Natural Gas as a Transportation Fuel

1. Sohail Ghanchi Energy Technology and Policy The University of Texas at Austin Natural Gas as a Transportation Fuel

2. Overview • Introduction • Benefits • Available Technologies • Current Uses • Implementation Challenges • Conclusion

3. What is Natural Gas? • A combustible gaseous mixture of hydrocarbons, primarily methane • Primarily extracted from oil and gas wells. Large deposits exist in 25 states • Accounts for 22% of US energy use and 2.2% of energy used for transportation

4. Benefits • Increased Energy Security • Natural gas is a domestically available fuel • Public Health and Environment Protection • Up t0 95% less particulate matter (compared to diesel) • 21-25% less greenhouse gas emissions*

5. CNG vs. LNG • CNG – 116,000 vehicles • Most common method of storing natural gas • Typical pressures range between 2,000 and 4000 psi (household NG pipe pressure is ~1-2 psi) • LNG – 3000 vehicles • Natural gas liquefies at -260F • LNG tanks are much more expensive than CNG tanks • Can store a lot more NG, but must be kept cool at all times Source: DOE

6. NG Engine Technology • Stoichiometric Natural Gas Engines • Operates with air/fuel mixture that contains only enough oxygen to burn all the fuel • Used in majority of light duty NG vehicles because they require low power • Lean Burn Technology • Far more air than needed to burn the fuel • Lowers peak combustion temp  lower NOx and PM emissions • Used in trucks and buses • Closed Loop Fuel Control

7. NG Fuel Quality • If standards are not met, air-fuel ratio in engine is disturbed, causing higher emissions and a reduction in efficiency • Water – formation of ice and particulates at low temperatures, can plug fuel lines • Sulfur – must be minimized to maximize the emission benefits

8. Light Duty NGV • Light Duty NGV use CNG • Currently limited to the Honda Civic • 190-225 miles on one tank • EPA certified conversions available from a variety of companies • Home refueling devices • Up to 16 hours to refill an empty tank at home

9. Retrofits • Gasoline to Natural Gas • No significant reduction in particulate matter emissions • NOx, VOC and CO decrease if proper fuel control and exhaust catalyst systems are installed • Diesel to Natural Gas • Up to 95% reduction in particulate matter emissions

10. Heavy Duty NGV • May use LNG or CNG • Larger engines typically use LNG • Natural Gas Transit buses – largest niche NG market • Annual consumption (2006): 109 million diesel gallon equivalent of natural gas • 15% of transit vehicles in 2006 powered by natural gas

11. Implementation Challenges • Vehicle Price – Natural gas vehicles cost more because of onboard fuel storage and engine modifications • Fuel Availability – Refueling is less readily available outside of California - most fleets build their own infrastructure

12. Natural Gas Fueling Stations More than 825 natural gas fueling stations in the United States: • 35 LNG • 790 CNG • 355 Public • 470 Private Source: DOE AFDC, Feb 2008

14. Tax Incentives • Vehicle Tax Credits (for new or retrofits) • Light Duty (up to 8,500 lb): up to $5,000 • Medium Duty (up to 14,000 lb): up to $10,000 • Medium-Heavy Duty (up to 26,000 lb): up to $25,000 • Heavy Duty (more than 26,000 lb): up to $40,000

15. Conclusions • Fuel quality must be controlled to allow for clean and durable vehicle operation • Increased production of NGVs will stimulate the construction of fueling stations • Heavy duty vehicles are best suited for NG usage