<[email protected]> wrote:
> ...one can only hope! However the truth is that most of the energy we use > is > returned to the environment as heat, so taking it out as wind power and > putting > it back as heat would probably have very little net effect. > Two things about this are a little off: 1. Nuclear power and fossil fuel combustion add heat to the earth's atmosphere. Solar PV, solar water heating, hydro and wind do not. That is, they add no net heat. They transfer it from one place to another. Hydro, for example, reduces the heat in a river a little, and transfers it to the city where it powers machines. It shows up there as waste heat. All energy ends up as heat. Fossil fuel releases heat to the atmosphere that was collected from the sun eons ago. 2. The heat from energy production does not matter much. It is not the cause of global warming. It leaves the atmosphere in about a half-hour. It is true that urban "heat islands" from large numbers of automobiles are a problem, but it is a separate problem from global warming, which is far more serious. If we derive all of our energy from conventional nuclear power or cold fusion we would still be heating the atmosphere at about the same rate we do today, because cold fusion cars will probably not have hugely better Carnot efficiency than today's models. If we get our energy from solar, wind or even biofuel this will reduce short term atmospheric heating somewhat. To get a sense of how much biofuel production reduces local heat . . . step into a forest. It is a lot cooler than an open field, isn't it? All that heat is being absorbed by the leaves, or reflected back into space I suppose. Not much reflects from the trees to the fields. - Jed
