Title : Techno-Economic analysis of methanol and ammonia production as a sustainable fuel from green hydrogen
Abstract:
In this study, two different power-to-fuel solutions for sustainable fuel synthesis are investigated from the energetic, environmental, and economic standpoints. Both the solutions consider a 10 MW alkaline electrolysis section, fed by renewable wind energy, where high purity green hydrogen is produced. Then, two separate processes are investigated for the synthesis of two distinct chemicals with prices in Türkiye. In the first case, the hydrogen is mixed with CO2, sequestered by an industrial plant, and produced from a biogas plant: the two gases are sent to a pressurized reactor for methanol synthesis. In the second case, the hydrogen is mixed with N2, obtained from an industrial air separation unit (ASU), and sent to a reactor for ammonia synthesis. Both the synthesis processes are performed at high pressures and temperatures. In both cases, the power to fuel plants is investigated in economic terms. Methanol synthesis presents a slightly higher efficiency compared to ammonia, while the two solutions are very similar from the economic standpoint. The sale of the co-produced oxygen allows for an improvement in economic terms for both cases and can be a key point in order to reach economic sustainability, together with the expected reduction in electrolysers capital cost.
Audience Take Away:
Renewable methanol produced from captured off gas CO2 and non-fossil hydrogen can replace fossil hydrocarbons in a huge swathe of industrial and domestic sectors bring them ever-closer to carbon neutrality. The global market for methanol as a fossil substitute is predicted to be 500mt by 2050. The applications for methanol are already widespread due to its desirable properties. It can be transported and stored easily and safely, being a liquid at room temperature. It is biodegradable and a highly efficient energy carrier, burning cleanly and producing no soot or particulates. Methanol is commonly used as a chemical feed stock for the production of plastics, glue, building materials, paints and solvents and is the most commonly used carbon source for removing contaminants from wastewater.
Methanol has a high Octane rating (109 RON) providing better energy conversion than either gasoline or diesel. In many regions different blends of methanol with gasoline diesel are in use, with 3% and 15% already seen in Europe and China respectively. Authorities in China are also promoting M100 (100% methanol) in light vehicles, buses and trucks. Marine transport is increasingly turning to methanol as a clean replacement for bunker fuel and it continues to grow in popularity for industrial boilers and cook stoves.
Renewable methanol is easier and safer to store and transport than hydrogen, and actually contains a higher density of hydrogen than the equivalent liquid volume of pure H2. It has diverse fuel applications and a large demand as an existing feed stock for the chemical industry. Therefore, renewable methanol is able to technically, economically and practically reduce the greenhouse gas emissions of significant sections of the global economy.
Ammonia is an important basic raw material for inorganic and organic chemical industries, which can be used in chemical fertilizer, pharmaceuticals, oil refining, soda ash, synthetic fibers, synthetic plastics, nitrogen-containing inorganic salts, etc. Ammonia is expected to be a zero-carbon energy carrier in the future, like being a fuel for automobiles, ships, aircraft and other engines, and replacing gas/oil as a fuel for industrial boilers or civil stoves. Ammonia is also one of the main carriers of hydrogen energy. However, 98% of the feedstock for ammonia production comes from fossil fuels. With the intensification of global warming and environmental issues, it is inevitable to find an appropriate green alternative to achieve low energy consumption, low emission, sustainable and efficient ammonia production. Green ammonia production is where the process of producing ammonia is 100% renewable and carbon-free. One way of producing green ammonia is by using hydrogen from water electrolysis and nitrogen separated from the air.
Renewable methanol production has an efficiency of about 52%, while renewable ammonia production presents a slightly lower value (50%) due to higher energy consumption in compressors. Ammonia shows its superiority compared to methanol as a hydrogen carrier, as it can store a considerable amount of H2 in its structure. On the other hand, methanol production with the described process allows for the utilization of a considerable amount of CO2, with a positive impact in environmental terms. The production costs are higher than the market values of both renewable ammonia and methanol, the option of selling the co-produced O2, together with a reduction of hydrogen electrolysers capital costs can considerably improve the economic feasibility of both the renewable ammonia and methanol production. Electricity is the most important cost in renewable ammonia and methanol production, in both cases accounting for more than 65% of the production cost in Türkiye. Regarding synthesis units, ammonia is more expensive than methanol, mostly due to the lower single pass conversion that imposes higher operating pressure and temperature and a higher recirculation rate.
