대학신문방송국

Hydrogen Energy

By Woo Jung-kyu Reporter, Senior of Industrial Engineering

‘Over the past 200 years, the power of fossil fuels has returned as bills that threaten the survival of mankind, which is destroying the global environment. The world’s greenhouse gas emissions, which are rapidly devastating the global environment, are 51.5 billion tons per year. About 75 percent of it has occurred in the process of generating energy. At the crossroads of survival, the transition to clean and renewable energy for humanity is no longer a matter of choice and cannot be delayed.’ Since the announcement of the United Nations Environment Program (UNEP) in 2019, the world has been paying attention to renewable energy such as solar and wind power, which provide clean energy from nature. However, renewable energy generated by natural forces has a limitation, as it is difficult to balance the supply and demand of energy because of irregular weather conditions. The solution to an imbalance between supply and demand is the utilization of hydrogen energy, which stores surplus electrical energy.

Definition and history

Hydrogen energy is an energy source that involves separating, producing, and using hydrogen from compounds such as water and fossil fuels. Hydrogen energy can be produced through water electrolysis, and the electricity used in this process can derive from surplus renewable energy. This enables the production of clean hydrogen without any emissions during the energy generation process. Additionally, when the hydrogen produced through this process is combined with oxygen, it can generate electricity again. The existence of hydrogen was first discovered in 1766 when British scientist Henry Cavendish succeeded in isolating hydrogen gas. Seventeen years later, French physicist Jacques Charles demonstrated the potential of hydrogen energy by successfully launching the world’s first unmanned hydrogen balloon. In 1839, British physicist William Grove developed the first device that generated electricity by combining hydrogen and oxygen. However, due to low efficiency, research into hydrogen energy did not advance significantly at the time. Research into renewable hydrogen began in the early 1900s, and in 1937, a hydrogen-powered airplane was built. However, the Hindenburg disaster, which occurred the same year, prevented this widespread adoption. The Hindenburg disaster occurred on May 6, 1937, when the German airship LZ 129 Hindenburg exploded and caught fire while attempting to land in New Jersey, United States of America. The airship used hydrogen instead of helium as a lifting gas, and it showed the dangers of hydrogen, leading to a sharp decline in trust in hydrogen-powered aircraft and airship. Despite its past, The first significant use of hydrogen energy came in the 1950s when NASA used this as rocket fuel and in fuel cells for space missions. Since then, hydrogen began to be recognized as a potential clean energy source, especially during the 1970s oil crisis when interest in alternative energy sources increased. Since the 1990s, growing concerns with environmental issues have led to more intensive research on hydrogen energy and fuel cell technology. Many automobile manufacturers started developing hydrogen fuel cell vehicles, and the technology began to be applied across various industries.

Production Methods and Characteristics

Hydrogen energy is a secondary energy source, which can be produced in various ways using primary energy. The main methods for producing hydrogen include fossil fuel reforming, biomass gasification, and water electrolysis.

1) Fossil Fuel Reforming Method

The fossil fuel reforming method is the most widely used hydrogen production process, where natural gas (methane), LPG, and lignite are reacted with high-temperature steam to produce hydrogen. Specifically, natural gas and water (H2O) are reacted at high temperatures (700-1,000°C) to generate hydrogen (H2) and carbon monoxide (CO). The produced carbon monoxide then undergoes an additional reaction to convert it into carbon dioxide (CO2) and more hydrogen. This method is characterized by advancing technology and the ability to produce large amounts of hydrogen at a relatively low cost. However, a significant amount of CO2 is emitted, causing harm to the environment.

2) Biomass Gasification Method

Biomass refers to the total mass of living organisms (Bio), which forms part of an ecosystem’s cycle. Also, it includes growing plants which use sunlight, animals which consume these plants, and microorganisms which decompose the remains of plants and animals. The biomass gasification method involves reacting biomass at high temperatures with oxygen or steam to produce synthesis gas (syngas), from which hydrogen is extracted. Specifically, biomass is partially oxidized at high temperatures to generate syngas, which contains gasses such as CO, H2, CO2, and methane (CH4). Hydrogen is extracted from the syngas for storage or use. The feature of this method is that it can produce carbon-neutral hydrogen by using biomass. However, the process is complex and has relatively low energy efficiency.

3) Water Electrolysis Method

The water electrolysis method involves using electricity to split H2O into hydrogen and oxygen. Specifically, water is placed in an electrolyze, and electricity is applied to separate water molecules into H2 and oxygen (O2), with the resulting hydrogen collected for storage or use. The feature of this method is that renewable energy is used as the power source, which produces clean hydrogen without carbon emissions. However, it is less economical because it requires a large amount of electricity and leads to the use of renewable energy-based power.

Types

Depending on the production method, hydrogen is divided into gray hydrogen, blue hydrogen, green hydrogen, yellow hydrogen, and pink hydrogen.

1) Gray Hydrogen

Gray hydrogen is classified as by-product hydrogen and reformed hydrogen. By-product hydrogen is produced as a by-product of petrochemical and steel manufacturing processes, which limits the potential for increased production. Reformed hydrogen is produced by using natural gas, and has the advantage of being suitable for mass production, but generates large amounts of carbon dioxide as a by-product.

2) Blue Hydrogen

Blue hydrogen is a solution to the limitations of gray hydrogen. While the production method is the same as gray hydrogen, it is referred to as clean hydrogen because the carbon dioxide generated during the production process is captured, utilized, and stored using Carbon Capture, Utilization, and Storage (CCUS) technology. The captured carbon dioxide is permanently stored or used in materials such as cement, semiconductor gasses, and tire components. Blue hydrogen is considered the most practical alternative for expanding the hydrogen industry. 

3) Turquoise Hydrogen

Turquoise hydrogen is produced by thermally decomposing natural gas. Methane (CH₄), the primary component of natural gas, is injected into a high-temperature reactor where natural gas is separated into hydrogen and solid carbon. The by-products produced during this process can be used in various products.

4) Green Hydrogen

Green hydrogen is produced by splitting water using electricity generated from renewable sources such as solar and wind, which is regarded as clean energy since no carbon dioxide is emitted during production. However, in South Korea, there are still economic and technical challenges for large-scale production of green hydrogen due to the lack of water electrolysis facilities and limited renewable energy resources.

5) Yellow and Pink Hydrogen

In addition, yellow hydrogen refers to hydrogen produced by splitting water using electricity from the existing power grid, which is not from renewable sources. Pink hydrogen is produced by splitting water using electricity generated from nuclear power.

Hydrogen energy has great potential as an eco-friendly and limitless resource. However, there are many challenges to overcome, such as difficulties in production and storage, as well as the need for infrastructure development. HBNU also has a strong interest in hydrogen energy. This can be seen through the ‘H2 CHARGE camp’, that participants learn about the principles and applications of hydrogen energy. Also, the selection of the university for the ‘Energy Technology Sharing University’ shows HBNU’s interest in it. After reading this article, why don’t you take an interest in hydrogen energy?