<div class="htmlview paragraph">Gaseous fuels (natural gas, synthetic natural gas and LP-Gases) used in transportation vehicles are assessed. The fuels’ physical properties require larger storage volumes than liquid fuels, posing unique environmental and safety problems. Gaseous fuels provide a significant portion of the U.S. energy supply but increased uses will probably increase imports; production of synthetic natural gas and the development of unconventional gas resources will not prevent imports due to increased demand. Gaseous fuels can allow increased efficiency of spark-ignition Otto Cycle internal combustion engines during warmup at the expense of reduced specific power output. Neat methanol allows increased fuel efficiency and specific power output and is easier to incorporate into a transportation vehicle. Gaseous fuels are best suited to stationary combustion systems served by pipelines. Liquid fuels are better suited to use in transportation; alternative liquid fuels should be developed with transportation use in mind.</div>