integration of solid oxide fuel cells and ... - Ea Energianalyse

2.2. Auxiliary Power Unit (APU)
Sensitivity analysis of Ship ABS vs ECH
15
10
Annuity increase [%]
5
0
-10 -5 0 5 10
-5
-10
Purchase price ABS
Purchase price EAC
Diesel price
Efficiency SOFC
Usage time fraction
Discount rate
-15
Increase in variables [%]
Figure 2.1: The percentage increase in annuity gain is shown for a 10% increase of the input
parameters. The annuity is for a lifespan of 10 years. The purchase price of the ABS unit is
200.000DKK. With the chosen parameters the gained annuity is 75.000DKK/y (incl purchase).
price of the ABS unit, however, gives only a 3,5% decrease of the annuity
for a 10% increased price, and the ECH price and discount rate gives even
smaller changes. So the lack of exact knowledge about the price turns out
not to be so critical after all.
The reason for the huge influence from SOFC efficiency and diesel
price is that these factors are determining the price of the electricity
generated for the electrical chiller.
Pay Back Time vs. usage time fraction
As long as the usage time fraction is above 30%, the investment seems to
be quite beneficial (pay back time less than 3 years), but if the usage time
fraction comes below 20%, the pay back time starts to increase quickly.
So for a usage time fraction of 10%, the pay back time is just under 10
years, which is far too long for many companies.
23