Influence of Blending Model Butanol Alcoholysis-Derived Advanced Biofuel Components with Hydrotreated Vegetable Oil on the Physical Properties, Combustion, and Emissions Performance of a Compression Ignition Engine

As fossil fuels are being replaced by lower-carbon alternatives, the EU renewable energy directives RED II/III mandate increases in the proportion of advanced biofuels within liquid fuels, aiming to reduce greenhouse gas emissions over first-generation biofuels. It is crucial to study how these fuels affect engine performance to ensure they also meet emissions standards of relevance to air quality. Advanced biofuels, mainly from lignocellulosic feedstocks, are promising options. This work tested model butanolysis-derived blends using hydrotreated vegetable oil (HVO) as the base fuel, due to its lower carbon footprint, favourable combustion properties, and potential to replace diesel without engine modifications, along with ultra-low sulphur diesel (ULSD). Physical properties such as density and flash point were tested on the butyl-based biofuel blends. The measured densities fell between those of pure HVO and ULSD, while the measured flash points exceeded the minimum standards required for fuels. This study examines the use of such blends with a EU Stage V emission compliant Yanmar L100V compression ignition (CI) engine as part of a generator set, using model butanolysis biofuel mixtures blended with HVO at various ratios. A CI engine was chosen because generators, off-road machinery, heavy-duty vehicles, and marine vessels will continue to rely on CI engines for the foreseeable future. Ignition delays (IDs), brake-specific fuel consumption (BSFC), gaseous and particulate matter (PM2.5) emissions were determined. Gaseous emissions were measured with a Horiba MEXA7100D, and PM2.5 was collected on filters for gravimetric analysis. All blends, including pure HVO, had shorter IDs than diesel. Emissions of nitrogen oxides (NOx = NO + NO2), carbon monoxide (CO), and total hydrocarbons (THC) decreased compared to diesel. PM2.5 levels dropped with the additions of advanced biofuels relative to pure HVO and ULSD. CO emission factors were below EU Stage V limits, but slight exceedances occurred for THC and NOx.