Duke Energy Corp. is an integrated energy and energy services provider that generates and distributes electricity in North Carolina and South Carolina. Operating statistics for electricity gen- eration and sales are provided from its public reports for a recent fiscal year, as follows:
Sources of Electric Energy, GWh* Generated-net output:
|
Coal
|
43,696
|
|
Nuclear
|
40,256
|
|
Hydro
|
2,101
|
|
Oil and gas
|
106
|
|
Total generation
|
86,159
|
|
*Gigawatt-hour
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Electric Energy Sales, GWh*:
Residential $23,947
Nonresidential 58,459
Total GWh sales $82,406**
*Gigawatt-hour
**The difference between generation and sales is caused by line losses and purchased power.
The difference between generation and sales is caused by line losses and purchased power.
Duke operated eight coal-fired stations and seven oil and gas combustion turbine stations with a combined capacity of 7,699 MW (megawatts), three nuclear generating stations with a combined net capacity of 5,020 MW, 31 hydroelectric stations with a combined capacity of 2,806 MW, and seven combustion turbine stations with a combined capacity of 2,424 MW.
The megawatt (MW) rating is the capacity of the unit at a point in time. Translating this capacity into annual MWh (megawatt-hours) requires multiplying this amount times 24 hours per day times 340 days in the year (assuming 25 days for repair). A gigawatt is 1,000 megawatts.
a. Determine the utilization of the coal, nuclear, hydro, and oil and gas turbine generation assets. (Hint: You must translate the megawatt rating into gigawatt-hour capacity for 340 days.)
b. Why are the utilization statistics different across the different generating sources?
c. What percent of total electric sales (in GWh) is nonresidential?
d. Why are operating statistics like this useful to analysts?