I need intelligent answers for this question and please do include your reference
D`Arcy's formula applies to flow-induced pressure drop. For a vertical pipe, gravity-induced pressure change can also be important, if the pipe is carrying liquid. In most practical situations the gravity effect is negligible for gases.
Gas is more cost effective. Eco friendly is probably electric but that depends on how the power company makes the electricity IE. Nuclear/Coal/Hydro I have found that gas dryers are quicker to dry clothes and have less service issues. Gas dryers have many safety features to prevent problems. All have electronic ignition now so there is no more pilot light. Go gas. They might be slightly more expensive but they are just all around better.
