Blend for all or pure for few? Well-to-wheel life cycle assessment of blending electricity-based OME3–5 with fossil diesel

Abstract

The well-to-wheel environmental impacts of blending electricity-based polyoxymethylene ethers of chain length three to five (OME_3–5) with fossil diesel are evaluated, depending on the availability and the environmental impacts of electricity for fuel production. OME_3–5 is considered a promising substitute and blending component for fossil diesel. We account for the entire life cycle of production, blending, and use of OME_3–5 with fossil diesel, considering alternative blending ratios and combustion emissions from single-cylinder engine tests. For OME_3–5 production, our analysis identifies an aqueous route via methanol and formaldehyde as the route with the highest exergy efficiency and the lowest environmental impacts among four considered routes. In terms of the carbon footprint of the entire life cycle, diesel-OME_3–5 blends can only compete with fossil diesel if low-carbon electricity is used for the supply of electricity-based feedstocks and energy. With low-carbon electricity being available, an increased blending ratio of OME_3–5 with fossil diesel reduces the carbon footprint as well as NO_x and soot emissions. The actual reduction potential additionally depends strongly on the blending ratio. Since low-carbon electricity is limited, it should be used in such a way that environmental impacts are minimal. For the electricity-based fuel OME_3–5, this is achieved when distributing OME_3–5 as a blend component to all fleet vehicles simultaneously instead of switching only a few vehicles to pure OME_3–5, i.e., “blend for all” is favorable over “pure for few.”