New Technology Increases Efficiency in Hydrogen Fuel-Cell Cars

.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:”"; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:”Times New Roman”; mso-fareast-font-family:SimSun;} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} –> The process, called hydrothermolysis, uses a powdered material called ammonia borane, which
contains one of the highest hydrogen contents of all solid materials.
The ammonia borane contains 19.6 percent hydrogen, which is one of the highest hydrogen contents of all solid materials, that means a relatively small quantity and volume of the material are needed to store large amounts of hydrogen.

In hydrolysis, water is combined with ammonia borane and the process requires a catalyst to generate hydrogen, while in thermolysis the material must be heated to more than 170 degrees Celsius, or more than 330 degrees Fahrenheit, to release sufficient quantities of hydrogen. Currently hydrogen fuel cells run at a temperature of 85 degrees Celcius (185 degrees Fahrenheit) and require high pressures to function.

At the optimum conditions, hydrogen from the hydrothermolysis approach amounted to about 14 percent of the total weight of the ammonia borane and water used in the process. This is significantly higher than the hydrogen yields from other experimental systems.

"This is important because the U.S. Department of Energy has set a 2015 target of 5.5 weight percent hydrogen for hydrogen storage systems, meaning available hydrogen should be at least 5.5 percent of a system’s total weight," Varma said. "If you’re only yielding, say, 7 percent hydrogen from the material, you’re not going to make this 5.5 percent requirement once you consider the combined weight of the entire system, which includes the reactor, tubing, the ammonia borane, water, valves and other required equipment."

The concept has been proved and the only missing link in the system is how to recycle the ammonia borane used in the reaction and return it to its original state so that it doesn’t create waste. Researchers believe that this system would be able to fuel vehicles as well as small appliances.

[source: Science Daily, PDF download for more information]

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