[Public Voices] Ammonia Co-Firing Power Generation: A Stepping Stone Toward a Clean Hydrogen Society

Contributing to Fine Dust Reduction by Replacing Coal
Complete Removal of Ammonia Through Environmental Equipment

Professor Ryu Chang-guk, Department of Mechanical Engineering, Sungkyunkwan University

Following the pilot project for the clean hydrogen certification system in March this year, the world's first clean hydrogen power generation bidding market was launched in May, gradually establishing an institutional framework for the transition to a clean hydrogen ecosystem.

Ammonia co-firing power generation involves converting clean hydrogen into ammonia and then co-firing it with coal-fired power plants. It is one of the core policies of clean hydrogen power generation. Ammonia co-firing power generation is expected to serve as a stepping stone toward a hydrogen society by ultimately reducing fossil fuel use and greenhouse gas emissions.

However, recently, environmental groups both domestically and internationally have expressed concerns about ammonia co-firing power generation. One concern is that ammonia co-firing could be used as a means to extend the lifespan of coal-fired power plants. Since the levelized cost of electricity (LCOE, KRW/kWh), which refers to the cost required to produce electricity, needs to be lowered by extending the operation period, some view ammonia co-firing as a loophole to prolong the life of coal-fired power plants.

Ammonia Co-firing Power Generation Configuration Diagram

However, the current contract period for the clean hydrogen power generation bidding market is limited to 15 years, with an additional condition that it cannot exceed the remaining lifespan of the existing plant. Therefore, it is only possible to expect a reduction in carbon emissions during the remaining lifespan, making any trick to extend the life of coal-fired plants fundamentally impossible.

Additionally, power plants participating in the bidding are evaluated on non-price factors such as environmental contribution, industrial and economic contribution, project reliability, community acceptance, project progress, and grid compatibility. Coal-fired power plants equipped with relatively high-efficiency eco-friendly functions tend to receive favorable evaluations. Power generation companies operating the latest 1-gigawatt (GW) class plants in Korea will become the most advantageous power producers if they develop and operate appropriate clean fuel supply models.

There are also concerns about ammonia slip, where incompletely combusted ammonia is emitted. However, ammonia co-firing power generation removes ammonia through boilers as tall as 30-story apartment buildings and a five-stage environmental facility process.

The coal and ammonia supplied to the boiler burners undergo sufficient residence time in a high-temperature zone (1200?1500 degrees Celsius) at a height of 70?80 meters, achieving almost complete combustion. Experiments conducted by domestic research institutes such as the Korea Institute of Machinery and Materials and the Korea Electric Power Research Institute have confirmed complete combustion of ammonia even under unfavorable conditions like lower temperatures compared to actual boilers.

If a small amount of unburned ammonia remains due to design or operational defects, it is removed through denitrification facilities that eliminate nitrogen. Any remaining ammonia is then almost completely removed through processes such as electric precipitators and lime slurry showering. Finally, any ammonia that might still exist is removed in the fifth stage, the mist eliminator.

Ammonia slip is not a technical concern. More importantly, nitrogen oxides (NOx) generated during the ammonia combustion process need to be addressed. To this end, optimizing the combustion method is necessary, and with currently developing technologies, it is expected that emissions can be easily maintained at levels equal to or below those of coal combustion.

The ammonia co-firing policy in coal-fired power plants is one of the best measures for large-scale greenhouse gas reduction in the power sector and the expansion of the hydrogen ecosystem in Korea's current context. Moreover, by replacing coal, ammonia co-firing is expected to reduce emissions of sulfur oxides and particulate matter, thereby contributing to the reduction of fine dust.

Ryu Chang-guk, Head of the Department of Mechanical Engineering, Sungkyunkwan University (Vice President of the Korean Combustion Society)

This content was produced with the assistance of AI translation services.