Utilisation of Synthetic Fuels for "Difficult-to-Decarbonise" Propulsion

运输部门的脱碳是全球的首要任务。难以脱碳的运输应用（主要包括航运、公路货运和航空）排放的二氧化碳占整个运输部门的50%以上。在开发低排放燃料的努力中，可以大量减少污染物排放的液体合成燃料越来越受到关注，因为它们可以利用现有的基础设施整合到现有的运输系统中，并作为插入燃料在现有的发动机（如柴油发动机，以获得最佳的燃油经济性）中燃烧。液体合成燃料，如甲氧甲烷醚（OMEx，当x=3-5时具有与柴油相似的液体特性）可以从一系列废弃原料和生物质中生产，从而避免新的化石碳进入供应链。OMEx也可以作为电燃料（或电子燃料）生产，从而用作可持续的能源载体。然而，由于缺乏与燃料成分变化相关的物理化学特性的完整知识，即低聚物长度（OMEx的x值）的变化以及OMEx-柴油混合物在实际发动机环境中的成分变化，因此在实际发动机中使用OMEx存在挑战，主要是在发动机及其操作调整中，以获得最佳性能和最小的污染物排放。为了解决OMEx利用的技术问题，合成燃料在发动机工作范围内的物理化学性质和污染物排放的准确信息是强制性的，但这些信息并不容易获得。本项目旨在全面了解液体合成燃料的利用。该项目将解决利用可再生合成燃料的基本挑战，特别是OMEx和相关的OMEx-柴油燃料混合物。该研究将采用建模/模拟-实验相结合的方法，使用分子动力学模拟预测替代燃料的物理化学特性，包括排放特性，为燃料利用的第一手信息量身定制的实验，并建立数据库/映射，以指导实际发动机在广泛条件下使用机器学习的合成燃料利用。

Decarbonising the transport sector is a top priority worldwide. The difficult-to-decarbonise transport applications (including mainly shipping, road freight and aviation) emit more than 50% CO2 of the entire transport sector. Among efforts on developing low-emission fuels, liquid synthetic fuels that can massively reduce pollutant emissions are drawing increasing attention, as they can be integrated into the current transportation system using existing infrastructure and combusted in existing engines (such as diesel engines for optimal fuel economy) with minor adjustments as drop-in fuels. Liquid synthetic fuels such as oxymethylene ethers (OMEx, which possess liquid properties similar to diesel when x=3-5) can be produced from a range of waste feedstocks and biomass, thereby avoiding new fossil carbon from entering the supply chain. OMEx can also be produced as an electrofuel (or e-fuel), thereby used as a sustainable energy carrier. However, due to the lack of complete knowledge of the physicochemical properties associated with the fuel composition variability, i.e. variation in the oligomer length (the x value of OMEx) and the composition variation of OMEx-diesel blends in real engine environment, there are challenges in utilising OMEx in practical engines, mainly in engine and its operation adjustments for optimal performance and minimal pollutant emissions. To address the technical issues of OMEx utilisation, accurate information on physicochemical properties and pollutant emissions of the synthetic fuels over the engine operational ranges is mandatory, but this is not readily available.This project is intended to obtain a thorough understanding on liquid synthetic fuel utilisation. The project will address the fundamental challenges in utilising renewable synthetic fuels, in particular OMEx and the associated OMEx-diesel fuel blends. The study will follow a combined modelling / simulation - experimentation approach, predicting the physicochemical properties including emission characteristics of the alternative fuels using molecular dynamics simulations, tailor-made experimentation for first-hand information on fuel utilisation, and establishing a database / mapping to guide the synthetic fuel utilisation in real engines over a wide range of conditions using machine learning.