Natural Gas

CNG vehicles in North America use this diamond symbol.

Example of CNG-powered bus

eTec/Roush H2 Silverado

Hydrogen/Natural Gas Blends

The target of Argonne's investigations is to identify the difference in combustion behavior, efficiency, engine performance and emissions of compressed natural gas (CNG) blends as compared to pure hydrogen operation.

Previous Research

Previous work has addressed pure CNG as well as pure hydrogen operation. Testing of CNG-hydrogen blends has been limited to CNG-rich blends and blends of 50%-50% CNG-H₂. In order to investigate actual vehicle behavior using this fuel, there is a need to test hydrogen-rich blends in a research engine.

Studies using hydrogen/methane blends have shown that

• Blending hydrogen with methane reduces the demand for hydrogen
• Hydrogen offers unique combustion properties even in blended operation
• Blending has improved on-board storage density

In order to investigate actual vehicle behavior using this fuel, there was a need to test hydrogen-rich blends in a research engine. A single-cylinder engine was used, as well as an eTec/Roush H2 Silverado vehicle. Experiments concluded that

• Blending hydrogen with methane did effectively reduce the hydrogen demand
• Slower combustion speed of blends compared to pure hydrogen can be partially compensated for with spark timing adjustment
• Blending significantly increases the vehicle range
• Reduction of NOx emissions with increased amount of methane in the blend
• Tier II Bin 5 emissions regulations can be met without aftertreatment

References

• The effects of blending hydrogen with methane on engine operation, efficiency, and emissions (pdf, 158 kB)
• Results of Research Engine and Vehicle Drive Cycle Testing during Blended Hydrogen/Methane Operation (pdf, 2.45 MB)

Funding

This work was funded by the Department of Energy's Office of Energy Efficiency and Renewable Energy.

More

• Hydrogen research

February 2010