Hawaii has about 1200 km of coast line and a population of about 1.4 million.
(a) If Hawaii's per capita energy consumption is similar to the rest of the United States, calculate the total annual primary energy use in this state.
(b) Compare the results from part (a) with the total annual wave energy available in Hawaii. What fraction of the total wave energy would satisfy the primary energy needs?

Question

Quizplus · Accepted Answer

The Answer is (a) From Table 2.1 the per capita average power consumption in the United States is

11,730 \mathrm {~W}

. Per year this represents

( 11,730 \mathrm {~J} / \mathrm { s } ) imes \left( 3.15 imes 10 ^ { 7 } \mathrm {~s} / \mathrm { y } ight) = 3.69 imes 10 ^ { 11 } \mathrm {~J} / \mathrm { y }

For the state of Hawaii the total annual energy use is

\left( 1.4 imes 10 ^ { 6 } ight) imes \left( 3.69 imes 10 ^ { 11 } \mathrm {~J} ight) = 5.17 imes 10 ^ { 17 } \mathrm {~J}

(b) From the map the average wave power in Hawaii is

100 \mathrm {~kW} / \mathrm { m }

. For the entire state this represents

\left( 1.0 imes 10 ^ { 5 } \mathrm {~W} / \mathrm { m } ight) imes ( 1000 \mathrm {~m} / \mathrm { km } ) imes ( 1200 \mathrm {~km} ) = 1.2 imes 10 ^ { 11 } \mathrm {~W}

This represents an annual energy of

\left( 1.2 imes 10 ^ { 11 } \mathrm {~J} / \mathrm { s } ight) imes \left( 3.15 imes 10 ^ { 7 } \mathrm {~s} / \mathrm { y } ight) = 3.78 imes 10 ^ { 18 } \mathrm {~J} / \mathrm { y }

Compared to the annual energy use this is

\left( 3.78 imes 10 ^ { 18 } \mathrm {~J} / \mathrm { y } ight) / \left( 5.17 imes 10 ^ { 17 } \mathrm {~J} / \mathrm { y } ight) = 7.3 ext { times as much }

Hawaii Has About 1200 Km of Coast Line and a Population