energies Article Alcohol Fuels for Spark-Ignition Engines: Performance, Efficiency, and Emission Effects at Mid to High Blend Rates for Ternary Mixtures James W. G. Turner 1,* , Andrew G. J. Lewis 1, Sam Akehurst 1 , Chris J. Brace 1, Sebastian Verhelst 2 , Jeroen Vancoillie 2, Louis Sileghem 2, Felix C. P. Leach 3 and Peter P. Edwards 3 1 Institute for Advanced Automotive Propulsion Systems, University of Bath, Bath, Somerset BA2 7AY, UK; [email protected] (A.G.J.L.); [email protected] (S.A.); [email protected] (C.J.B.) 2 Department of Electromechanical, Systems and Metal Engineering, Campus UFO, Ghent University, T4, Sint-Pietersnieuwstraat 41, B-9000 Gent, Belgium; [email protected] (S.V.); [email protected] (J.V.); [email protected] (L.S.) 3 Departments of Chemistry and Engineering Science, University of Oxford, Oxford OX1 3PJ, UK; [email protected] (F.C.P.L.); [email protected] (P.P.E.) * Correspondence: [email protected]; Tel.: +44-1225-383466 Received: 21 October 2020; Accepted: 25 November 2020; Published: 3 December 2020 Abstract: This paper follows on from an earlier publication on high-blend-rate binary gasoline-alcohol mixtures and reports results for some equivalent ternary fuels from several investigation streams. In the present work, new findings are presented for high-load operation in a dedicated boosted multi-cylinder engine test facility, for operation in modified production engines, for knock performance in a single-cylinder test engine, and for exhaust particulate emissions at part load using both the prototype multi-cylinder engine and a separate single-cylinder engine. The wide variety of test engines employed have several differences, including their fuel delivery strategies. This range of engine specifications is considered beneficial with regard to the “drop-in fuel” conjecture, since the results presented here bear out the contention, already established in the literature, that when specified according to the known ternary blending rules, such fuels fundamentally perform identically to their binary equivalents in terms of engine performance, and outperform standard gasolines in terms of efficiency. However, in the present work, some differences in particulate emissions performance in direct-injection engines have been found at light load for the tested fuels, with a slight increase in particulate number observed with higher methanol contents than lower. A hypothesis is developed to explain this result but in general it was found that these fuels do not significantly affect PN emissions from such engines. As a result, this investigation supplies further evidence that renewable fuels can be introduced simply into the existing vehicle fleet, with the inherent backwards compatibility that this brings too. Keywords: alcohols; gasoline-alcohol blends; ternary blends; renewable fuels; e-fuels 1. Introduction The affordability of transport for the end-user is the key factor in the success of the motor vehicle, which has accelerated mankind’s economic development since its inception; cheap transportation is a driver of economies worldwide and this was not possible before the internal combustion engine (ICE). This state of affairs has arisen solely because of its cost-effectiveness and the resulting affordability and utility of the vehicles it is fitted to, coupled to the fact that liquid fuels make the storage and distribution of the energy that they require similarly cost-effective. 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Projected productionproduction volumes volumes of of cars cars split split into in ditoff differenterent propulsion propulsion types types (data (data adapted adapted from fromthat giventhat given in [2]). in BEV: [2]). batteryBEV: battery electric electric vehicle; vehicle; HEV: hybridHEV: hybrid electric electric vehicle; vehicle; PHEV: PHEV: plug-in plug-in hybrid hybridelectric electric vehicle. vehicle. ICE: internal ICE: internal combustion combustion engine. engine. Energies 2020, 13, 6390 3 of 31 Energies 2020, 13, x FOR PEER REVIEW 3 of 32 100 5000 80 4000 60 3000 40 2000 20 1000 Cars / [Millions] Manufactured Year per Cumulative Cumulative Cars Manufactured / [Millions] 0 0 2005 2010 2015 2020 2025 2030 2035 Year / [-] ICE (all) Cumulative Cars Manufactured Figure 2. Data from Figure1 reworked to show vehicles with an internal combustion engine fitted Figure 2. Data from Figure 1 reworked to show vehicles with an internal combustion engine fitted (i.e., pure ICE and hybrid vehicles). The values for cumulative cars built is the same as on Figure1. (i.e., pure ICE and hybrid vehicles). The values for cumulative cars built is the same as on Figure 1.