Decarbonisation Technology November 2026 issue

block at the front of the value chains related to ammonia, methanol, and a host of petrochemicals. In China, coal is gasified to make syngas, which is converted to ammonia, petrochemicals, and hydrocarbon fuels. In both steps, CO2 is formed and released to the atmosphere. All around the world, coal is converted to coke for use in iron and steel making. During the coking process, syngas is created, which can be used as a fuel and a reducing agent in the blast furnace. When forestry waste biomass is gasified, it also releases CO2, which can be captured and sequestered or utilised. In this case, the CO2 capture, utilisation, and release cycle is generally less than 50 years. When natural gas is reformed to make syngas, and the syngas is shifted to hydrogen, CO2 is formed in large quantities. As an alternative to atmospheric release, CO2 generated from coal gasification and natural gas reforming can be captured and then sequestered in sub-surface geological formations. Syngas produced this way may be considered ‘blue’ syngas. It is the precursor of ‘blue’ hydrogen. One of the most effective techniques for blue syngas production is gas heated reforming (GHR) combined with autothermal reforming (ATR). This configuration minimises low-pressure post-combustion CO2 capture and thereby reduces the cost of achieving a high CO2 capture rate (see Figure 1 ). e-CO for green syngas Electrification with renewable electricity is one of the most technically mature and scalable routes to clean molecules. The main hurdle holding this pathway back is the cost of electricity. The economics of electrically driven chemical conversions, such as electrolysis of water to hydrogen, shift from unfavourable to favourable if low-cost power can be used. In mature electricity markets with a high degree of renewables penetration and fluctuations in daily demand, prices can swing from peak to trough in less than an hour. The number of hours of negatively priced electricity is rising each year. Under these circumstances, the most economically advantageous operating mode shifts from a high-utilisation paradigm to an intentionally intermittent profile: operating when power prices are low.

To exploit intentionally intermittent operation, the equipment and process must be hyper-flexible and tolerant of extended idle periods. This favours lower-temperature operation to minimise the thermal mass, reactor configurations that perform well across a wide range of operating conditions, and a process with recycle loops that can help absorb the shock of rapid throughput changes. Sisyphus Energy in Leoben, Austria, has implemented these concepts in an electrically heated, reverse water-gas shift (RWGS) reactor concept. The company’s expertise is in the integration of cutting-edge materials development with scalable reaction configurations. Its e-RWGS reactor can be fed with green hydrogen from intentionally intermittent electrolyser operation and captured CO2 to yield CO, one of the two main components of syngas. The first innovation that makes the process unique is an improved RWGS catalyst with high selectivity to CO at low operating temperatures. This a significant advancement because traditional RWGS catalysts tend to produce methane at low temperatures. When syngas is the target, CO is helpful, but methane is not. Downstream of the RWGS reactor, Sisyphus has engineered a functional material that is highly selective to CO. Other gases are recycled to maximise energy efficiency. Pulling the CO product out of the process stream, rather than removing individual impurities, is key to its integrated process. The e-CO can be used for low-carbon chemical synthesis, notably reducing the CO2 intensity of speciality chemicals and pharmaceuticals. Alternatively, when the resultant e-CO is blended with green hydrogen, e-syngas is the product and methanol or FTS fuels can be produced at scale. The process flowsheet developed by Sisyphus Energy is optimised for flexibility, which improves its economic viability and accelerates the path to producing net-zero chemicals and fuels at cost parity with fossil-based equivalents. Dry methane-reforming and turquoise hydrogen Chemical reactions, such as reforming, rearrange molecules in the feedstock to syngas. A plasma arc can be used to activate these molecules by splitting them and letting them recombine into more favourable products. Essentially, it is an electrified process for molecule conversion.