What,effects, if any, will LNG have on natural gas vehicles and what is SDG&E doing about it?
A. New gas supplies, such as LNG imports, will meet quality standards established by the California Public Utilities Commission but may differ from natural gas currently flowing in the SDG&E system. One measure of gas quality, used with vehicles, is the Methane Number (MN). It is similar to the octane ratings used with gasoline, but on a different scale. SDG&E expects new sources of natural gas entering the system to meet a minimum value of MN 80. SDG&E has reviewed manufacturer fuel specifications, developed engine performance studies, and funded engine performance research to assess compressed natural gas CNG engine performance under a variety of conditions. This work shows that at a minimum value of MN 80, all CNG vehicles will operate safely and reliably. The California Air Resources Board (CARB) has a separate statewide (CNG) fuel specification that sets prescriptive limits for each chemical constituent (i.e. ethane, propane, etc.). Although all CNG vehicles will operate safely an
