Fuelling Micro Gas Turbines With Vegetable Oils: Part I — Straight and Blended Vegetable Oil Properties

Current energy policies tend to encourage the production of renewable energy for environmental reasons and energy independence. Among renewable sources, biomass can play a key role, because of economic, environmental and political factors, such as the need to diversify and improve energy supply, reduce the greenhouse effect and support rural areas. For the case of liquid biofuels derived from agricultural crops, several possibilities can be considered, such as straight vegetable oil (SVO), oil-derived esters, bioethanol or blends with conventional fuels (diesel or gasoline). The use of SVOs and their derivatives usually poses some problems, that essentially derive from their much higher viscosity and higher boiling temperature. In order to evaluate the technical feasibility of the use of SVOs within gas turbine combustors, this paper reports the results of the experimental characterization of different vegetable oils, derived from dedicated crops. Moreover, blends composed of diesel and vegetable oil in different concentrations (from pure diesel to pure vegetable oil) are also considered and their experimental characterization is also reported, with particular focus on blend viscosity. The considered vegetable oils were obtained from different types of oilseeds (rapeseed, sunflower, soybean) and were cultivated under different agronomic scenarios. The SVO properties determined experimentally are SVO elemental composition, lower heating value, density, specific heat and viscosity, for which this paper provides a practical overview, coming both from experiments and literature data.