However, fuel cells that will be used in cars operate at about 85 degrees Celsius (185 degrees Fahrenheit). Hydrogen fuel cells generate electricity to run an electric motor.
The new process also promises to harness waste heat from fuel cells to operate the hydrogen generation reactor, Varma said.
The researchers conducted experiments using a reactor vessel operating at the same temperature as fuel cells. The process requires maintaining the reactor at a pressure of less than 200 pounds per square inch, far lower than the 5,000 psi required for current hydrogen-powered test vehicles that use compressed hydrogen gas stored in tanks.
In some experiments, the researchers used water containing a form of hydrogen called deuterium. Using water containing deuterium instead of hydrogen enabled the researchers to trace how much hydrogen is generated from the hydrolysis reaction and how much from the thermolysis reaction, details critical to understanding the process.
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 reported in the scientific literature, Varma said.
"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," he 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."'/>"/>
|Contact: Emil Venere|