Liquefied natural gas has the potential to increase emissions of smog-forming nitrogen oxides by up to 20 percent if used to fuel Southern California?s growing fleet of natural gas?burning vehicles and stationary engines, say air-quality officials. Ironically, the South Coast Air Quality Management District has required cities and many industries around the Los Angeles area to convert thousands of trucks and buses from diesel to cleaner-burning compressed natural gas to clean up the dirty air. The move, however, could be partly reversed because LNG burns hotter than domestic gas and forms more NOx, a precursor to ozone. Increases in pollution also are expected from rising ship and truck traffic and boilers and diesel engines at the proposed plants that would pump LNG and regasify it before sending it into Southern California Gas Co. pipelines. To guard against any worsening of air quality, the regional smog-control district has recommended that a proposal by Sound Energy Solutions (SES) to build an LNG terminal at the Port of Long Beach include a variety of air pollution reduction measures. ?The environmental impact report should consider mitigation measures such as limits on the British thermal unit content of the produce gas achieved by removing ethane and propane prior to putting the gas in the pipeline,? wrote Steve Smith, environmental analysis program supervisor for the South Coast air district. He also suggested diluting the LNG with nitrogen or air to reduce its heating value. Tests show that LNG from 13 areas around the globe?including gas fields in Abu Dhabi, Algeria, Australia, Indonesia, Libya, Malaysia, Oman, and Qatar?does not meet the California Air Resources Board?s natural gas vehicle fuel specification, according to Beth Musich, LNG business manager for SoCal Gas. There also may be problems with burning LNG from some areas in other types of equipment, she said. The Federal Energy Regulatory Commission was expected this week to take up the issue of whether LNG could replace natural gas used in an array of equipment?from furnace burners to turbines. In addition, SoCal Gas, which has been instrumental in its support for natural gas in vehicles, expects to complete a study this spring that assesses the potential impact of regasified LNG on the region?s natural gas vehicle fleet. Smith also recommended that SES use only ships outfitted with selective catalytic reduction and oxidation catalysts to reduce emissions and that ships use only onshore energy while in port rather than running their engines to produce power. SES has proposed mitigating the potential air-quality impacts of its project by offering its LNG as fuel for heavy-duty vehicles and equipment that now burn diesel. ?It?s pro cleaning the air,? said Thomas Giles, managing director of the company. The Mitsubishi subsidiary plans to remove heavy gases on site to lower the Btu content of the gas it sends into the distribution pipeline and to run a fleet of trucks. LNG burns much more cleanly in these vehicles than diesel fuel and would offset any potential increase in emissions from natural gas vehicles, according to the air district. Proposals by other LNG developers, including Crystal Energy?s bid for an offshore terminal along the Ventura County coast, would not include as many mitigation measures to address air-quality concerns. SES?s pledge to make LNG available for heavy-duty vehicles pleases the California Natural Gas Vehicle Partnership. The group estimates that the region will need up to 2.6 million gallons a day of LNG to meet clean-air standards within 10 years, according to Tina Cherry, spokesperson for the South Coast air district, a member of the partnership. The group, which includes a host of companies and local, state, and federal agencies, is backing the SES project, she said.