Methane yog ib hom ntawm cov pa roj, uas yog tsim los ntawm alkanes, suav nrog methane, ethane, tshuaj propane, thiab butane, nrog methane yog cov khoom tseem ceeb.
Qhov sib txawv, thee gas yog ib qho roj av uas muaj cov khoom sib xyaw ua ke, nrog carbon monoxide yog nws cov ntsiab lus tseem ceeb.