I don't know who would fund pumping megawatts into space in the form of laser but there would be some thermal emissions in air being heated by the beam, the transmitter itself would have thermal emissions, and then the never ending, meddlesome government/market forces who would see regulation/profit in your system.
But generally, I am probably not the best one to answer this. If you take energy, convert it to power of any form, groups will try in some form to take control of it. Eventually your idea would be converted into a system to generate electricty. Then we get into all kinds of problems. Conversion of (whatever) into electricty (there has to the a thermal transfer in the conversion), send it down wires (resistance of materials over long distance is also a very small thermal emmission), and then allow whoever to use that power - you result with more thermal emissions - if the person uses your wind converted power to run their home air conditioner, you probably are pumping more heat into the biosphere than you are taking out.
Each conversion gives off thermal emissions and the final product of your power certainly will give off heat in some form. Even if it is just to power up high watt lasers, some heat would be leaked off in the process and the area where the beams were being fired off would change temps throughout the atmospheric layers unless it were of a specific wavelenght that is completely transparent to Nitrogen, Oxygen, Carbon, Hydrogen, and any other gas it might encounter.
It this wrong?
