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Discussions are ongoing to revise Japan's Basic Energy Plan, which serves as a guideline for medium to long-term energy policy. Balancing decarbonization with energy security is a challenge. As such, a major focus has been placed on nuclear power and renewable energy, neither of which emit CO2 during generation. However, thermal power generation – including coal – should not be overlooked. It provides roughly 70% of Japan's power supply.
A Long-Term Plan for Coal
Thermal power generation involves burning fossil fuels to produce electricity. Accordingly, CO2 is emitted. Emissions for coal, in particular, are high. Even with Japan's state-of-the-art technology, they are about twice the emissions of liquefied natural gas (LNG). Meanwhile, the international community is increasingly tough on coal.
The G7 Ministers' Meeting on Climate, Energy, and Environment Ministers' Meeting in April 2024 released a statement explicitly agreeing to phase out unabated coal power plants by 2035.
However, coal is cheaper than other energy resources and can be supplied stably over the long term. Most coal-producing nations are politically stable.
For Japan, which relies heavily on imported energy resources, coal is indispensable from both the economic and energy security perspective. Thus, we need to quickly establish decarbonization technology for coal power to pave the way for its use over the medium and long term.
Ammonia Co-Firing
Co-firing is one promising technology. It involves mixing ammonia, which does not emit CO2 when burned, with coal. If established, co-firing could reduce CO2 emissions while utilizing existing facilities.
In April 2024, JERA, Japan's largest thermal power generation company, tested co-firing technology at Unit 4 of its Hekinan Power Station in Aichi Prefecture. The test substituted ammonia for 20% of the fuel. But when combustion is poor, ammonia can produce polluting nitrogen oxides (NOx). Thus, the test aimed to verify stable combustion that suppressed NOx emissions.
The key lies in IHI's combustion technology, which allows for millisecond-level control of the injection of coal and ammonia. This creates an area within the combustion chamber for ammonia to burn cleanly.
The tests ended in late June and confirmed that NOx emissions were equal to or less than burning coal alone. Moreover, the reduction in coal resulted in decreased emissions of CO2 and sulfur oxides (SOx). Shinichi Takano, Director at IHI, commented, "We experienced no significant challenges in performing ammonia co-firing."
According to JERA President Hisahide Okuda, the company plans to begin commercial operation at 20% ammonia co-firing in 2027 and expand across Japan from there. By the 2040s, they aim to fully convert to generating power with 100% ammonia.
Carbon Capture and Storage
Meanwhile, J-Power is taking a different approach to decarbonizing coal. The company has been working to demonstrate integrated gasification combined cycle (IGCC). This technology turns coal into gas to extract hydrogen and other gases, generating power with both gas and steam turbines. The company has successfully captured more than 90% of the CO2 produced during gasification.
IGCC technology will be introduced at the Matsushima Thermal Power Station in Nagasaki Prefecture, a facility that has been operating for over 40 years. Unit 1 will be decommissioned by the end of March 2025, and operation of Unit 2 will be suspended. Then starting in 2026, Unit 2 will undergo modifications to install coal gasification equipment. The company aims to restart operations in 2028.
The company will establish carbon capture and storage (CCS) technology to store captured CO2 underground.
"We plan to generate power by extracting hydrogen domestically from imported fossil fuels and disposing of the resulting CO2 through CCS. this method has the highest feasibility," commented Hideaki Kato, Director at J-Power.
Challenges Ahead
Technological challenges remain for the decarbonization of coal-fired power. Securing large amounts of ammonia is one of them. Criticism from Western countries who view the efforts as a strategy to extend the life of coal power will also be faced. However, energy security considerations require Japan to retain multiple options. Moreover, advancing the development of decarbonization technologies holds great significance.
The benefits do not stop there. These technologies could also contribute to the decarbonization in Southeast Asia, where coal-fired power is needed to meet growing electricity demand alongside economic development. IHI has reportedly received inquiries about ammonia co-firing technology from many Asian countries, including India and Malaysia.
Ken Koyama, Senior Managing Director and Chief Economist at the Institute of Energy Economics, Japan, explained.
"Japan paving a path to reducing CO2 while using coal would have major implications for decarbonization on a global scale," he said.
Japan has long asserted that there is no one path to decarbonization. The successful application of decarbonization technology for coal-fired power will demonstrate the veracity of this argument to the world.
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