Comparative Analysis of Partially Renewable Composite Fuels Based on Peat, Lignite and Plant Oil

Abstract

The inevitable depletion of exploited fossil fuel deposits motivates the investigation of every possibility of saving them. One of the ways to do that is to combine fossil fuels with renewable plant-derived fuels. This paper studies the specific aspects of the thermochemical conversion of composite fuels consisting of peat or lignite with rapeseed oil. It was shown that mixtures of peat or lignite with rapeseed oil can be successfully gasified when the temperature is higher than 700–800 °C. The self-sustaining combustion of these fuels does not support such high temperatures, and thus the process requires external heating. The obtained optimal component ratio for peat-oil and lignite-oil compositions is about 1:2 and 3:2, respectively. Such mixtures allow the most efficient usage of the oxidation heat during conversion. The high calorific value of such fuels is very close to that of rapeseed oil (38.5 MJ/kg), even for the lignite-oil composition with 40 wt% lignite. Lower overall prices of fossil fuels compared to pure renewable plant-derived fuels help reduce costs and save valuable fossil fuels.