Evaluation of Different Pretreatment Systems for the Energy Recovery of Greenhouse Agricultural Wastes in a Cement Plant

This work evaluates and selects the best sequence of operations for the pretreatment of greenhouse agricultural wastes (GAW) derived from the main greenhouse crops of the west of Almeria (Spain), such as tomatoes, peppers, cucumbers, eggplants, zucchinis, watermelons and melons, before recovering its potential energy in a cement plant located in this province. In this research, a set of operations are proposed to reduce the chlorine percentage and the moisture content presented in this kind of waste, for its use as an alternative fuel in this production facilities. A washing of the waste under optimal conditions may reduce the chlorine content by approximately 50.0% of the original value and increase the lower calorific value by 8.0%. Drying the waste with a hot gas stream could produce a recoverable waste with a moisture content lower than 3.0%, which enables its temporary storage while avoiding its degradation. The use of an adequate amount of conditioned GAW can provide a substitute up to 51% of the conventional fossil fuel currently employed in the daily operation of the facility evaluated, leading to a reduction of the CO2 emissions associated with the decrease in the fossil fuel consumption.