the example of energy use on page 31, leading to equation (2.1), consider a family (two people) who use gasoline at the rate indicated but who heat their home electrically in accordance with the efficiencies given in the text above equation (2.1). How would this affect the per person power consumption?

Question

Quizplus · Accepted Answer

The Answer is Assuming an efficiency of 40% for electricity generation the primary energy use for two people will be gasoline

9.8 imes 10 ^ { 10 } \mathrm {~J}

heating

( 1 / 0.4 ) imes \left( 1.04 imes 10 ^ { 11 } \mathrm {~J} ight) = 2.6 imes 10 ^ { 11 } \mathrm {~J}

electricity (non-heating)

( 1 / 0.4 ) imes \left( 4.32 imes 10 ^ { 10 } \mathrm {~J} ight) = 1.1 imes 10 ^ { 11 } \mathrm {~J}

Therefore the per capita primary power consumption will be

0.5 imes \frac { ( 0.98 + 2.6 + 1.1 ) imes 10 ^ { 11 } \mathrm {~J} } { 3.15 imes 10 ^ { 7 } \mathrm {~s} / \mathrm { y } } = 7.4 \mathrm {~kW}

compared to

5.0 \mathrm {~kW}

for oil heating.

The Example of Energy Use on Page 31, Leading to Equation