Using information from Figure 16.9 and an energy content of MSW of 10 MJ/kg, estimate the number of 35% efficient 1000 MWe coal-fired power plants that could be eliminated if 50% of MSW were burned to produce electricity.

Question

Quizplus · Accepted Answer

The Answer is From Figure 16.9 the total MSW (in the U.S.) in recent years has been about

250 imes 10 ^ { 6 }

tons per year, this is

2.27 imes 10 ^ { 11 } \mathrm {~kg} / \mathrm { y }

. If

50 \%

of this is utilized the energy available is

( 0.5 ) imes \left( 10 ^ { 7 } \mathrm {~J} / \mathrm { kg } ight) imes \left( 2.27 imes 10 ^ { 11 } \mathrm {~kg} / \mathrm { y } ight) = 1.14 imes 10 ^ { 18 } \mathrm {~J} / \mathrm { y }

A

35 \%

efficient

1000 \mathrm { MW } _ { \mathrm { e } }

coal fired generating station actually produces

\left( 1000 \mathrm { MW } _ { \mathrm { e } } ight) / ( 0.35 ) = 2860 \mathrm { MW }

of thermal energy. Assuming a

100 \%

capacity factor this corresponds to

\left( 2.86 imes 10 ^ { 9 } \mathrm {~W} ight) imes \left( 3.15 imes 10 ^ { 7 } \mathrm {~s} / \mathrm { y } ight) = 9.0 imes 10 ^ { 16 } \mathrm {~J} / \mathrm { y }

The energy potential of MSW is, therefore, equivalent to

\left( 1.13 imes 10 ^ { 18 } \mathrm {~J} / \mathrm { y } ight) / \left( 9.0 imes 10 ^ { 16 } \mathrm {~J} / \mathrm { y } ight) = 12.6

or about 13 coal fired generation stations.

Using Information from Figure 16