【Report】 Limited decarbonization impact of power generation from hydrogen/ammonia co-firing – Kyoto University

Researchers from Kyoto University have published an article in the March 4, 2024 edition of the international journal Nature Communication, emphasizing the limited impact on decarbonization of power generation from hydrogen/ammonia co-firing.

Assistant Professor Ken Oshiro and Professor Shinichiro Fujimori, both members of the Division of Environmental Engineering in Kyoto University’s Graduate School of Engineering, used a global energy simulation model and analyzed the role of hydrogen/ammonia on power generation toward decarbonization. Although it is expected that the use of hydrogen/ammonia made from renewable energy for power generation may contribute to reducing emissions from thermal power generation, its operation time will be restricted to the time when the output of solar and wind power generation is reduced.

Therefore, the results indicate that the impact of hydrogen/ammonia co-firing on fossil-based power generation is limited, as the electricity supply from co-firing is limited to about 1% of total electricity generation.

The Japanese government and major electric power companies are investing huge sums of money to promote the use of hydrogen/ammonia produced from any source – not just low-carbon hydrogen – as a path to decarbonization. Additionally, the government aims to expand this strategy to other Asian countries. However, throughout the world hydrogen/ammonia is generally considered for use in fields where there are no other alternatives.

In this study, researchers used the Asia-Pacific Integrated Model (AIM) model to estimate CO2 emissions, energy supply and demand, and the amount and cost of energy technology deployment using input conditions such as future population, economic growth, and technological progress (efficiency, cost, etc.). Simulations were conducted under various conditions, including cases where the cost of hydrogen and ammonia decreases significantly.

Results of the simulation are as follows:

  • If the global targets of limited the earth’s warming to 2℃ or 1.5℃ are to be achieved, the amount of power generated by thermal power generation must decline, even under conditions where hydrogen prices drop significantly, with hydrogen and ammonia dedicated and co-fired generation accounting for only about 1% of global electricity generation at most.
  • In the scenario with significantly lower hydrogen prices, it was shown that about half of the world’s thermal power generation capacity could be equipped with hydrogen co-firing facilities, but these facilities would only be in operation for a very short period of time when the output of renewable energy (solar and wind) is significantly lower.
  • As the co-firing ratio of hydrogen/ammonia increases, the costs of CO2 emissions associated with the carbon pricing on coal and gas decreases, but the costs of fuels associated with procuring hydrogen/ammonia increase. So, the overall cost advantage is very small.

As a replacement for fossil fuel, co- or mono-firing of hydrogen/ammonia can be an option for reducing CO2 emissions if that hydrogen/ammonia is produced using electricity generated from renewable energy. It is also possible to use hydrogen for variable renewable energy (VRE) adjustment (as a power storage option). However, although the cost of solar and wind power generation continues to decrease, the supply of low-carbon hydrogen produced by electrolysis from renewable energy is expected to increase.

Furthermore, while hydrogen co-firing may still be utilized in certain scenarios, the amount of electricity generated by fossil fuel-fired power plants, including hydrogen co-firing, is expected to decline rapidly as fossil fuels are phased out in the power sector. In this regard, the amount of electricity generated by hydrogen co-firing is expected to be only a fraction of total electricity production.

This research notes that there have been few studies evaluating the use of hydrogen in the power sector, so there are still several gaps in our knowledge of its potential role, and the potential impact of hydrogen co-firing on avoiding stranded asset risk has not yet been fully explored.

Hydrogen use in the power sector has limited impact on overall power generation

While there is still a possibility that hydrogen co-firing could be adopted in some scenarios, fossil fuel-based electricity generation declines in all of the study’s scenarios. The study concludes that the share of hydrogen co-firing in all scenarios analyzed is negligible compared to total electricity generation, and that even taking multiple scenarios into account, the share in 2050 will be less than 1%.

Even in scenarios where hydrogen co-firing with fossil fuels increases, it will be used as a backup power source to regulate VRE, and the average annual capacity factor (utilization rate of facilities) will be low: less than 30% for gas co-firing, and less than 5% for coal co-firing. In contrast, the study indicates that fossil fuel-fired power plants with CCS will have higher capacity factors than hydrogen co-firing (up to 70% for gas and up to 30% for coal) by 2050.

In every analyzed scenario, it is clear that hydrogen co-firing has a limited role in decarbonization

The study also discusses the role of hydrogen co-firing in decarbonization, noting that while hydrogen co-firing can reduce the risks of coal- and gas-fired power plants becoming stranded assets in some scenarios, it is not cost-effective. If hydrogen co-firing can replace fossil fuel generation as a backup power source, emissions can be reduced, but the impact on stranded power generation will be limited.

In addition, since hydrogen as a fuel is expensive to produce, the levelized cost of electricity (LCOE) varies depending on the scenario, but the study indicates that the LCOE of hydrogen co-firing power generation is much higher than that of power generation without co-firing. The finding remains that hydrogen co-firing is utilized only as a backup for VRE and, as a result, the contribution of hydrogen co-firing to overall power generation is limited.

The study also notes that while hydrogen and ammonia are attractive options as backup power sources for solar- and wind-based power systems, which are vulnerable to extreme conditions such as extreme weather and natural disasters, the use of hydrogen and ammonia in the power generation sector is limited, while the use of hydrogen and ammonia as aviation and transportation fuel is relatively easy to advance.

Related Links

News Release: Kyoto University Research Information Repository
Nature Communication : Limited impact of hydrogen co-firing on prolonging fossil-based power generation under low emissions scenarios, DOI 10.1038/s41467-024-46101-5

Written/Published: Nature Communications (Authors: Ken Oshiro & Shinichiro Fujimori)
Published: March 4, 2024