Overview of the Process Steps for the Two Scenarios

As already stated, the functional unit in this study is the fertilization of 1 ha of land in Cote d’Ivoire, on which cacao trees are grown together with shadow trees. In Table 8.10, an overview is given of the process steps for the two scenarios. As can be seen from Table 8.10, several process steps are identical for both scenarios. This means that these process steps are not taken into account.

8.4.2 Scenario 1: Recycling of the Ashes as a Fertilizer

The filter ash is transported by means of a heavy lorry trailer from the bioenergy plant to the port. The distance between these is assumed to be 100 km. Table 8.3 gives the emissions per ton kilometer. Per hectare cacao plantation in Cote d’Ivoire, 74 kg cacao shells are produced, resulting in 6.7 kg filter ash, corresponding to 0.67 t km. The filter ash is transported by means of a bulk carrier from the Dutch port to Cote d’Ivoire. The distance is assumed to be 6,000 km (SenterNovem 2007), which results in 40.21 km. The ash is transported by means of a medium-sized lorry from the port in Cote d’Ivoire to the cacao plantation. The distance is assumed to be 800 km, which results in 5.4 t km.

Table 8.10 Overview of the process steps for PK fertilization of 1 ha cacao plantation in Cote d’Ivoire (N fertilization excluded)

Process step

Scenario 1

Scenario 2

Production of cacao beans in Cote d’Ivoire

740 kg dried beans

Transportation of cacao beans from Cote d’Ivoire

740 kg fried beans

to the Netherlands

6,000 km

Production of cacao shells

74 kg cacao shells

Transportation of cacao shells to bioenergy plant

74 kg cacao shells 100 km

Combustion in bioenergy plant

74 kg cacao shells 6.7 kg filter ash

Transportation of ash to port in the Netherlands

6.7 kg filter ash 100 km

Transportation of ash to salt mine in Germany

6.7 kg filter ash 250 km

Transportation of ash to Cote d’Ivoire

6.7 kg filter ash 6,000 km

Transportation of ash to cacao plantation

6.7 kg filter ash 800 km

Production of fertilizer in Cote d’Ivoire

113 kg triple

114 kg triple

superphosphate

superphosphate

125 kg potassium

129 kg potassium

chloride

chloride

Transportation of fertilizer in Cote d’Ivoire

238 kg PK fertilizer

243 kg PK fertilizer

800 km

800 km

Table 8.11 Overview of the CO2, NOx, and SO2 emissions caused by scenarios 1 and 2 for PK fertilization of 1 ha

CO2

(kg)

NOx

(g)

SO2 (g)

Scenario 1

Transportation of ash from bioenergy plant to Dutch port

0.04

0.66

0.03

Transportation of ash from Dutch port to Cote d’Ivoire

0.32

8.4

8.0

Transportation of ash from port in Cote d’Ivoire to cacao plantation

0.84

14

0.62

Production of PK fertilizer

145

487

2,004

Transportation of fertilizer to cacao plantation

30

487

22

Total

175.5

997

2,034

Scenario 2

Transportation of ash from circulating fluidized bed combustion plant

0.10

1.7

0.08

to German mine

Production of PK fertilizer

147

493

2,033

Transportation of fertilizer to cacao plantation

30

498

22

Total

177.1

993

2,056

Difference (scenario 2 minus scenario 1)

1.6

-4.4

21

The major part of the PK nutrient demand has to be provided by synthetic fertilizer. Table 8.7 shows the emissions produced by 1 kg of these fertilizers. These emissions are valid for production of the fertilizer in Europe. We assume the production of the fertilizers takes place in Cote d’Ivoire. However, because of lack of better data, the production data for Europe are used. The fertilizer (238 kg) is transported within Cote d’Ivoire by means of a medium-sized lorry. The distance is assumed to be 800 km, corresponding to 190 t km. In Table 8.11, an overview is given of the total emissions in scenario 1.