Recently, the temperature difference between day and night is very large, like 10 degrees. What if, we have a heat tank that store the hot air on the day, and release the hot air at night to generate electricity?
I roughly sketched the idea. And the P-T plot is not correct.
An improved version could be a liquid with boiling point like 20 degrees. This tank of liquid will put inside the heat tank. On the day, let the hot air flow and heat up the liquid. A pressure is building up in the tank. At evening, close the heat tank, and insulate it. The hot air in the heat tank can be a buffer for the heat loss. There is another empty liquid tank outside and it is connected with the liquid tank inside with a tube. A turbine is inside the tube. When the temperature dropped at night. the tube was open and the hot gas flow from the liquid tank to release the pressure. This generate electricity. The hot gas meet the cold outdoor liquid tank will cold down and condense. When the sun goes up, the condensed liquid will flow back to the indoor liquid tank and a cycle complete.
In the future, thanks to the global warming, the temperature difference will be larger, and this new energy source harvest the energy in the atmosphere.
An extreme of this heat engine is using the temperature difference between root-top and the basement. Is it as same as the water heating solar panel?