Concerning Global warming; Can we cool atmosphere by converting it's heat content to electricity? if we do so is it became a perpetual machine in 2nd degree or not? I'm not so good in thermodynamics. But I'm sure it will not violate 1. rule energy is not created from noting, energy converted from one form to another. But not sure with 2. rule. Honestly, I did not understood well this axiom. "heat always flows spontaneously from hotter to colder bodies, and never the reverse, unless external work is performed on the system" OK no objection. Heat pumps uses energy to pump heat from colder bodies to hotter bodies. no confliction.but "total entropy of an isolated system can only increase over time. It can remain constant in ideal cases where the system is in a steady state (equilibrium) or undergoing a reversible process." is not clear since if heat will flow from hotter region to cooler region this axiom is ok for cooler region but entropy will reduced in hotter region. it is confusing me. No arrangement can go beyond Carnot's upper limit to the efficiency of conversion of heat to work in a heat engine. Is it applicable for heat pumps? (As my knowledge, heat pumps is working in reverse Carnot cycle). Heat engines may be bound by efficiency, but again with my knowledge Heat pumps defined by C.O.P. values that defines how much energy transferred from colder region to hotter region with a unit of energy. (typically 1:3) If we transfer 3 unit of energy with 1 unit energy and operate heat pump in hotter region. The net energy insert in hotter region is 4 times of energy needed to heat pump. Heat flow (energy) is a through variable. Total of through variables entering a node must be zero indicating at least one of the through variable must exit from node. Then we can drive out 4 unit of energy from hotter region. If we feed back 1 unit energy to operate heat pump and loose 1 unit in conversion time we can draw 2 unit energy. if we look the picture again, we will see an apparatus consuming no fuel or visible energy producing energy those type machines named as perpetual machine (at least 2nd degree) But I could not pointing violated rules. Can any one point which rule is violated? or this system is not perpetual?