From the test-tube to the test-engine: assessing the suitability of prospective liquid biofuel compounds

Abstract

In the recent years, research efforts for the exploitation of biomass for the production of alternative fuels for automotive internal combustion engines has increased tremendously. However, it is still uncertain and a matter of debate what the chemical composition of future biofuels will be. Up to now, the applicability of a prospective biofuel compound can only be analysed using test engine runs. However, as these engine based tests require large quantities of the biofuel candidate (usually at least several litres) and high-cost, specialized equipment alternative strategies for the assessment of small quantities are sought for. However, a multitude of properties has to be considered when assessing the suitability of a chemical substance as seminal biofuel. In this article the selected key properties allowing an initial fuel characterization for diesel-like fuels are discussed, including i) ignition properties: the cetane number, ii) calorific value, iii) greenhouse gas emission, iv) miscibility with a reference substance, v) viscosity and cold-filter-plugging point (CFFP), vi) boiling range and volatility. Thereby, in order to allow an assessment of prospective biofuel compounds already in test tube volumes (i.e. several millilitres), we define a first suggestion for a catalogue of key parameters that can routinely be assessed in chemical laboratories.