of storing large amounts of energy and has already been commercialized and is widely used. Compressed air energy storage involves compressing gas to reduce its volume for storage, then releasing the stored gas through a narrow opening when needed to drive a turbine and generate electricity using the pressure. Simply put, you can think of it as inflating a balloon to store energy when there is a surplus, and then using the compressed air when needed. This method primarily involves creating underground cavities to store air, which requires technology to maintain airtightness to prevent leaks, and has the drawback of emitting significant pollutants during the cavity creation process.
Thermal storage involves using surplus energy to heat an object and then reusing the stored thermal energy when needed. For example, when installing thermal storage walls for winter heating, the storage material absorbs excess solar energy during the day, and releases heat after sunset when temperatures drop, providing heating. Using a similar principle, water tanks can store solar energy during the day due to water’s high specific heat capacity, which can then be used for heating at night.
A drawback of thermal storage methods is that it is difficult to convert the stored heat into other forms of energy. In other words, energy stored through thermal storage cannot be converted into electrical energy for use; it can only be utilized in the form of heat. However, thermal storage methods can significantly improve the heating and cooling efficiency of buildings, playing a crucial role in sustainable architectural design.
Electrical storage involves charging excess electrical energy into lead-acid or lithium batteries for later use when needed. This method is most commonly used for small-scale power supply rather than large-scale power supply. A prime example is the battery in portable electronic devices. The drawbacks of this method include the ease of discharge and the difficulty of storing large amounts of electricity. However, through continuous technological development and innovation, the efficiency of electrical storage methods is gradually improving, and it is expected that more applications will become possible through integration with renewable energy. The largest operational electrical storage system currently in use is located in Fairbanks, Alaska, USA. This system can supply 26 MW of electricity for 15 minutes and 40 MW for 7 minutes to prepare for emergencies such as power outages.
Biological storage is a method of storing energy using plants; simply put, it involves growing plants. Plants store solar energy through photosynthesis, and this stored energy can be used when needed. The process of drying plants grown in this way and burning them to generate energy is called biomass, while the use of sugars stored in plants as a substitute for fossil fuels through chemical processes is called biofuel. While these biological storage methods are receiving significant attention for their environmental friendliness, they have the drawback of making it difficult to artificially adjust energy levels in the short term. Furthermore, the resources, time, and environmental impact required during the production of biomass and biofuels must be considered, and more research and improvements are needed to ensure true sustainability.
The most well-known method of chemical storage is hydrogen. This involves generating hydrogen through methods such as water electrolysis or thermal decomposition when energy is in surplus, storing it, and then using it later. The hydrogen produced in this way is widely used as an energy source for fuel cells. However, compared to natural gas (methane), which is currently widely used, hydrogen has a lower energy density, meaning that large quantities must be used. Furthermore, hydrogen’s low energy density implies that significant technological development is required for its storage and transportation. Nevertheless, hydrogen is likely to play a crucial role in future energy systems as an eco-friendly energy source, and related research and investment continue.
We have examined various energy storage methods so far. Humans must use energy to survive, and since the energy we obtain comes from limited resources, we must use it wisely. However, it is difficult to produce large-scale energy immediately to meet our demands. Therefore, energy storage technology is essential, as it allows us to balance energy supply and demand. Furthermore, various energy storage technologies are currently being developed and researched, and as these technologies advance, we will be able to build a more sustainable energy system. Research and investment in energy storage technology must continue in the future, and this will be a critical task for our future.
