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Battery Questions and Answers

Written by William C. Shumay Jr. for Arcon Equipment Inc., published in the Material Handling Wholesaler
copyright © William C. Shumay Jr.
For more articles, please visit http://www.arconequipment.com

The Fuel Cell: Advanced Vehicle Power

Last month I introduced the Horizon advanced lead-acid battery, and as you may recall, one of its strong points (especially for consumer highway vehicles) was its phenomenally rapid recharge cycle: less than 30 minutes. This is fast turn-around for an electric vehicle power pack, but there may soon be a faster way: Use a fuel cell and fill up the fuel tank when you run low.

A fuel cell is an electrochemical cell, as is a conventional battery. The difference is that instead of recovering and restoring the original composition of its reactants by charging with electricity, the fuel cell "uses up" the fuel you provide and emits reaction byproducts– one of which happens to be electricity.

Fuel cells can be sized to provide the same electrical power output as a conventional battery, operate the same types of electric motors, and work through the same basic control system. It is not far-fetched to imagine a manufacturer someday offering the option of either a fuel cell or battery power pack for the same electric vehicle. And it may even be a reasonable aftermarket alternative. The user of such a "convertible" electric vehicle may opt to make the switch based on the price of fuel vs. local utility electrical costs, or the relative up-front or life-cycle costs of the hardware.

One disadvantage of the fuel cell compared to a conventional battery: proposed designs do not accommodate energy recovery through regenerative braking. A battery-powered vehicle can be designed to use its electric motors as braking generators, charging the battery a little with every touch of the brake pedal, ultimately gaining back as much as 30% of the expended electrical energy.

Under today’s technology, it is expected that an electric vehicle fuel cell would wear out no more quickly than the most long-lived battery, and potentially it might operate fully as long as the vehicle itself. Many of the same fuels used in internal combustion (IC) engines have been used to feed fuel cells, but the most practical, room-temperature cells envisioned for consumer vehicles use pure hydrogen along with air (the oxygen source). If natural gas or methanol is used as a feed stock for such a room-temperature fuel cell, it must first be "reformed" in a primary stage in order to strip out the hydrogen. In the process, carbon dioxide is vented to the atmosphere.

The hydrogen-oxygen reaction inside the fuel cell itself is clean and efficient: the byproducts are electricity and water. Electrical energy can be produced at an efficiency approaching 70% with some fuel cell designs, but this drops if a reformer stage must be used to provide pure hydrogen. Looking at the overall system efficiency of an electric vehicle with fuel cell vs. an IC engine-powered car, the electric is three times better at turning chemistry into motion.

The environmental impact of fuel handling emissions, storage, spillage, and distribution remain issues of some concern with fuel cells just as they are with every available IC engine technology. If a hydrocarbon is used, greenhouse gases such as raw fuel vapors and carbon dioxide are inevitably released to the atmosphere, but the fuel cell has two points in its favor as a "fuel burning" powerplant: 1) It is more efficient than an IC engine, so the volume of wastes produced per mile is correspondingly less 2) Nitrous oxide emission, a major degrader of air quality, is not a problem with fuel cells.

Like the advanced battery technologies proposed for electric highway vehicles, the fuel cell is a maintenance-free powerplant. At its energy-producing core, the fuel cell has no moving parts to adjust, tinker with, or tune up. Naturally, this is a significant advantage over the IC engine. The electric motors and associated control system in state of the art vehicle designs are also long lived and mechanically simple.

A new public information and education program by the Electric Power Research Institute (EPRI) and a group of electric utility companies is designed to help pave the way for public acceptance of electric highway vehicles.

The Electric Vehicle Research Network (EVRN), as the project is called, will send an electric vehicle demonstration exhibit across the country, as well as establish permanent exhibits such as one that opened October 30th at the SciTrek museum in Atlanta. The SciTrek exhibit includes a working R&D facility that allows people to view actual tests on electric vehicle servicing procedures.

For more information, contact Arcon Equipment Inc. (440) 232-1422.

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