Palm oil kernel shell as solid fuel for the commercial and industrial sector in Ecuador: tax incentive impact and performance of a prototype burner

The Ecuadorian industrial and commercial sectors are in general supported in the use of diesel for energy purposes. An alternative to replace diesel could be the use of palm oil residual biomass as solid fuel. It is estimated that 57.7% of the capital costs required to implement a biomass boiler that use untreated palm oil kernel shell (KS) as fuel in replacement of a diesel boiler would be covered by in force tax incentives. Nonetheless, untaxed and subsidized diesel utilization coupled to the important capital and operating costs associated to the biomass boiler results in relatively high payback periods, within the range of 6 to 7.9 years. Analyzing a base case, it is observed that replacement of diesel by KS results in a reduction of 8 times the fuel costs. Implementation of pre-treatment processes (e.g. pelletizing) could increase the KS price, affecting the potential to lower the costs of thermal energy production. Accordingly, utilization of raw KS for thermal energy production was demonstrated using a horizontal burner prototype. The experimental analysis of the KS combustion process shows that combustion efficiency (99.8%) is as high as that observed in other type of biomass burners. During the steady state operation periods, CO concentration in the flue gases (260.1 mg/Nm3) was below the limit established by the European standards for solid fuel boilers (500 mg/Nm3). Ash sintering was observed in the grate during the combustion experiments. The ash discharge process induced periodic fluctuations in the combustion chamber temperature profile as well as fluctuations in the flue gas composition. Despite these localized and periodic temperature and gas composition fluctuations, in the whole, and considering longer periods of operation, the combustion system was under steady state conditions and showed to be suitable for energetic valorization of untreated KS.