The Fuel Cell-Research Probes Vast New Market for Petroleum Products
Authors: Schultz E.B. 
Published: December 2007

Introduction

Research and development in the field of fuel cells have been expanding, especially in the last 10 years, and each symposium on the subject brings still more information to be considered. Developments are coming from a number of industries-petroleum, gas, automotive, chemical, battery, electronic and electric to provide specialized cells for the diversified requirements of civilian, military and space applications. The purpose of this paper is to provide some insight into the trends now taking shape which might affect the utilization of natural gas, petroleum fractions and their derivatives e.g., hydrogen, partially oxygenated hydrocarbons and nitrogen compounds in fuel cells of many types. Emphasis is on research because it is difficult to develop meaningful economic analyses at this early stage. Fuels, chemicals and waste-gas streams produced by the gas, oil and petrochemical industries might be used in fuel cells for such applications as large- or small-scale power generation, vehicular power plants, secondary power in space craft and in various military applications. High theoretical and practical efficiencies usually are the most attractive characteristics of fuel cells, although in military and other applications special requirements of fuel logistics, power density, radio and radar silence, and lack of noise may exist. Since the fuel cell does not involve high-speed rotary motion, in contrast to conventional engine-generator systems, audible noise and electronic interference can be avoided. The fuel cell, since it is not a heat engine, offers the possibility of operation at low temperatures with sufficiently reactive fuels, thus eliminating heat-recovery and warm-up problems and avoiding detection by infrared means. Fuel-cell fuels that are products of the gas, oil and petrochemical industries enjoy a preferred cost position, of course, which is one important reason why they are receiving so much research attention. This is illustrated by the recently presented fuel cost data shown in Table 1.All of the fuel-cell devices to be considered herein convert chemical energy to electrical energy through electrochemical reactions. Conventional dry cells and batteries also do this. However, fuel cells are outstandingly different in that liquid and gaseous fuels and oxidants are normally used, together with ideally inert electrodes, permitting the cell to be fed continuously. Conventional dry cells and storage batteries customarily use solid (consumable) oxidants and solid "fuels" (chemical reductants).Exceptions to these rules are known. Some cells combine a solid consumable-fuel electrode with an air electrode (inert and continuously fed with air), but these are still referred to as types of fuel cells. All fuel cells have the three essentials of any electrolytic cell the cathode or oxidant electrode, the anode or fuel (reductant) electrode, and the electrolyte located between anode and cathode. Current may be conducted through the electrolyte by cations or anions, as shown in Figs. 1 and 2. In practice, the hydrogen ion is the only cation and hydroxide, carbonate and oxide ions are the only anions being utilized in the various true fuel cells under development.

Difficulties in Using Hydrocarbon Fuels

In Low-Temperature Fuel Cells

Recently increased activity on utilization of hydrocarbons as fuel-cell fuels has not yet revealed any simple means for achieving high performance without applying high temperatures. In the Allis-Chalmers fuel-cell tractor, initially thought to have consumed propane at about 60 degrees C, it now appears that all or a major part of the electrical energy was produced from the hydrogen mixed with the propane. Total recycle tests on such mixtures were described by U. S. Signal Corps investigators; hydrogen was consumed preferentially and propane remained essentially as an inert. More recent data on hydrocarbon cells at low temperatures have been given by Schlatter.

TABLE 1-FUEL COST DATA

Cost at 100% Efficiency Fuel (mils/kw-hr) Zinc 200 Sodium 110 Hydrogen 35 Methanol 17 Ammonia 10 Synthesis gas 7 Gasoline 4 Diesel oil 2.5 Propane 3 Methane 2.4

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