A town is considering using its lake as a source of power. The average temperature difference from the top to the bottom is 15°C, and the average surface temperature is 22°C. (a) Assuming that the town can set up a reversible engine using the surface and bottom of the lake as heat reservoirs, what would be its efficiency?
(b) If the town needs about 1.0 × 108 W of power to be supplied by the lake, how many m 3 of water does the heat engine use per second?
(c) The surface area of the lake is 8.0 × 107 m2 and the average incident intensity (over 24 h) of the sunlight is 200 W/m2. Can the lake supply enough heat to meet the town's energy needs with this method?