Revisiting Coal: Japan's Technologies Offer an Alternative Path to Decarbonization

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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.

Continue reading the full story on Japan 2 Earth to read more about technologies being developed to decarbonize coal-fired power.

And find more great articles on the environment and the challenges of achieving the SDGs on our affiliated website Japan 2 Earth (J2E), sparking a transition to a sustainable future.

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(Read the article in Japanese.)

Author: Shunichi Takahashi