Located in kettle falls, washington, the kettle falls generating station began operation in
1983. the 47.0 mw power plant generates electricity via a rankine steam cycle fueled by
direct combustion of wood waste from an adjacent mill. assume the wood waste has 30.0%
moisture content and 5.0% ash, as-received and that based on life cycle analysis the wood
waste is 50.0% carbon neutral (e. g., when land use changes, harvesting, and carbon uptake
by the wood are considered, the net co2 emissions are 50.0% of the direct or gross co2
emissions from combustion of the switchgrass).
the system has an efficiency of 26.0% and a capacity factor of 91.0%. during periods of high
demand, the plant supplements its electricity generation with an 7.0 mw natural gas turbine
with a heat rate of 8000 btu/kwh. assume the plant supplies electrical power to 43,500
homes, each using 9,000 kwh of electricity annually. the natural gas is 80.0% methane (ch4),
10.0% ethane (c2h6), 5.0% carbon dioxide (co2), and 5.0% nitrogen (n2) by volume. the wood
waste and natural gas have higher heating values of 12.8 mj/kg (as-received) and 48.3 mj/kg,
respectively. neglect transmission losses. the ultimate composition of the dry, ash-free wood
waste is given in the table below.

ultimate composition (wt% dry ash-free)

c 50.0%

h 6.0%

o 44.0%

a. how much electricity does the wood-fired portion of the kettle falls generating station
generate each year (mwh/y)? answer 374665