The E-TANDEM project continues to develop sustainable e-fuels through their efforts towards a once-through production process of Higher Oxygenates E-Fuels (HOEFs). By completing Deliverable 3.2 on the fuel ignition behaviour and Deliverable 3.3 on fuel-components interaction, E-TANDEM has successfully achieved Milestone 5, which focusses on the fuel performance and compatibility of HOEFs in real world applications. Two e-fuel realizations were studied, consisting either of a mixture of higher (C4+) aliphatic alcohols (alcohol-based HOEF), or a mixture of higher (C10+) aliphatic ethers (ether-based HOEF). Key characteristics such as cetane number, oxidation stability and flash point were determined, as well as ignition properties including the formation of soot during combustion. Both fuels were also blended with Marine Gas Oil (MGO), as a relevant benchmark fuel, to investigate the possibility of blending HOEFs into existing fuels to de-fossilize waterborne transport in the short term.
Both e-fuels met different prescriptions set out in the Marine Gasoil ISO standard 8217 for applications in marine transport even in neat forms, including oxidation stability, flash point (alcohol-based HOEF) and cetane index (ether-based HOEF). Furthermore a much cleaner combustion, with significant reduction in soot production compared to MGO, was observed. Both HOEF realizations showed to form stable blends with MGO. Particularly fuel blends incorporating ether-based HOEF showed improved combustion properties (boosted cetane index) alongside reductions in soot production as high as 30-50%, depending on the blend formulation.
Compatibility tests were completed for typical engine materials, including various metals and polymers, using a 20% ether-based HOEF blend with fossil MGO. None of the tested materials exhibited unacceptable degradation after six months of exposure to the e-fuels. Accelerated-aging tests likewise revealed no critical issues and, notably, indicated a beneficial effect of HOEF in preventing (and even reversing) carbonaceous deposit formation on engine injectors. These findings indicate that long term application of these e-fuel blends shall not result in extra damage to current-fleet engines, and support drop-in uptake of the renewable fuel as a major blending component.
By completing Milestone 5, the E-TANDEM project continues to show the promise of HOEFs as a sustainable alternative to fossil fuels in marine transport and heavy-duty road transport.
