LCU pointed out that a blue flame, the hottest and best flame to have, indicates that there are no combustibles around the flame or in the air to burn off. An orange flame means the gas is not ...

What is the orange and blue flame at the Wellford Landfill? (It's not visible in bright daylight.) And why can't it be used to generate electricity? -- M.H., Lyman That flame, which can be seen ...