Answer: methane

AnswerCrossword Clue
METHANEIt's a gas!
methanecolorless, odorless, flammable gas
METHANEDairy farm product
METHANEFiredamp, for the most part
METHANEMarsh emanation
METHANEFuel gas
METHANEFlammable gas
METHANEType of gas
METHANECH4 (natural gas)
METHANEGreenhouse gas produced by cows
METHANECoal miner's concern
METHANEDangerous buildup in a mine
METHANENatural gas constituent
METHANEMarsh gas constituent
METHANEMarsh gas, essentially
METHANEMarsh gas
METHANEDangerous mine gas.
METHANEFiredamp.
METHANEMarsh gas.
METHANEHydrocarbon used as fuel.
METHANEA greenhouse gas
METHANEA natural gas
METHANECoal mine product
METHANEPolluting gas
METHANEIt's a gas
METHANEMarsh gas, mostly
METHANESwamp gas, mostly
METHANESwamp gas, essentially
METHANEMarsh hydrocarbon
METHANECH4