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5.4 Economic evaluation of electricity generation costs at Giriulla mill

Overall power costs of the system can be calculated on the following assumptions:

System cost

US$ 32000 (Hfl. 90000)

System life-time

6 yrs

Interest rate


Maintenance costs

10 percent per year of initial investment 1/

Additional labour costs

1 man-yr

Coconut shell costs

US$ 6.00/t


4000 h/yr

Those assumptions lead to the following breakdown of annual costs:

Annual Capital charges 2/

US$ 7350



Additional Labour




Fuel (140 ton coconut shell)


Annual Cost

US$ 13690

Energy produced (4000 h x 20 kW)

80000 kWh

Unitary cost

0.171 US$/kWh

Those costs compare favourably with a diesel generation system, for which the costs under comparable circumstances would be around 0.26 US$/kWh.

1/ Assumed
2/ Annual capital charges are calculated using the relationship:

in which:

C = capital costs
i = annual interest rate
t = lifetime of system

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