Ammonia Fuels Research Articles

Ammonia fuel cell using doped barium cerate proton conducting solid electrolytes

Proton-conducting solid electrolytes composed of gadolinium-doped barium cerate (BCG) or gadolinium and praseodymium-doped barium cerate (BCGP) were tested in an intermediate-temperature fuel cell in which hydrogen or ammonia was directly fed. At 700 °C, BCG electrolytes with porous platinum electrodes showed essentially no loss in performance in pure hydrogen. Under direct ammonia at 700 °C, power densities were only slightly lower compared to pure hydrogen feed, yielding an optimal value of 25 mW cm −2 at a current density of 50 mA cm −2. This marginal difference can be attributed to a lower partial pressure of hydrogen caused by the production of nitrogen when ammonia is decomposed at the anode. A comparative test using BCGP electrolyte showed that the doubly doped barium cerate electrolyte performed better than BCG electrolyte. Overall fuel cell performance characteristics were enhanced by approximately 40% under either hydrogen or ammonia fuels using BCGP electrolyte. At 700 °C using direct ammonia feed, power density reached 35 mW cm −2 at a current density of approximately 75 mA cm −2. Minimal loss of performance was noted over approximately 100 h on-stream in alternating hydrogen/ammonia fuels.

A study on the combustion of alternative fuels in spark-ignition engines

Theoretical and experimental studies have shown that spark-ignition engine fuel composition can have an influence on performance and exhaust emissions. Studies have been made on gasoline, alcohol, hydrogen and ammonia fuels. Energy content and carbon to hydrogen ratio both are influential in determining engine performance and exhaust content of potential air pollutants exhausted into the atmosphere. Neither hydrogen nor ammonia can produce carbon monoxide or unburned hydrocarbon and theoretically should also give less nitric oxide, at most conditions than do octane and alcohols fuels. Some possible measurements are made using gasoline, methanol and ethanol fuels. These measurements show that there is an increase in engine thermal efficiency and less nitric oxide and carbon monoxide when using methanol and ethanol fuels than that of gasoline. These experiments confirm the theoretical results obtained.

Is Hydrogen the Fuel of the Future?

Shrinking fossil-fuel resources and rising environmental concerns have made imperative, as all the world must now be aware, the development of new power sources. Alternatives such as nuclear, hydroelectric, solar, geothermal, tidal and meteorological power will all be used to a greater extent to produce electricity. But they can also be used to produce nonfossil chemical fuels. One such fuel, hydrogen, is being examined with increasing interest as a possible major fuel of the future. The primary use of nuclear reactors is to generate electricity. This electrical power could be used to electrolytically decompose water to hydrogen and oxygen. The hydrogen could be used as a primary source of fuel or could be converted to a number of other fuels including ammonia, methanol, methane, hydrazine, acetylene and other hydrocarbon fuels. The by-product oxygen could be used in many ways. Some suggest it be used for gasification of coal or in a basic oxygen furnace for the production of steel. Depending on this utilization of oxygen and the cost of electrical power from large nuclear reactors, this system will become economically competitive as the cost of fossil fuels increases. The Common Market's Joint Research Center, for instance, sees hydrogen as a suitable fuel of the future. Euratom scientists G. DeBeni and C. Marchetti, speaking for the research center, claim that electricity, the usual form of marketing nuclear energy, will meet only 10 percent of the energy needs for a technologically developing society. Hydrogen, they feel, could penetrate the remaining 90 percent of that market. They are attempting to produce hydrogen, not by electrolysis, but by using the heat from a hightemperature gas reactor to crack water directly. In a closed system, hydrogen would be produced from water by a heated chemical reaction. This method, says Marchetti, is more direct than the steam-electricity-electrolysis process. A pilot plant, probably in Ispra, Italy, could be in operation within two years, he says. With the present technology it would run at 40 to 50 percent efficiency. Electrolysis under pressure can operate at up to 85 percent efficiency. William C. Gough and Bernard J. Eastlund of the Atomic Energy Commission, who two years ago proposed using plasma leakage from a thermonuclear fusion reactor to reduce trash to its chemical elements (SN: 3/7/70, p. 249), now suggest using ultraviolet light generated by this plasma to dissociate hydrogen and oxygen from water. Another method of hydrogen production utilizes solar energy. William J. D. Escher of Escher Technology Associates in St. Johns, Mich., says an