A new approach to the use of hydrogen to fuel motor vehicles will be undertaken by engineers at the University of California, Riverside who are seeking to develop one of the world's cleanest engines.
The College of Engineering--Center for Environmental Research and Technology (CE-CERT) has received a $100,000 grant from the Department of Energy to investigate ways of improving the performance of hydrogen engines in order to make them more competitive with fuel cell engines.
The work by the UCR research team, led by CE-CERT's principal engineer James Heffel, is part of a national initiative to develop hydrogen power. Much of that initiative centers on the development of pollution-free fuel cells. The UCR engineers, however, are looking at burning hydrogen, a more immediate and less costly solution.
"While most people may think burning hydrogen is pollution free, this is not necessarily the case," says Heffel. "It is true that burning hydrogen results in water, but because nitrogen in the air is used to burn the hydrogen, oxides of nitrogen, or NOx, are also formed."
NOx, considered to be a criteria pollutant, is formed in the combustion chamber of the engine, not because of the hydrogen per se, but because of oxygen and nitrogen in the air at high temperature during the combustion process.
"The formation of NOx also occurs when you burn gasoline," explains Heffel. "But in the case of hydrogen we have a wide flammability range and, therefore, the engine can be tuned to have a lower combustion temperature. This in turn results in lower NOx emissions."
In the past CE-CERT has used the "lean-burn" strategy to reduce the combustion temperature of the engine. This technique uses about twice the amount air normally needed to burn the fuel completely. A gasoline engine is unable to run properly at this extreme lean condition and therefore is unable to use this technique.
For the new project, CE-CERT will recirculate a large portion of the exhaust gas back into the combustion chamber instead of using excess air. "As strange as it may sound, this will actually reduce the combustion temperatures, too," says Heffel. "While the lean-burn strategy can reduce the NOx to near zero or a few parts per million, the new method should be able to reduce the NOx emissions to a few parts per billion, or what is normally found in the air we breathe." Indeed, the project will also focus on developing a new method to measure the emissions because they will be too low to be measured precisely by current instrumentation.
This project comes at a time when fuel cells are being touted as the energy source of the future. Recently, the Bush administration and domestic automakers launched a partnership to encourage the growth of hydrogen fuel cells to develop motor vehicle engine and power systems that they believe will eventually replace the internal combustion engine. Fuel cells electrochemically react hydrogen and air to produce water and electricity. Since this occurs at a much lower temperature, NOx formation does not occur.
Unfortunately, fuel cells are currently very costly. "Until the price of fuel cells come down, burning hydrogen in an engine may be the way to go" Heffel says. UCR mechanical engineering students, Kurt Anderson and Kevin Carpenter, will be assisting Heffel in the project, which is expected to be completed by the end of summer. Anderson also assisted Heffel in the development of a hydrogen powered 427 Cobra for legendary race-car driver and auto designer Carroll Shelby.