Answer:
Mechanical
94 percent of all school buses in America are powered by diesel engines because of their reliability, durability and safety. Almost half of these (46 percent) rely on the cleanest, near-zero emission diesel engine technology.
Chemical
school bus uses petroleum as chemical potential energy.
Electrical
An electric bus draws electricity from the power grid and stores it in a battery that can be recharged once the electricity has been used up. This basically mirrors the way our electronics work. We plug them in and let the battery charge and then use them wirelessly until it's time to charge again
Thermal
They heat the cold coolant from engine's block to 160° F in as little as one hour, then pump it back to the vehicle's engine and heat exchangers. The result: engine is preheated and the vehicle's heat exchangers distribute an abundance of heat to the vehicle's interior.
