Study on Renewable Energy Resources, Oman - authority for ...

Renewable Energy Resources in Oman
Fig. 6.1 Long-run marginal costs for conventional technologies (two annual full load
hours scenarios) - Low Gas Price
USD/MWh
90
80
70
60
50
40
30
20
10
0
GT 140MW CCGT 400MW HFO 300MW Coal 1000MW
5000
Hours
7500
Hours
The assumed number of annual full load hours influences long-run marginal
costs. Increasing the assumed number of full load hours per year from 5000 to
7500, acts to reduce the long-run marginal cost per unit.
The long-run costs of the gas turbine are least sensitive towards number of full
load hours because this technology has the lowest specific investment costs. If
the annual number of full load hours was decreased to below approximately 2000
hours, the long-run costs for the gas turbines would be lower than for the combined
cycle plants. This is one reason why gas turbines are suitable as peak load
units with only few operational hours per year.
The tables 6.2 and 6.3 below show the short- and long-run marginal costs, if fuel
prices were 3 USD per MMBtu and 6 USD per MMBtu. The low gas price (1.5
USD per MMBtu) corresponds to the price currently charged the power plants,
i.e. actual cost, not economic costs. Economic costs are assumed to be 3
USD/MMBtu with a depletion premium of 3% p.a. Table 6.2 shows the marginal
cost with a natural gas price of 3 USD/MMBtu and Table 6.3 the cost with a
natural gas price of 6 USD/MMBtu.
Table 6.2 Assumptions and calculation of short- and long-term marginal costs, USD
/MWh -( medium gas price 1190 US c/Gcal)
Gas turbine,
140 MW
Combined
Cycle,
400 MW
HFO
Steam,
300 MW
Coal
Steam,
1000 MW
Fuel costs, US c/Gcal 1190 1190 2519 880
Short run marginal costs, USD/MWh 30.73 21.86 57.50 19.97
Long run marginal costs, USD/MWh
(5.000 h)
Long run marginal costs, USD/MWh
(7.500 h)
42.66 32.67 82.33 51.59
38.68 29.06 74.05 41.05
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