1. Sohail Ghanchi Energy Technology and Policy The University of Texas at Austin

2.  Introduction  Benefits  Available Technologies  Current Uses  Implementation Challenges  Conclusion

3.  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.  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 – 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.  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.  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 Proposed Minimum Fuel Quality Standards Methane95% minimum Propane2-5% maximum Butane1-5% maximum Sulfur8-30 ppm maximum

8.  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.  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.  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.  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. 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.  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.  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