6.
ECONOMIC EVALUATION OF MH SYSTEMS' BALLAST WATER TREATMENT
SYSTEM
FOR A 300,000 DWT TANKER |
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| In making an economic
evaluation, the analysis methodology described in Mackey
et al. (2000) was used. This method states, "a logical
basis for economic comparisons would be a change in Required
Freight Rate (RFR)." Since there would be no change in
cargo capacity, then: |
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Mackey et al.
(2000) stated that the economic payback period for conversions
is typically 5 years.
The Authors selected a 300,000 DWT
tanker for analysis. As stated earlier,
a ballast water treatment system applicable
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Table
3.
[click image to enlarge]
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for ships must have the capacity for
treating huge quantities of ballast water. If a system
is practical and economical for treating a ship with 8
ballast tanks of 110,823 cubic meters, then it is practical
for all ship types. The economics would have to be assessed
for ships of other, smaller ballast capacity, as the economics
might not scale. But obviously, the effectiveness as
well as the practicality of the system
would be established.
Table 3
lists the principal parts and materials in the ballast
water treatment system together with estimated prices
and labor costs.
The
total cost is approximately $3,057,100. All tankers already
have some type of inert gas generating capability. The
newer tankers have generators with a gas mixture discharge
similar to the mix used in the experiments at Scripps.
Nevertheless, for conservatism, the generator has been
included in the cost. Similarly tankers probably have
sufficient excess electrical capacity to supply the load
of this equipment - the compressors and blower. This is
especially true since this is on the return trip in ballast
and the machinery will only run about 48 hours each trip.
Nevertheless, again for extreme conservation, a 300 KW
generator has been included.
To make a usefully indicative estimate of operating costs,
the following assumptions were made:
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The tanker will operate
to 360 days per year. |
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Six (6) voyages per year
between Persian Gulf and USA. |
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Half of the voyages are
return trips in ballast, or 6 trips a year. |
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Assume the 2 compressors
and blower must operate 48 hours to obtain hypoxia
and carbonation in all 8 tanks (note that actually
the cfm of both compressors is only required for
tanks B3 port and starboard and B6 port and starboard. |
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Operating costs are primarily
the fuel costs for the inert gas generator and the
300 KW generator. |
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n is 5 years (economic
payback period) and i (interest rate) is 8%. |
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If the gas and electric
generators operate 48 hours for each of 6 voyages, then
the total operating time is 288 hours per year for each
generator. About 6,000 gallons of diesel fuel would be
consumed by the electric generator and for the gas generator
about 16,500 gallons. This is a total of 22,500 gallons.
At a cost $1.25 per gallon, the yearly operating cost
will be about $28,125. Considering the few hours per year
that the machinery operates and the fact that the ship
has no cargo and therefore less requirements of the crew,
minimal cost has been allocated for maintenance.
Therefore: |
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| In estimating the
cost of treatment per ton of ballast water, the estimated
annual operating costs of $28,125 is used. The approximate
4 million cubic feet of ballast is 128,000 tons. Six trips
are made in ballast, which is a total of 768,000 tons
treated. Therefore, cost of ballast water treatment is
3.7 cents per ton. |
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