KR Webzine Vol.151

1. Expansion of renewable energy

The United Nations Climate Change Conference COP 21 in 2015 sought to address the challenge of global warming due to increasing greenhouse gas emissions.  As a result, measures to reduce carbon dioxide have become increasingly important and investment in renewable energy is growing as it offers a fundamental way to reduce greenhouse gas emissions. At the same time, various interests and investments related to renewable energy, including solar and wind power, are exploding in Korea, thanks to the government's "Plan for Implementing 3020 Renewable Energy" and the public's great interest in the environment.

2. Limits of renewable energy

External factors such as weather and wind can significantly increase the proportion of renewable energy available, but such sources are very variable and can increase the instability of the power system. For example, if you look at the situation on Jeju Island, the electricity consumed consists of base load power (45%), land power transmitted to 1 and 2 submarine cables (40%), and renewable energy (15%). However, because the base load power generation (thermal power) cannot be stopped when the power supply is expected to exceed power consumption, the power output of wind power generation mainly contributes to the grid stability. In recent years, the number of wind power output limits on Jeju Island has been on the rise. It has been surging to three in 2015, six in 2016, 14 in 2017, 15 in 2018, 45 in 2019 and 46 in July 2020. Jeju Island is expected to have an annual power limit of 20 percent of its total power generation capacity, which is the same as Ireland, an island country in Europe. 

China and Europe, which are advanced in using wind power generation, have already experienced limitations and have incurred considerable losses because of the restrictions of renewable energy output. As of 2016, in China, losses incurred by power restrictions on solar and wind power generation amounted to 20.5 billion yuan and 3.5 trillion won in Korean currency. Britain and Germany, which are most advanced in wind power in Europe, are also believed to be suffering similar losses to China as they face the same issues. 

As a result, to prepare for fluctuations in the output of renewable energy, electricity can be stored by producing renewable energy in the form of hydrogen to maintain grid stability, respond to excess electricity, and to efficiently store and use renewable energy. Various studies and trials such as P2G (Power to Gas) systems are currently underway. Korea has a growing demand for renewable energy and any hybrid systems that might be suitable for its unique environment. Hydrogen-based hybrid systems are proposed as a potential alternative. 

Hydrogen, which is clean energy, has been identified as a next-generation energy source due to its high energy density, its various uses including power generation and as a transport fuel, and it is also seen as the optimal clean energy source that can respond most efficiently to climate change. However, the domestic technology level is still not mature, and more work is needed for the development and commercialization of original core technologies. With the increase of renewable energy sources in accordance with government policy, the reality is that technology is needed to prevent load stability degradation of power, to overcome the storage capacity limits of electrical energy, and to utilize unused power. To this end, P2G (Power to Gas) technology, which can serve as a major energy source for energy mix grids, is attracting attention by converting surplus electric power into hydrogen and using it as a fuel for cogeneration and transportation of vehicles and ships.

3. P2G (Power to Gas) system

The CO2-free hydrogen reproductive system which does not emit any greenhouse gases at the pre-process level of hydrogen production, is the only hydrogen production method that uses electricity from renewable energy generation the hydrogen produced is called green hydrogen. The water electrolysis method uses technology that dissolves water into hydrogen and oxygen by supplying electricity to electrolytes used for ionization of water. Depending on the type of electrolysis, it is divided into alkaline electrolysis (Alkaline), or polymer electrolyte membrane water electrolysis (PEM), or the Solid Electrolysis Cell (SOEC) method. Alkaline electrolysis is currently most commercially used method today.

Alkaline water electrolysis is currently the most advanced in commercialization among water electrolysis technologies. The electrolysis of water is achieved using mainly alkali electrolyte, as a result of the electrical reactions occurring at each electrode of a unit cell. In terms of maturity of technology, the alkaline water electrolysis method has been researched and developed for a long time and has now been commercialized and is being marketed in Korea.

Polymeric electrolytic membrane (PEM) hydrolysis is a technology that electrically decomposes water using an ion conductive polymer electrolyte membrane (PEM) as electrolyte and is based on the electrical reaction that occurs at each electrode of a unit cell. This polymer electrolytic membrane water electrolysis method is known to be the best of the three methods in terms of system miniaturization, maintenance and repair. Unlike alkaline water electrolyte technology, polymeric electrolyte water electrolysis technology is still in the empirical stage in Korea, but some companies have succeeded in commercializing it and are selling products overseas. 

Solid Oxide Electrolyzer Cell (SOEC) or hot water vapor electrolysis is a technology that generates hydrogen by electrolyzing hot water vapor above 800°C using solid oxide electrolyte.  It uses the smallest amount of power compared to other water electrolysis technologies, but requires separate heating to maintain a high temperature. Although solid oxide hydroelectricity is inferior to other hydroelectric methods in terms of maintenance and durability because all materials are ceramic materials, the hydrogen production costs are expected to be the lowest in terms of energy efficiency, making it possible to achieve mainstream water electrolysis technology in the future.

4. A Study on Power to Gas (P2G) in KR

The KR Research Center is the only domestic institution that operates the Korea Accreditation System (KAS) system for wind power generation. The government is operating a 'Wind Turbine KS Certification' system for 11 private power generation companies, which is part of the Renewable Portfolio Standard (RPS).  KR has been designated as a design and evaluation agency for wind  power generation systems and is acting as a pivotal institution, issuing the Renewable Energy Certificate (REC). 

In addition to these tasks, KR is conducting considerable research into P2G, using renewable energy. KR recently won a government R&D contract entitled "Development of 2 MW Power-to-Gas System Engineering Technology and Business Model (Director: Kang Moon-jong)", which is a project to maximize the use of renewable energy.  KR has been working with KEPCO, Korea East-West Power, Korea Midland Power, Doosan Heavy Industries and Doosan Heavy Industries & Construction, and Korea Advanced Institute of Technology for three years in this area. Separately, research on P2G-related demonstration is being carried out in cooperation with leading conglomerates related to hydrogen energy and is expected to be fruitful soon.

Based on the technologies and experiences accumulated through these various research activities, KR’s  research headquarters will establish a Certificate of Green Hydrogen (CertifHy Guarantee of Origin(GO)) and in the longer term will link it with the hydrogen certification system-linked fuel cell REC weight adjustment for power generation, to generate additional profits. 

In addition, the government is pushing for the development of a hydrogen fuel cell ship that applies a hydrogen fuel cell power generation system to small vessels, and also aims to reduce ship emission pollutants by utilizing green hydrogen produced.  Once established, KR will also provide a certification system that performs verification of all these processes .

5. Conclusion

Renewable energy, hydrogen, ship... … a combination of words that would not usually go together, are all connecting under the influence of the government's “Green New Deal” and its core “Hydrogen Economy Revitalization Roadmap”. Along with the energy policy aspect, this is centered on the policy of fostering high-tech industries, which is part of the government's innovative growth policy, and the hydrogen economy is considered to be economically valuable and important. In addition, it is clear that the justification for implementing the hydrogen economy is not only of economic value, but also environmental, as it offers an effective way to reduce greenhouse gas emissions and to reduce fine dust due to de-carbonation of energy consumption through hydrogen utilization.

In order to preempt changes in technology trends, the research center continues to investigate various projects related to hydrogen, and one of them will focus on producing hydrogen using renewable energy, and P2G. With the hydrogen produced by renewable energy expected to be used as fuel for ships quite soon, preliminary responses to hydrogen-related rules and technologies are being prepared in various fields within the research headquarters.