Hi Luis

Your questions are fundamentaly idealistic in nature.

#1 If you are using the Lift Truck indooors for one minuite of its life the answer is simple, it must be ELECTRIC. Machines are replaceable humans are not. In Nova Scotia our law states that any ICE vehicle operated within an enclosed space must have the vehicle or the area monitored at all times for carbon monoxide emmisions.

#2 Google Raymond Corporation and you will find many space and unit calculators as well as an in depth look into the modern materials handling world.

#3 Your request for cost per hour calculations has to many variables to be realistic. Assuming you have the same operator on both vehicles operating the sane tasks it will be very simple to calculate the cost per pound of propane. On the other hand the cost of calculating electricity is verry difficult. $per killowatt hour comes from your electric company. Calculating the killowatt hours used will depend on depth of discharge, efficiency of charger, general maintainance of battery (cleaning & watering), type of charger purchased, age of battery and what voltage charger you have purchased(for example using a single phase 110 volt charger to charge a battery will probably cost you 300% more per year to charge your battery as apposed to using a 600 volt three phase charger). Your power company may have you on a variable price rate depending on consumption and peak usage may drive your monthly bill higher.

Although this is not a direct answer to your questions I do hope it gives you some points to ponder.