8.2.1 Methodology and Starting Points

The starting point is that the whole chain has to be analyzed to assess the environ­mental effects involving closure of the nutrient and mineral cycle. Interviews with representatives from the cacao industry and a literature study were used to define the parameters and to describe the scenarios. The most important part of this chain analysis is the definition of the parameters. The so-called base unit is the most important issue, as it expresses the product under study. The functional unit in this study is fertilization of 1 ha of land in Cote d’Ivoire, on which cacao trees are grown together with shade trees. Further, the effect categories have to be determined, which are the parameters of environmental impact, namely, the nutrient balance and the CO2, NOx, and SO2 emissions.

The starting points for this study are:

— The cacao plantation is situated in Cote d’Ivoire, and the beans are transported to the location of the cacao industry in the Netherlands.

— The cacao shells are a 100% natural residue of the beans and are thermally processed in a stand-alone power plant (so-called bioenergy plant) in the Netherlands.

— The efficiency of the nutrients is comparable to that of the commercial fertilizers which are used on the plantation. Also, the effect of trace elements and

contaminants which are present in the ashes is comparable to that of the commercial fertilizers.

The chemical composition of the ashes is predicted with a modified version of the KEMA Trace Model® (KEMA 2005). The model is an empirical and statistical computer model to predict emissions and ash composition of a dry pulverized coal — fired boiler including biomass co-combustion. A modified version of the model has been developed for fluidized bed boilers, taking into account the lower combustion temperature, the use of inert or reactive bed material, and the distribution of ash and bed material.