1 million people use energy at the rate of 10GW. The city occupies a circular area 15km in diameter. The top km of Earth’s crust consists of granite (density 2,700 kg/m3and specific heat 840J/kg/K, and thermal conductivity 3.37 W/m*K) and that the avg temp in this layer is 60°C higher than the surface temp
Est. the total energy that could be extracted in cooling the 1km thick layer of crust beneath the city to the temp of the surface
The efficiency in converting this low-quality thermal energy to useful energy is 5%, how long would the resource 1km below the city last

Question

1 million people use energy at the rate of 10GW. The city occupies a circular area 15km in diameter. The top km of Earth’s crust consists of granite (density 2,700 kg/m3and specific heat 840J/kg/K, and thermal conductivity 3.37 W/m*K) and that the avg temp in this layer is 60°C higher than the surface temp
Est. the total energy that could be extracted in cooling the 1km thick layer of crust beneath the city to the temp of the surface
The efficiency in converting this low-quality thermal energy to useful energy is 5%, how long would the resource 1km below the city last