Decarbonisation Technology - November 2024 Issue

However, decarbonising the shipping industry presents a formidable challenge. One of the primary hurdles is the reliance on fossil fuels, particularly heavy fuel oils, which are deeply ingrained in maritime operations. Moreover, ships’ long lifespans, often spanning decades, complicate the rapid adoption of cleaner technologies. Additionally, the diverse nature of the global fleet, comprising vessels of various sizes, ages, and operational profiles, further complicates decarbonisation efforts. Regulatory frameworks, while essential for driving industry-wide change, also pose challenges. The IMO GHG Strategy target is to reduce the carbon intensity of shipping, which is calculated based on the CO 2 emissions produced per tonne-mile of cargo transported, by at least 20% by 2030 and 70% by 2040 compared to 2008 levels. By, on, or around 2050 the target is net-zero emissions. Achieving these targets requires developing and deploying zero-emission vessels powered by alternative fuels or energy sources. Methanol and ammonia as alternative fuels Both methanol and ammonia offer promising pathways towards reducing GHG emissions. Although both have a lower energy density compared to some conventional fuels, they can still provide sufficient energy to power large ships over long distances. This makes

them a practical option for long-haul maritime routes. However, ammonia in liquid form needs to be stored in pressurised tanks or at low temperatures, adding complexity to onboard production and distribution infrastructure. It is widely produced and used in industries such as agriculture and chemicals, facilitating its integration into the maritime fuel supply chain. Furthermore, it can be synthesised using renewable energy sources through processes like electrolysis, which produce green hydrogen that is then combined with nitrogen from the air to produce green ammonia. This green fuel storage and handling systems. Ammonia has an established global ammonia production pathway makes ammonia a sustainable marine fuel option, contributing to a significant reduction in emissions and one that will certainly support the industry in the future. Methanol, on the other hand, has lower toxicity than ammonia, reducing safety concerns for marine habitats and during handling, storage, and bunkering operations. It also has significant advantage in the short term as methanol engines are already commercially available and in production. Like ammonia, grey methanol is widely produced today and has established infrastructure, making integrating it into existing supply chains and refuelling infrastructure easier. This existing infrastructure reduces the upfront investment required for adoption and facilitates a smoother transition for maritime operators.

Different routes to sustainable methanol In traditional operations, methanol is primarily derived from synthesis gas sourced from fossil fuels. However, as renewable methanol production expands, it offers a viable solution for the decarbonisation of diverse transportation sectors, including shipping. Both e-methanol and biomethanol offer renewable and lower carbon intensity pathways to decarbonise shipping. Production relies heavily on the choice of feedstock, each with

In e-methanol plants, the recycle ratio emerges as a critical design parameter, impacting feedstock efficiency and production costs