One very important consideration when purchasing a new or used forklift truck is deciding on the type of propulsion system required. With today's technology, that means either going electric utilizing lead acid batteries or internal combustion using fossil fuels such as LPG, gasoline or diesel. Hydrogen fuel cells and compressed natural gas are emerging technologies that can be given credence in the near future. They are not part of this comparison due to the extra requirements needed for fueling stations and the extra costs associated with being emerging technologies until they gain popularity and support.

If load capacity and lift height specifications are equal, the most common rationale is an electric lift truck is used indoors while an internal combustion lift truck is more advantageous for outdoor use. The logic being electric forklifts have little or zero emissions during operation making them more suitable for indoor material handling. However, making an electric forklift suitable for outdoor use in wet weather necessitates additional seals and waterproofing of components that increases manufacturing costs and makes battery changing more difficult and time consuming. Also, electric forklifts typically have cushion tires which are only useful on prepared hard surfaces such as concrete.

The benefits of an internal combustion forklift are higher load capacities (if needed) and the ability to be used outdoors without additional weatherproofing. Internal combustion lift trucks also have the advantage of quick refueling (typically under 5 minutes). Internal combustion forklifts using LPG can be used indoors with proper ventilation and periodic mechanical maintenance to reduce emissions. They cannot be used in or near controlled atmosphere rooms or in cold storage warehousing due to little or no ventilation provisions. Carbon monoxide exposure is a serious and expensive health risk for the personnel of a company. Electric forklifts are virtually emission free and provide a cleaner indoor environment. They can be used indoors in and near cold storage and controlled atmosphere rooms. Electrics can also be used in food processing areas. Internal combustion forklifts can have a vacuum cleaner effect by sucking dust and dirt from ground level and then expelling those particulates out the rear of the machine through the radiator. This can have an accumulative soot effect on items stored in a warehouse for any prolonged period of time.

Electric battery propelled lift trucks are limited by the state of charge of the battery. When maintained properly, a fully charged battery will provide five to six hours of constant use or the equivalent of an eight hour shift with operator breaks. Forklift performance will degrade as the battery reaches 80% discharge (any further discharge will result in damage to the battery). Newer technology such as regenerative braking and AC motors is increasing battery life. The downside to electric forklifts is the battery requires an eight hour charge cycle followed by an eight hour cool down cycle before it can be used for another eight hour shift. If the forklift is expected to be used for two or three shifts each day then an additional battery is needed for each of the additional shifts. There is also the time needed to swap out batteries which is usually 10 to 45 minutes. These are considerable expenses that need to be factored into the total cost of ownership when comparing electric to internal combustion lift trucks. Also, the square footage needed to accommodate a battery charging station area is approximately 200 square feet plus the requirements the area needs to be dry, ventilated and temperature controlled . However, fossil fueled equipment also needs additional space allocated for secure LPG tank storage and gasoline or diesel fuel storage which meets EPA requirements. Depending on load capacity size, an internal combustion forklift may only need one LPG tank to make it through an eight hour shift.

Internal combustion forklifts typically have a ten to twenty percent price advantage over equivalent electric forklifts when load capacity is under 6000 lbs. Electric forklift pricing increases substantially over internal combustion units when load capacity over 6000 lbs. is needed. Additional costs for electric forklifts are the extra batteries needed for operating more than one eight hour shift per twenty four hour period.

However, when total cost of ownership is considered, electric forklifts will be less expensive than internal combustion forklifts to operate and maintain. Internal combustion lift trucks require more frequent scheduled maintenance and also require more consumable parts (tires, emissions maintenance, oil and filter changes). Electric forklifts (especially AC powered versus DC powered) are more simplistic mechanically (no transmissions, torque converters, etc.) than internal combustion forklifts. Where electric battery propelled forklifts really excel is in fuel costs. At a national typical average costs of ten cents per kilowatt/hour for charging batteries, most electric forklifts cost approximately $0.75 per hour to operate for "fuel". Internal combustion forklifts using LPG average approximate costs of $1.90 to $2.00 per hour to operate. The more hours run per day, the savings of electric forklifts begins to add up quickly.