In our May episode of Ammonia Project Features, Yasushi Shimano (JOGMEC) and Tomoyuki Koide (Tsubame BHB) discussed CCS-based ammonia production using enhanced gas recovery (EGR) for CCS, as well as Tsubame’s alternative technology to Haber-Bosch for ammonia production. The recording is available on the AEA’s Vimeo channel, and you can download the speaker presentations.
Japan: an energy importer
Japan currently imports a significant portion of its energy needs in the form of hydrocarbons such as coal and LNG (liquefied natural gas). It is estimated that Japan emits in excess of 1 gigatonnes CO2 annually. In its efforts to reach net zero CO2 emissions by 2050, Japan was the first country with a clear vision within the SIP Energy Carriers programme for importing ammonia as zero carbon fuel. As Japan currently imports the vast bulk of its gas and coal, the cost of these fuels is higher than in regions with their own abundant fossil resources. This means the cost gap with zero carbon fuels such as ammonia is actually lower than for other locations.
An example of an early project is the 20% ammonia co-firing to JERA’s 1 GW coal-fired thermal power unit 4 in Hekinan in 2027. This project required about 500,000 tonnes of ammonia annually. Decarbonizing ammonia production is crucial to achieve decarbonization targets in this project. For fully decarbonized ammonia, 20% co-firing in all existing coal power plant units in Japan could result in a CO2 emissions reduction of 40 million tonnes annually, or 4% of Japan’s current national emissions.
Demonstrating low-carbon, fossil-based ammonia in Japan
Japan will be importing most of its ammonia for fuel application. In order to accelerate this development, Japanese companies invest in low carbon ammonia production projects globally. Furthermore, Japanese consortia aim to further develop the necessary technologies for low carbon ammonia production.
An example is an INPEX-led project, which will demonstrate low carbon fossil ammonia production with a capacity of 500 tonnes per year in the Niigata prefecture, starting from August 2025. Natural gas is extracted from a depleted gas field using EGR (Enhanced Gas Recovery), where CO2 is injected into the gas field to force remaining natural gas out, while the CO2 is permanently stored underground. The EGR technology in the project is joint research of INPEX, a Japanese oil and gas company, and JOGMEC, a subsidiary organization of the Japanese government in the field of energy and metals. Hydrogen is produced via autothermal reforming, using Air Liquide technology. Ammonia is synthesized using Tsubame’s low temperature, low pressure ammonia synthesis technology.
EGR (Enhanced Gas Recovery) as part of the decarbonization toolkit
JOGMEC (Japan Organization for Metals and Energy Security) will perform joint research on EGR (Enhanced Gas Recovery) with INPEX. The goal of the project is to acquire knowledge and understanding on EGR. The Minami-Nagaoka gas field operated by INPEX will be used for natural gas extraction, which is subsequently transported by pipeline to the hydrogen and ammonia production plants. The CO2 produced during hydrogen production is then transported to the depleted gas reservoir of the nearby Higashi-Kashiwazaki gas field (abandoned since 2014), in order to extract additional natural gas from the reservoir while storing CO2 at the same time. Thus, EGR can be considered a combination of carbon capture and utilization (CCU) and carbon capture and storage (CCS), e.g. CCUS.
The joint research regarding EGR activities is put in place from 2022 till 2025, including drilling of three new wells: a CO2 injection well, a monitoring well, and a natural gas production well for EGR. Monitoring with for example seismic wave devices is key to understanding the migration of CO2 throughout the reservoir. Geological models are used in combination with CO2 monitoring to predict various characteristics of the reservoir, such as structure, lithology, porosity, and permeability.
EGR has some benefits. It allows the operator to put CO2 back into the ground, which prevents its emission to the atmosphere. By putting CO2 back into the ground, pressure can be maintained when emptying the gas reservoir. Another aspect is the more complete gas extraction. Even without EGR, approximately 60-80% of the natural gas can be recovered from a gas field, but there is potential to further increase the gas recovery rate by injecting CO2 into a reservoir.
CO2 injection into reservoirs is an industrially applied technique within the oil extraction industry, e.g. Enhanced Oil Recovery (EOR), such that materials and technologies for EGR are commercially available. The CO2 produced from various ammonia plants is currently used for enhanced oil recovery. Thus, EGR is part of the toolkit for decarbonizing ammonia production, and also the toolkit for Japan to reach carbon neutrality by 2050. It should be noted, however, that every gas reservoir is different, and dedicated monitoring and simulation is likely required for applying EGR in each scenario.
Tsubame’s low temperature and low pressure ammonia synthesis technology
Tokyo Institute of Technology has a rich history when it comes to research on ammonia synthesis catalysts. Setsuro Tamaru worked in Fritz Haber’s laboratory, and contributed to the foundation of the Tokyo Institute of Technology in 1929. Atsumo Ozaki and Ken-ichi Aika continued the research by improving the understanding of the reaction mechanism and they found that Ruthenium-based catalysts could be more active for ammonia synthesis than the industrially used Iron-based catalysts.
More recently, Hideo Hosono and co-workers developed a more active, electride-supported catalyst. The “electride” is a mixture of calcium oxide and aluminum oxide, with free electron movement. This helps break the triple N-N bond in nitrogen molecules, which is typically the rate limiting step for ammonia synthesis catalysts. The increased activity of these electride-supported catalysts implies that a lower temperature and pressure can be used – about 300-400°C and 50 bar, compared to 400-500°C and 100-300 bar for the conventional Haber-Bosch process with an iron-based catalyst.
Tsubame is commercializing its low temperature and low pressure ammonia synthesis technology, based on the electride-supported catalyst. Since 2017, The milder operation conditions imply lower cost materials can be used for the reactor, heat exchangers, compressors, with the thickness of pipes and vessels also reduced.
Tsubame is developing this technology for distributed low carbon fossil and renewable ammonia production, where investment cost is more important than energy consumption. Local production benefits from the absence of transportation costs, such as shipping and transportation by road.
In 2019, Tsubame launched its 20 tonnes per year pilot plant, which has been running stably for over 3 years. It is expected that the electride-supported catalyst has a lifetime of about 9 years, similar to iron-based catalysts used in Haber-Bosch plants.
By the end of 2022, Tsubame received its first commercial order as part of the INPEX-led project for its TM-500 unit, which produced 500 tonnes of ammonia per year. Tsubame also has standardized modules for 3000 (TM-3000) and 5000 (TM-5000) tonnes per year. The company is currently working on flexible operation to allow for direct coupling with intermittent renewables.