But, unfortunately, that is not the whole story. The electricity used to power the vehicle had to be generated somewhere. If it was generated at a power plant that used a combustion process (rather than nuclear, hydroelectric, solar or wind), then only about 40% of the fuel required by the power plant was converted into electricity. The process of charging the batteries requires the conversion of alternating current (AC) power to direct current (DC) power. This process has an efficiency factor of about 90%.

So, if we look at the whole cycle, the efficiency of an electric battery powered vehicle is 72%, the coal or gas fired power generating plant is 40%, and then 90% for recharging the battery. That produces an overall efficiency factor of 26 percent (though of course, only part of this inefficiency i seen by the using company directly).

If the electricity for the vehicle is generated by a hydroelectric dam, then it is basically free (no fuel was used to generate it), and the efficiency of the electric vehicle jumps to about 65 percent. However, major hydroelectric dams in the United States are found only in the Northwest, the Tennessee Valley, and on the Colorado River and produce only about 12% of the total electricity consumed in the country.

Fuel Cell Powered Vehicle Efficiency Factors

The most important feature of the fuel cell is that when powered with pure hydrogen, it has the potential to be up to 80% efficient. That is, it converts 80% of the energy content of the hydrogen into electrical energy. However, we still need to convert the electrical energy into mechanical work. This is accomplished by the electric motor and inverter. A reasonable number for the efficiency factor of the motor/inverter is about 80%. So we have 80% efficiency in generating electricity, and 80% efficiency converting it to mechanical power. That yields an overall efficiency factor of about 64 percent.

So to summarize: with gasoline powered vehicles at *20% efficiency, and battery powered vehicles at *26%, that makes the *64% efficiency of fuel cell powered vehicles very interesting in comparison. Another way to look at this is:

for every $100 spent on fuel for a gasoline powered vehicle - $80 are lost

for every $100 spent on a kilowatt of electricity for recharging the battery of an electric powered vehicle - $76 are lost

and, for every $100 spent on hydrogen to refuel the fuel cell powered vehicle - $36 are lost.

It must be pointed out that the above “cradle to grave” efficiencies are somewhat inconsistent. While gasoline and hydrogen based efficiencies are considered at the pump with no consideration for generation and transportation of the fuel, the electric efficiencies are calculated including generation of electric power at the power plant. In order to make the above comparisons more accurate, production and transportation costs for gasoline and hydrogen would have to be factored in.

A facility using fuel cell technology will need storage tanks of hydrogen fuel on-site. The company then purchases a supply of hydrogen fuel from a commercial dealer. Some large users may decide to have their own on-site hydrogen generation, storage, and dispensing capability. Depending on amount of fuel usage, the cost per kilogram for generating your own hydrogen can be half to two-thirds the delivery cost from a commercial dealer.

Of course there are many other factors to take into consideration such as, the initial cost of the vehicle and supporting systems, available and cost of the fuel supply, and operational comparisons.

The Polymer Electrolyte Membrane Fuel Cell (PEMFC)

If you want to be technical about it, a fuel cell is an electrochemical energy conversion device. A fuel cell converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity.

The common lead-acid battery, which we are all familiar with and as mentioned above, is also an electrochemical device. A battery has all of its chemicals stored inside, and it converts those chemicals into electricity. This means that a battery eventually "goes dead" and you either replace it or recharge it.

With a fuel cell, chemicals constantly flow into the cell so it never goes dead - as long as there is a flow of chemicals into the cell, the electricity flows out of the cell. Most fuel cells in use today use hydrogen and oxygen as the chemicals. The PEMFC uses one of the simplest reactions of any fuel cell.

The Department of Energy (DOE) is focusing on the PEMFC as the most likely candidate for transportation applications. The PEMFC has a high power density and a relatively low operating temperature (ranging from 60 to 80 degrees Celsius, or 140 to 176 degrees Fahrenheit). The low operating temperature means that it doesn't take very long for the fuel cell to warm up and begin generating electricity, thereby, making the PEMFC one of the most promising fuel cell technologies. This type of fuel cell will probably end up powering cars, buses, and trucks and maybe even our houses someday.

As it relates to environmental issues – while PEM fuel cells are not causing any pollution, as the output is electric power, heat and water, the generation of Hydrogen is not entirely pollution free. In that regard, the fuel cell is not really that different from purely electric batteries where most of the battery material is recycled.

How PEMFC Technology Benefits DC Operations

PEMFC vehicles provide quick and easy refueling thereby maintaining consistent performance levels throughout the work shift while operating at a relatively high fuel consumption efficiency factor without causing pollution.

In operation, the PEM fuel cell provides a regular supply of clean electric power to operate the vehicle and, at the same time recharges the on-board “peaking batteries” which are used for auxiliary power when demand exceeds that which the fuel cells can provide, i.e., lifting maximum weight loads.

The lift truck contains a fuel tank filled with compressed hydrogen gas or liquid hydrogen which is typically delivered to the facility via tanker truck. A control panel mounted on the vehicle lets the operator know when the fuel is low and needs to be refilled. Instead of having to remove a 3,000 pound battery for recharging at the end of every shift, the driver can quickly refill the tank with liquid hydrogen at a dispensing station in just a few minutes. Water generated by the system can be collected for reuse or automatically evaporated.

While the fuel cell itself is quiet– in a lift truck they are part of the engine with spinning mechanical components resulting in noise levels that would not be thought of as “quiet” especially when operating at or near maximum capacity.

Although PEM fuel cell powered lift truck technology has shown considerable promise, and most major equipment manufacturers have on-going fuel cell powered development programs with 100s of fuel cell powered lift trucks and pallet jacks in operation in a variety of applications, the main obstacle to widespread deployment of this technology is understanding the price equation, which can be complex as there are several factors to be evaluated.

For more insight on this evolving technology you can watch a video interview that SCDigest Editor & Chief Dan Gilmore recently had with Emst Baumgartner, Program Manager for Crown’s fuel cell program – see “Fuel-Cell Powered Lift Trucks Starting to Make an Impact in Distribution Centers”.

Final Thoughts

It is not likely that fuel cell powered vehicles will replace gasoline, propane, or battery powered in the DC anytime soon. However, the many advantages of fuel cell technology are just beginning to be understood. For example, in addition to their high operating efficiency factor, they have the ability to deliver a steady supply of power throughout the work shift. This is in contrast to traditional battery powered trucks whose voltage drops as the day wears on, making the truck sluggish and less productive. The elimination of “voltage lag” equates to increased productivity (move more pallets) further enhancing the TCO of fuel cell powered trucks.

Perhaps, the biggest benefit to businesses and consumers alike is the ever increasing variety of choices and solutions that are available and the resulting uniqueness it enables.

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