In this case it is assumed that the beans are transported to the Netherlands. The beans are stored in the harbor before transport to the cacao processing plant. Beans are broken to nib and the shells are separated. The nib is processed to cacao products. The shells are combusted or used as gardening material. All materials are transported by road or water. An example of cacao shells is given in Fig. 8.3.

For the scenarios it is assumed that the cacao shells are combusted in a circulat­ing fluidized bed combustion plant to produce heat and power. This is a type of boiler for production of energy from biomass on a large scale (so-called bioenergy

flue gas

plants) (Fig. 8.4). The general data of the bioenergy plant that were used in this study are given in Table 8.1. Sand is used as bed material. Some limestone is used to capture sufficient SO2 to meet the Dutch emission requirements.

The predicted chemical composition of the filter ash is presented in Table 8.2. The macroelements are also expressed as oxides (this does not mean that these elements

are present as oxides). The main nutrients in filter ash are potassium, calcium, and phosphorus. Thermodynamic calculations were performed to predict the potential compounds in cacao ash under equilibrium conditions. These were performed using FactSage©. The main compounds will be K2SO4, K2CO3, and Ca5HO13P3. It is assumed that the filter ash contains 5% residual pyrolized cacao shells (carbon).